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Encyclopedia > Infectious disease
This false-colored electron micrograph shows a malaria sporozoite migrating through the midgut epithelia.

An infectious disease is a clinically evident disease resulting from the presence of pathogenic microbial agents, including viruses, bacteria, fungi, protozoa, multicellular parasites, and aberrant proteins known as prions. These pathogens are able to cause disease in animals and/or plants. Image File history File links Malaria. ... Image File history File links Malaria. ... An electron micrograph is a micrograph made with an electron microscope. ... Malaria is a vector-borne infectious disease caused by protozoan parasites. ... In the life-cycle of apicomplexan protozoa, sporozoites are cells that infect new hosts. ... In zootomy, epithelium is a tissue composed of a layer of cells. ... This article is about the medical term. ... A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... This article is about biological infectious particles. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... Wikisource has an original article from the 1911 Encyclopædia Britannica about: Protozoa Protozoa (in Greek proto = first and zoa = animals) are single-celled eukaryotes (organisms whose cells have nuclei) that commonly show characteristics usually associated with animals, most notably mobility and heterotrophy. ... A parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism and which causes harm to the host without immediately killing it. ... A prion (IPA: [1] ) — short for proteinaceous infectious particle (-on by analogy to virion) — is a type of infectious agent composed only of protein. ... A pathogen or infectious agent is a biological agent that causes disease or illness to its host. ...


Infectious pathologies are usually qualified as contagious diseases (also called communicable diseases) due to their potentiality of transmission from one person or species to another.[1] Transmission of an infectious disease may occur through one or more of diverse pathways including physical contact with infected individuals. These infecting agents may also be transmitted through liquids, food, body fluids, contaminated objects, airborne inhalation, or through vector-borne spread.[2] In epidemiology, a vector is an organism that does not cause disease itself but which spreads infection by conveying pathogens from one host to another. ...


The term infectivity describes the ability of an organism to enter, survive and multiply in the host, while the infectiousness of a disease indicates the comparative ease with which the disease is transmitted to other hosts.[3] An infection however, is not synonymous with an infectious disease, as an infection may not cause important clinical symptoms or impair host function.[2] In Epidemiology, Infectivity refers to the ability of a ability of a pathogen to establish an infection. ... An infection is the detrimental colonization of a host organism by a foreign species. ... Synonyms (in ancient Greek syn συν = plus and onoma όνομα = name) are different words with similar or identical meanings. ...

Contents

Classification

Among the almost infinite varieties of microorganisms, relatively few cause disease in otherwise healthy individuals.[4] Infectious disease results from the interplay between those few pathogens and the defenses of the hosts they infect. The appearance and severity of disease resulting from any pathogen depends upon the ability of that pathogen to damage the host as well as the ability of the host to resist the pathogen. Infectious microorganisms, or microbes, are therefore classified as either primary pathogens or as opportunistic pathogens according to the status of host defenses.


Primary pathogens cause disease as a result of their presence or activity within the normal, healthy host, and their intrinsic virulence (the severity of the disease they cause) is, in part, a necessary consequence of their need to reproduce and spread. Many of the most common primary pathogens of humans only infect humans, however many serious diseases are caused by organisms acquired from the environment or which infect non-human hosts. Virulence refers to the degree of pathogenicity of a microbe, or in other words the relative ability of a microbe to cause disease. ...


Organisms which cause an infectious disease in a host with depressed resistance are classified as opportunistic pathogens. Opportunistic disease may be caused by microbes that are ordinarily in contact with the host, such as bacteria or fungi in the gastrointestinal or the upper respiratory tract, and they may also result from (otherwise innocuous) microbes acquired from other hosts (as in Clostridium difficile enterocolitis) or from the environment as a result of traumatic introduction (as in surgical wound infections or compound fractures). An opportunistic disease requires impairment of host defenses, which may occur as a result of genetic defects (such as Chronic granulomatous disease), exposure to antimicrobial drugs or immunosuppressive chemicals (as might occur following poisoning or cancer chemotherapy), exposure to ionizing radiation, or as a result of an infectious disease with immunosuppressive activity (such as with measles, malaria or HIV disease). Primary pathogens may also cause more severe disease in a host with depressed resistance than would normally occur in an immunosufficient host. For the Physics term GUT, please refer to Grand unification theory The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and... The Upper respiratory tract refers to the the following parts of the respiratory system: nose and nasal passages paranasal sinuses throat or pharynx Upper respiratory tract infections are among the most common infections in the world. ... Binomial name Hall & OToole, 1935 Clostridium difficile or CDF/cdf (commonly mistaken  , alternatively and correctly pronounced ) (also referred to as C. diff or C-diff) is a species of bacteria of the genus Clostridium which are gram-positive, anaerobic, spore-forming rods (bacillus). ... Enterocolitis (or coloenteritis) is an inflammation of both the small and large intestine. ... In medicine, a trauma patient has suffered serious and life-threatening physical injury resulting in secondary complications such as shock, respiratory failure and death. ... Surgery Surgery is the medical specialty that treats diseases or injuries by operative manual and instrumental treatment. ... A bone fracture is a medical condition in which a bone becomes cracked, splintered, or bisected as a result of physical trauma. ... A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. ... Chronic granulomatous disease (CGD) is a diverse group of hereditary diseases in which certain cells of the immune system have difficulty forming the reactive oxygen compounds (most importantly, the superoxide radical) used to kill certain ingested pathogens. ... An antimicrobial is a substance that kills or slows the growth of microbes like bacteria (antibacterial activity), fungi (antifungal activity), viruses (antiviral activity), or parasites (antiparasitic activity). ... Immunosuppression is the medical suppression of the immune system. ... The skull and crossbones symbol (Jolly Roger) traditionally used to label a poisonous substance. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ... Chemotherapy is the use of chemical substances to treat disease. ... Radiation hazard symbol. ... Malaria is a vector-borne infectious disease caused by protozoan parasites. ... Human immunodeficiency virus (HIV) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS), a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections. ...


One way of proving that a given disease is "infectious", is to satisfy Koch's postulates (first proposed by Robert Koch), which demands that the infectious agent be identified only in patients and not in healthy controls, and that patients who contract the agent also develop the disease. These postulates were first used in the discovery that Mycobacteria species cause tuberculosis. Koch's postulates cannot be met ethically for many human diseases because they require experimental infection of a healthy individual with a pathogen produced as a pure culture. Often, even diseases that are quite clearly infectious do not meet the infectious criteria. For example, Treponema pallidum, the causative spirochete of syphilis, cannot be cultured in vitro - however the organism can be cultured in rabbit testes. It is less clear that a pure culture comes from an animal source serving as host than it is when derived from microbes derived from plate culture. Epidemiology is another important tool used to study disease in a population. For infectious diseases it helps to determine if a disease outbreak is sporadic (occasional occurrence), endemic (regular cases often occurring in a region), epidemic (an unusually high number of cases in a region), or pandemic (a global epidemic). Kochs postulates (or Henle-Koch postulates) are four criteria designed to establish a causal relationship between a causative microbe and a disease. ... For the American lobbyist, see Bobby Koch. ... In medicine, infectious disease or communicable disease is disease caused by a biological agent (e. ... Species see text Mycobacterium is the a genus of actinobacteria, given its own family, the Mycobacteriaceae. ... Tuberculosis (abbreviated as TB for tubercle bacillus or TuBerculosis) is a common and deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. ... Binomial name Treponema pallidum Schaudinn & Hoffmann, 1905 Treponema pallidum is a gram-negative spirochaete bacterium and is considered to be metabolically crippled. ... Families Brachyspiraceae Leptospiraceae Spirochaetaceae The spirochaetes are a phylum of distinctive bacteria, which have long, helically coiled cells. ... Syphilis is a sexually transmitted disease caused by Treponema pallidum. ... A microbiological culture is a way to determine the cause of infectious disease by letting the agent multiply (reproduce) in predetermined media. ... Human male anatomy The testicles, known medically as testes (singular testis), are the male generative glands in animals. ... Epidemiology is the study of factors affecting the health and illness of populations, and serves as the foundation and logic of interventions made in the interest of public health and preventive medicine. ... Virus outbreaks occur when a virus bypasses infection control measures and a relatively high number of infections are observed where no cases or sporadic cases occurred in the past. ... In epidemiology, an infection is said to be endemic in a population when that infection is maintained in the population without the need for external inputs. ... In epidemiology, an epidemic (from [[Latin language] epi- upon + demos people) is a disease that appears as new cases in a given human population, during a given period, at a rate that substantially exceeds what is expected, based on recent experience (the number of new cases in the population during... This article is about large epidemics. ...


Transmission

An infectious disease is transmitted from some source. Defining the means of transmission plays an important part in understanding the biology of an infectious agent, and in addressing the disease it causes. Transmission may occur through several different mechanisms. Respiratory diseases and meningitis are commonly acquired by contact with aerosolized droplets, spread by sneezing, coughing, talking or even singing. Gastrointestinal diseases are often acquired by ingesting contaminated food and water. Sexually transmitted diseases are acquired through contact with bodily fluids, generally as a result of sexual activity. Some infectious agents may be spread as a result of contact with a contaminated, inanimate object (known as a fomite), such as a coin passed from one person to another, while other diseases penetrate the skin directly.[5] In animal physiology, respiration is the transport of oxygen from the ambient air to the tissue cells and the transport of carbon dioxide in the opposite direction. ... Meningitis is the inflammation of the protective membranes covering the central nervous system, known collectively as the meninges. ... For the Physics term GUT, please refer to Grand unification theory The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and... A sexually transmitted infection (STI) is an illness caused by an infectious pathogen that has a significant probability of transmission between humans by means of sexual contact, including vaginal intercourse, oral sex, and anal sex. ... A fomite is any inanimate object or substance supposed to be capable of absorbing, retaining, and transporting contagious or infectious organisms (from germs to parasites) from one individual to another. ... Beyond overall skin structure, refer below to: See-also. ...


Transmission of infectious diseases may also involve a "vector". Vectors may be mechanical or biological. A mechanical vector picks up an infectious agent on the outside of its body and transmits it in a passive manner. An example of a mechanical vector is a housefly, which lands on cow dung, contaminating its appendages with bacteria from the feces, and then lands on food prior to consumption. The pathogen never enters the body of the fly. In epidemiology, a vector is an organism that does not cause disease itself but which spreads infection by conveying pathogens from one host to another. ... Binomial name Linnaeus, 1758 The housefly (also house fly or house-fly), Musca domestica, is the most common fly occurring in homes, the most familiar of all flies and indeed one of the most widely distributed animals; it is a pest that can carry and transmit serious diseases. ...

Culex mosquitos (Culex quinquefasciatus shown) are biological vectors that transmit West Nile Virus.

In contrast, biological vectors harbor pathogens within their bodies and deliver pathogens to new hosts in an active manner, usually a bite. Biological vectors are often responsible for serious blood-borne diseases, such as malaria, viral encephalitis, Chagas disease and African sleeping sickness. Biological vectors are usually, though not exclusively, arthropods, such as mosquitoes, ticks, fleas and lice. Vectors are often required in the life cycle of a pathogen. A common strategy, used to control vector borne infectious diseases, is to interrupt the life cycle of a pathogen, by killing the vector. Image File history File links CulexNil. ... Image File history File links CulexNil. ... West Nile virus (WNV) is a virus of the family Flaviviridae; part of the Japanese encephalitis (JE) antigenic complex of viruses, it is found in both tropical and temperate regions. ... A blood-borne disease is one that can be spread by contamination by blood. ... Malaria is a vector-borne infectious disease caused by protozoan parasites. ... Encephalitis is an acute inflammation of the brain, commonly caused by a viral infection. ... Sleeping sickness or African trypanosomiasis is a parasitic disease in humans. ... Subphyla and Classes Subphylum Trilobitomorpha Trilobita - Trilobites (extinct) Subphylum Chelicerata Arachnida - Spiders, Scorpions, etc. ... This article is about the insect; for the WWII aircraft see De Havilland Mosquito. ... Families Ixodidae - Hard ticks Argasidae - Soft ticks Nuttalliellidae - ????? ticks Wikispecies has information related to: Ixodoidea Tick is the common name for the small arachnids that, along with other mites, constitute the order Acarina. ... Adam had em. ... Suborders Anoplura (sucking lice) Rhyncophthirina Ischnocera (avian lice) Amblycera (chewing lice) Lice (singular: louse) (order Phthiraptera) are an order of over 3000 species of wingless parasitic insects. ...


The relationship between virulence and transmission is complex, and has important consequences for the long term evolution of a pathogen. Since it takes time for a microbe and a new host species to co-evolve, an emerging pathogen may hit its earliest victims especially hard. It is usually in the first wave of a new disease that death rates are highest. If a disease is rapidly fatal, the host may die before the microbe can get passed along to another host. However, this cost may be overwhelmed by the short term benefit of higher infectiousness if transmission is linked to virulence, as it is for instance in the case of cholera (the explosive diarrhea aids the bacterium in finding new hosts) or many respiratory infections (sneezing and coughing create infectious aerosols). Aerosol, is a term derived from the fact that matter floating in air is a suspension (a mixture in which solid or liquid or combined solid-liquid particles are suspended in a fluid). ...


Diagnosis and therapy

Diagnosis of infectious disease sometimes involves identifying an infectious agent either directly or indirectly. In practice most minor infectious diseases such as warts, cutaneous abscesses, respiratory system infections and diarrheal diseases are diagnosed by their clinical presentation. Conclusions about the cause of the disease are based upon the likelihood that a patient came in contact with a particular agent, the presence of a microbe in a community, and other epidemiological considerations. Given sufficient effort, all known infectious agents can be specifically identified. The benefits of identification, however, are often greatly outweighed by the cost, as often there is no specific treatment, the cause is obvious, or the outcome of an infection is benign. Wart is also the name of a Nintendo character, see Wart (Nintendo character). ... This article is about skin in the biological sense. ... An abscess is a collection of pus collected in a cavity formed by the tissue on the basis of an infectious process (usually caused by bacteria or parasites) or other foreign materials (e. ... The Respiratory System Among four-legged animals, the respiratory system generally includes tubes, such as the bronchi, used to carry air to the lungs, where gas exchange takes place. ... Types 5-7 on the Bristol Stool Chart are often associated with diarrhea Diarrhea (in American English) or diarrhoea (in British English) is a generally unpleasant condition in which the sufferer has frequent watery, loose bowel movements (from the ancient Greek word διαρροή = leakage; literally meaning to run through). Acute infectious... Look up Benign in Wiktionary, the free dictionary. ...


Specific identification of an infectious agent is usually only determined when such identification can aid in the treatment or prevention of the disease, or to advance knowledge of the course of an illness prior to the development of effective therapeutic or preventative measures. For example, in the early 1980s, prior to the appearance AZT for the treatment of AIDS, the course of the disease was closely followed by monitoring the composition of patient blood samples, even though the outcome would not offer the patient any further treatment options. In part, these studies on the appearance of HIV in specific communities permitted the advancement of hypotheses as to the route of transmission of the virus. By understanding how the disease was transmitted, resources could be targeted to the communities at greatest risk in campaigns aimed at reducing the number of new infections. The specific serological diagnostic identification, and later genotypic or molecular identification, of HIV also enabled the development of hypotheses as to the temporal and geographical origins of the virus, as well as a myriad of other hypothesis. The development of molecular diagnostic tools have enabled physicians and researchers to monitor the efficacy of treatment with anti-retroviral drugs. Molecular diagnostics are now commonly used to identify HIV in healthy people long before the onset of illness and have been used to demonstrate the existence of people who are genetically resistant to HIV infection. Thus, while there still is no cure for AIDS, there is great therapeutic and predictive benefit to identifying the virus and monitoring the virus levels within the blood of infected indiviuals, both for the patient and for the community at large. Zidovudine (INN) or azidothymidine (abbreviated to AZT) is an anti-retroviral drug, the first antiviral treatment to be approved for use against HIV. It is also sold under the names Retrovir and Retrovis, and as an ingredient in Combivir and Trizivir. ... For other uses, see AIDS (disambiguation). ... Species Human immunodeficiency virus 1 Human immunodeficiency virus 2 Human immunodeficiency virus (HIV) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS, a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections). ... A hypothesis (= assumption in ancient Greek) is a proposed explanation for a phenomenon. ... Serology is a medical blood test to detect the presence of antibodies against a microorganism. ... The genotype is the specific genetic makeup (the specific genome) of an individual, usually in the form of DNA. It codes for the phenotype of that individual. ... For alternate uses of time, see Time (disambiguation) or see TIME (magazine). ... Physical map of the Earth (Medium) (Large 2 MB) Geography is the scientific study of the locational and spatial variation in both physical and human phenomena on Earth. ... Antiretroviral drugs are medications for the treatment of infection by the retrovirus HIV. Different antiretroviral drugs act at various stages of the HIV life cycle. ...


Methods of diagnosis

Diagnosis of infectious disease is nearly always initiated by medical history and physical examination. More detailed identification techniques involve the culture of infectious agents isolated from a patient. Culture allows identification of infectious organisms by examining their microscopic features, by detecting the presence of substances produced by pathogens, and by directly identifying an organism by its genotype. Other techniques (such as X-rays, CAT scans, PET scans or NMR) are used to produce images of internal abnormalities resulting from the growth of an infectious agent. The images are useful in detection of, for example, a bone abscess or a spongiform encephalopathy produced by a prion. In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... CAT apparatus in a hospital Computed axial tomography (CAT), computer-assisted tomography, computed tomography, CT, or body section roentgenography is the process of using digital processing to generate a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images taken around... Positron emission tomography (PET) is a nuclear medicine medical imaging technique which produces a three dimensional image or map of functional processes in the body. ... NMR may refer to: Nuclear magnetic resonance, a phenomenon involving the interaction of atomic nuclei and external magnetic fields Nielsen Media Research, a U.S. company which measures TV, radio and newspaper audiences This is a disambiguation page — a navigational aid which lists other pages that might otherwise share... For the death metal band, see Abscess (band). ... Transmissible spongiform encephalopathies (TSEs, also known as prion diseases) are a group of progressive conditions that affect the brain and nervous system of humans and animals and are transmitted by prions. ... A prion (IPA: [1] ) — short for proteinaceous infectious particle (-on by analogy to virion) — is a type of infectious agent composed only of protein. ...


Microbial culture

Four nutrient agar plates growing colonies of common Gram negative bacteria.

Microbiological culture is a principal tool used to diagnose infectious disease. In a microbial culture, a growth medium is provided for a specific agent. A sample taken from potentially diseased tissue or fluid is then tested for the presence of an infectious agent able to grow within that medium. Most pathogenic bacteria are easily grown on nutrient agar, a form of solid medium that supplies carbohydrates and proteins necessary for growth of a bacterium, along with copious amounts of water. A single bacterium will grow into a visible mound on the surface of the plate called a colony, which may be separated from other colonies or melded together into a "lawn". The size, color, shape and form of a colony is characteristic of the bacterial species, its specific genetic makeup (its strain), and the environment which supports its growth. Other ingredients are often added to the plate to aid in identification. Plates may contain substances that permit the growth of some bacteria and not others, or that change color in response to certain bacteria and not others. Bacteriological plates such as these are commonly used in the clinical identification of infectious bacteria. Microbial culture may also be used in the identification of viruses: the medium in this case being cells grown in culture that the virus can infect, and then alter or kill. In the case of viral identification, a region of dead cells results from viral growth, and is called a "plaque". Eukaryotic parasites may also be grown in culture as a means of identifying a particular agent. Image File history File links Size of this preview: 549 × 599 pixel Image in higher resolution (772 × 843 pixel, file size: 101 KB, MIME type: image/jpeg) Four nutrient agar plates growing colonies of common Gram negative bacteria. ... Image File history File links Size of this preview: 549 × 599 pixel Image in higher resolution (772 × 843 pixel, file size: 101 KB, MIME type: image/jpeg) Four nutrient agar plates growing colonies of common Gram negative bacteria. ... A microbiological culture is a way to determine the cause of infectious disease by letting the agent multiply (reproduce) in predetermined media. ... An Agar Plate -- an example of a bacterial growth medium. ... This does not adequately cite its references or sources. ... This is a biological article: For a territory administered by another territory see: Colony For a group attempting to affiliate with a Fraternity or Sorority see: Colony (fraternity) In biology, a colony (from Latin colonia) refers to several individual organisms of the same species living closely together, usually for mutual... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... This article is about biological infectious particles. ... Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... A parasite is an organism that lives in or on the living tissue of a host organism at the expense of it. ...


In the absence of suitable plate culture techniques, some microbes require culture within live animals. Bacteria such as Mycobacterium leprae and T. pallidum can be grown in animals, although serological and microscopic techniques make the use of live animals unnecessary. Viruses are also usually identified using alternatives to growth in culture or animals. Some viruses may be grown in embryonated eggs. Another useful identification method is Xenodiagnosis, or the use of a vector to support the growth of an infectious agent. Chaga's disease is the most significant example, because it is difficult to directly demonstrate the presence of the causative agent, Trypanosoma cruzi in a patient, which therefore makes it difficult to definitively make a diagnosis. In this case, xenodiagnosis involves the use of the vector of the Chaga's agent T. cruzi, an uninfected triatomine bug (subfamily Triatominae), which takes a blood meal from a person suspected of having been infected. The bug is later inspected for growth of T. cruzi within its gut. For other uses, see Embryo (disambiguation). ... Trypanosoma cruzi is a species of parasitic protozoan trypanosomes. ... In epidemiology, a vector is an organism that does not cause disease itself but which spreads infection by conveying pathogens from one host to another. ... The members of Triatominae, a subfamily of Reduviidae, are also known as conenose bugs, kissing bugs or triatomines. ...


Microscopy

Another principle tool in the diagnosis of infectious disease is microscopy. Virtually all of the culture techniques discussed above rely, at some point, on microscopic examination for definitive identification of the infectious agent. Microscopy may be carried out with simple instruments, such as the compound light microscope, or with instruments as complex as an electron microscope. Samples obtained from patients may be viewed directly under the light microscope, and can often rapidly lead to identification. Microscopy is often also used in conjunction with biochemical staining techniques, and can be made exquisitely specific when used in combination with antibody based techniques. For example, the use of antibodies made artificially fluorescent (fluorescently labeled antibodies) can be directed to bind to and identify a specific antigens present on a pathogen. A fluorescence microscope is then used to detect fluorescently labeled antibodies bound to internalized antigens within clinical samples or cultured cells. This technique is especially useful in the diagnosis of viral diseases, where the light microscope is incapable of identifying a virus directly. This article or section is not written in the formal tone expected of an encyclopedia article. ... This article or section is not written in the formal tone expected of an encyclopedia article. ... 1852 microscope Compound microscope made by John Cuff in 1750 A microscope (Greek: micron = small and scopos = aim) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. ... An electron microscope is a type of microscope that uses electrons to illuminate and create an image of a specimen. ... Biochemistry is the chemistry of life. ... ... Each antibody binds to a specific antigen; an interaction similar to a lock and key. ... Wikipedia does not yet have an article with this exact name. ... Fluorescence induced by exposure to ultraviolet light in vials containing various sized cadmium selenide (CdSe) quantum dots. ... An antigen is any molecule that is recognized by antibodies. ... A Fluorescence Microscope is a light microscope used to study properties of organic or inorganic substances using the phenomena of fluorescence and phosphorescence instead of, or in addition to, reflection and absorption. ...


Other microscopic procedures may also aid in identifying infectious agents. Almost all cells readily stain with a number of basic dyes due to the electrostatic attraction between negatively charged cellular molecules and the positive charge on the dye. A cell is normally transparent under a microscope, and using a stain increases the contrast of a cell with its background. Staining a cell with a dye such as Giemsa stain or crystal violet allows a microscopist to describe its size, shape, internal and external components and its associations with other cells. The response of bacteria to different staining procedures is used in the taxonomic classification of microbes as well. Two methods, the Gram stain and the acid-fast stain, are the standard approaches used to classify bacteria and to diagnosis of disease. The Gram stain identifies the bacterial groups Firmicutes and Actinobacteria, both of which contain many significant human pathogens. The acid-fast staining procedure identifies the Actinobacterial genera Mycobacterium and Nocardia. Look up dye in Wiktionary, the free dictionary. ... Electrostatics is the branch of physics that deals with the force exerted by a static (i. ... A complex of stains specific for the phosphate groups of DNA. Used in Giemsa banding (or G-banding) to stain chromosomes and often used to create a karyotype. ... Structure of Methyl Violet 2B Methyl violet is the name given to a group of similar chemicals used as pH indicators and dyes. ... It has been suggested that this article or section be merged into Concept mining. ... Gram staining is a method for staining samples of bacteria that differentiates between the two main types of bacterial cell wall. ... A bacillus is a rod-shaped bacterium: an acid-fast bacillus (or AFB) is a rod-shaped bacterium which, when stained with certain compounds, retains that stain despite treatment with an acidic solution. ... Classes Bacilli Clostridia Mollicutes The Firmicutes are a division of bacteria, most of which have Gram-positive cell wall structure. ... Subclasses Acidimicrobidae Actinobacteridae Coriobacteridae Rubrobacteridae Sphaerobacteridae The Actinobacteria or Actinomycetes are a group of Gram-positive bacteria. ... Species See text. ... Nocardia is a genus of Gram-positive, catalase-positive, rod-shaped bacteria; some species are pathogenic (nocardiosis). ...


Biochemical tests

Biochemical tests used in the identification of infectious agents include the detection of metabolic or enzymatic products characteristic of a particular infectious agent. Since bacteria ferment carbohydrates in patterns characteristic of their genus and species, the detection of fermentation products is commonly used in bacterial identification. Acids, alcohols and gases are usually detected in these tests when bacteria are grown in selective liquid or solid media. Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος(metavallo), the Greek word for change), in the most general sense, is the ingestion and breakdown of complex compounds, coupled... Neuraminidase ribbon diagram An enzyme (in Greek en = in and zyme = blend) is a protein, or protein complex, that catalyzes a chemical reaction and also controls the 3D orientation of the catalyzed substrates. ... Lactose is a disaccharide found in milk. ... For other uses, see Genus (disambiguation). ... For other uses, see Species (disambiguation). ... It has been suggested that this article or section be merged with Fermentation (food). ... For alternative meanings see acid (disambiguation). ... In general usage, alcohol (from Arabic al-khwl الكحول, or al-ghawl الغول) refers almost always to ethanol, also known as grain alcohol, and often to any beverage that contains ethanol (see alcoholic beverage). ... -1... An Agar Plate -- an example of a bacterial growth medium. ...


The isolation of enzymes from infected tissue can also provide the basis of a biochemical diagnosis of an infectious disease. For example, humans can make neither RNA replicases nor reverse transcriptase, and the presence of these enzymes are characteristic of specific types of viral infections. The ability of the viral protein hemagglutinin to bind red blood cells together into a detectable matrix may also be characterized as a biochemical test for viral infection, although strictly speaking hemagglutinin is not an enzyme and has no metabolic function. Neuraminidase ribbon diagram An enzyme (in Greek en = in and zyme = blend) is a protein, or protein complex, that catalyzes a chemical reaction and also controls the 3D orientation of the catalyzed substrates. ... RNA replicase is a polymerase enzyme that catalyzes the self-replication of single-stranded RNA. it is RNA dependent RNA plwhich is not haVING PRROFREEDING ACTIVITY. THIS IS ANOTHER EXTENSION IN THE CENTRADOGMA. IT IS MADE UP OF THREE SUBUNIT. Categories: | ... In biochemistry, a reverse transcriptase, also known as RNA-dependent DNA polymerase, is a DNA polymerase enzyme that transcribes single-stranded RNA into double-stranded DNA. Normal transcription involves the synthesis of RNA from DNA, hence reverse transcription is the reverse of this. ... Hemagglutinin, as depicted in a simplified molecular model. ... Human red blood cells Red blood cells are the most common type of blood cell and are the vertebrate bodys principal means of delivering oxygen to body tissues via the blood. ...


Serological methods are highly sensitive, specific and often extremely rapid tests used to identify microorganisms. These tests are based upon the ability of an antibody to bind specifically to an antigen. The antigen, usually a protein or carbohydrate made by an infectious agent, is bound by the antibody. This binding then sets off a chain of events that can be visibly obvious in various ways, dependent upon the test. For example, "Strep throat" is often diagnosed within minutes, and is based on the appearance of antigens made by the causative agent, S. pyogenes, that is retrieved from a patients throat with a cotton swab. Serological tests, if available, are usually the preferred route of identification, however the tests are costly to develop and the reagents used in the test often require refrigeration. Some serological methods are extremely costly, although when commonly used, such as with the "strep test", they can be inexpensive. Serology is a medical blood test to detect the presence of antibodies against a microorganism. ... Strep throat (or Streptococcal pharyngitis, or Streptococcal Sore Throat) is a form of Group A streptococcal infection that affects the pharynx. ... Binomial name Streptococcus pyogenes Rosenbach 1884 Streptococcus pyogenes is a Gram-positive cocci that grows in long chains depending on the culture method. ... Refrigeration is the process of removing heat from an enclosed space, or from a substance, and rejecting it elsewhere for the primary purpose of lowering the temperature of the enclosed space or substance and then maintaining that lower temperature. ...


Molecular diagnostics

Technologies based upon the polymerase chain reaction (PCR) will become nearly ubiquitous gold standards of diagnostics of the near future, for several reasons. First, the catalog of infectious agents has grown to the point that virtually all of the significant infectious agents of the human population have been identified. Second, an infectious agent must grow within the human body to cause disease; essentially it must amplify its own nucleic acids in order to cause a disease. This amplification nucleic acid in infected tissue offers an opportunity to detect the infectious agent by using PCR. Third, the essential tools for generating PCR (primers) are defined by the genomes of the infectious agents, and with time those genomes will be known, if they are not already. “PCR” redirects here. ... Wikipedia does not yet have an article with this exact name. ... Primer can refer to more than one thing: In molecular biology, a primer is nucleic acid strand (or related molecule) that serves as a starting point for DNA replication. ... Genome is also a popular science book by Matt Ridley. ...


Thus, the technological ability to detect any infectious agent rapidly and specifically are currently available. The only remaining blockades to the use of PCR as a standard tool of diagnosis are in its cost and application, neither of which is insurmountable. The diagnosis of a few diseases will not benefit from the development of PCR methods, such as some of the clostridial diseases (tetanus and botulism). These diseases are fundamentally biological poisonings by relatively small numbers of infectious bacteria that produce extremely potent neurotoxins. A significant proliferation of the infectious agent does not occur, this limits the ability of PCR to detect the presence of any bacteria. Orders The Clostridia are a class of Firmicutes, including Clostridium and other similar genera. ... Tetanus is a medical condition that is characterized by a prolonged contraction of skeletal muscle fibers. ... Botulism (Latin, botulus, sausage) is a rare, but serious paralytic illness caused by a nerve toxin, botulin, that is produced by the bacterium Clostridium botulinum. ... A neurotoxin is a toxin that acts specifically on nerve cells – neurons – usually by interacting with membrane proteins such as ion channels. ...


Clearance and immunity

Mary Mallon (a.k.a Typhoid Mary) was an asymptomatic carrier of typhoid fever. Over the course of her career as a cook, she infected 53 people, three of whom died.

Infection with most pathogens does not result in death of the host and the offending organism is ultimately cleared after the symptoms of the disease have waned.[4] This process requires immune mechanisms to kill or inactivate the inoculum of the pathogen. Specific acquired immunity against infectious diseases may be mediated by antibodies and/or T lymphocytes. Immunity mediated by these two factors may be manifested by: Image File history File links Mallon-Mary_01. ... Image File history File links Mallon-Mary_01. ... Typhoid Mary in a 1909 newspaper illustration Mary Mallon (September 23, 1869 – November 11, 1938), also known as Typhoid Mary, was the first person in the United States to be identified as a healthy carrier of typhoid fever. ... For a similar disease with a similar name, see typhus. ... A scanning electron microscope image of a single neutrophil (yellow), engulfing anthrax bacteria (orange). ... Inoculation, originally Variolation, is a method of purposefully infecting a person with smallpox (Variola) in a controlled manner so as to minimise the severity of the infection and also to induce immunity against further infection. ... Immunity is a medical term that describes a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. ... Wikipedia does not yet have an article with this exact name. ... T cells are a subset of lymphocytes that play a large role in the immune response. ...

  • a direct effect upon a pathogen, such as antibody-initiated complement-dependent bacteriolysis, opsonoization, phagocytosis and killing, as occurs for some bacteria,
  • neutralization of viruses so that these organisms cannot enter cells,
  • or by T lymphocytes which will kill a cell parasitized by a microorganism.

The immune response to a microorganism often causes symptoms such as a high fever and inflammation, and has the potential to be more devastating than direct damage caused by a microbe. A complement protein attacking an invader. ... An opsonin is any molecule that acts as a binding enhancer for the process of phagocytosis, for example, by coating the negatively-charged molecules on the membrane. ... Steps of a macrophage ingesting a pathogen: a. ... This article needs additional references or sources for verification. ... An abscess on the skin, showing the redness and swelling characteristic of inflammation. ...


Resistance to infection (immunity) may be acquired following a disease, by asymptomatic carriage of the pathogen, by harboring an organism with a similar structure (crossreacting), or by vaccination. Knowledge of the protective antigens and specific acquired host immune factors is more complete for primary pathogens than for opportunistic pathogens. Immunity is a medical term that describes a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. ... An asymptomatic carrier (or just carrier), is a person who is infected with an infectious disease or carries the abnormal gene of a recessive genetic disorder, but displays no symptoms. ... A vial of the vaccine against influenza. ...


Immune resistance to an infectious disease requires a critical level of either antigen-specific antibodies and/or T cells when the host encounters the pathogen. Some individuals develop natural serum antibodies to the surface polysaccharides of some agents although they have had little or no contact with the agent, these natural antibodies confer specific protection to adults and are passively transmitted to newborns. Look up Serum in Wiktionary, the free dictionary. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... Passive immunity occurs when high levels of human (or horse) antibodies specific for a pathogen or toxin are transferred to non-immune individuals. ...


Mortality from infectious diseases

The World Health Organization collects information on global deaths by International Classification of Disease (ICD) code categories. The following table lists the top infectious disease killers which caused more than 100,000 deaths in 2002 (estimated). 1993 data is included for comparison. “WHO” redirects here. ... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ...

Worldwide mortality due to infectious diseases[6]
Rank Cause of death Deaths 2002 Percentage of
all deaths
Deaths 1993 1993 Rank
N/A All infectious diseases 14.7 million 25.9% 16.4 million 32.2%
1 Lower respiratory infections[7] 3.9 million 6.9% 4.1 million 1
2 HIV/AIDS 2.8 million 4.9% 0.7 million 7
3 Diarrheal diseases[8] 1.8 million 3.2% 3.0 million 2
4 Tuberculosis (TB) 1.6 million 2.7% 2.7 million 3
5 Malaria 1.3 million 2.2% 2.0 million 4
6 Measles 0.6 million 1.1% 1.1 million 5
7 Pertussis 0.29 million 0.5% 0.36 million 7
8 Tetanus 0.21 million 0.4% 0.15 million 12
9 Meningitis 0.17 million 0.3% 0.25 million 8
10 Syphilis 0.16 million 0.3% 0.19 million 11
11 Hepatitis B 0.10 million 0.2% 0.93 million 6
12-17 Tropical diseases (6)[9] 0.13 million 0.2% 0.53 million 9, 10, 16-18
Note: Other causes of death include maternal and perinatal conditions (5.2%), nutritional deficiencies (0.9%),
noncommunicable conditions (58.8%), and injuries (9.1%).

The top three single agent/disease killers are HIV/AIDS, TB and malaria. While the number of deaths due to nearly every disease have decreased, deaths due to HIV/AIDS have increased fourfold. Childhood diseases include pertussis, poliomyelitis, diphtheria, measles and tetanus. Children also make up a large percentage of lower respiratory and diarrheal deaths. While often used as a synonym for pneumonia, the rubric of lower respiratory tract infection can also be applied to other types of infection including lung abscess, acute bronchitis, and empyema. ... Species Human immunodeficiency virus 1 Human immunodeficiency virus 2 Human immunodeficiency virus (HIV) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS, a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections). ... For other uses, see AIDS (disambiguation). ... Gastroenteritis involves diarrhea or vomiting, with noninflammatory infection of the upper small bowel, or inflammatory infection of the colon, both part of the gastrointestinal tract. ... Tuberculosis (abbreviated as TB for tubercle bacillus or TuBerculosis) is a common and deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. ... Malaria is a vector-borne infectious disease caused by protozoan parasites. ... Pertussis, also known as whooping cough, is a highly contagious disease caused by the bacterium Bordetella pertussis; a similar, milder disease is caused by B. parapertussis. ... Tetanus is a medical condition that is characterized by a prolonged contraction of skeletal muscle fibers. ... Meningitis is the inflammation of the protective membranes covering the central nervous system, known collectively as the meninges. ... Syphilis is a sexually transmitted disease caused by Treponema pallidum. ... “HBV” redirects here. ... Tropical diseases are infectious diseases that either occur uniquely in tropical and subtropical regions (which is rare) or, more commonly, are either more widespread in the tropics or more difficult to prevent or control. ... Species Human immunodeficiency virus 1 Human immunodeficiency virus 2 Human immunodeficiency virus (HIV) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS, a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections). ... For other uses, see AIDS (disambiguation). ... Tuberculosis (abbreviated as TB for tubercle bacillus or TuBerculosis) is a common and deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. ... Malaria is a vector-borne infectious disease caused by protozoan parasites. ... Pertussis, also known as whooping cough, is a highly contagious disease caused by the bacterium Bordetella pertussis; a similar, milder disease is caused by B. parapertussis. ... This article is about the disease. ... Tetanus is a medical condition that is characterized by a prolonged contraction of skeletal muscle fibers. ...


Historic pandemics

A young Bangladeshi girl infected with smallpox (1973). Thanks to the development of the smallpox vaccine, the disease was officially eradicated in 1979.

A pandemic (or global epidemic) is a disease that affects people over an extensive geographical area. Image File history File links Download high-resolution version (700x1066, 104 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Infectious disease ... Image File history File links Download high-resolution version (700x1066, 104 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Infectious disease ... A vaccine is an antigenic preparation used to establish immunity to a disease. ... This page is a candidate to be moved to Wiktionary. ... This article is about large epidemics. ... In epidemiology, an epidemic (from [[Latin language] epi- upon + demos people) is a disease that appears as new cases in a given human population, during a given period, at a rate that substantially exceeds what is expected, based on recent experience (the number of new cases in the population during...

  • Plague of Justinian, from 541 to 750, killed between 50 and 60 percent of Europe's population.[10]
  • The Black Death of 1347 to 1352 killed 25 million in Europe over 5 years (estimated to be between 25 and 50% of the populations of Europe, Asia, and Africa - the world population at the time was 500 million).
  • The introduction of smallpox, measles and typhus to the areas of Central and South America by European explorers during the 15th and 16th centuries caused pandemics among the native inhabitants. Between 1518 and 1568 disease pandemics are said to have caused the population of Mexico to fall from 20 million to 3 million.[11]
  • The first European influenza epidemic occurred between 1556 and 1560, with an estimated mortality rate of 20%.[11]
  • Smallpox killed an estimated 60 million Europeans in the 18th century alone. Up to 30% percent of those infected, including 80% of the children under 5 years of age, died from the disease, and one third of the survivors went blind. [12]
  • The Influenza Pandemic of 1918 (or the Spanish Flu) killed 25-50 million people (about 2% of world population of 1.7 billion).[13] Today Influenza kills about 250,000 to 500,000 worldwide each year.

The Plague of Justinian (541-542) is the first known pandemic on record, and it also marks the first firmly recorded pattern of bubonic plague. ... This article concerns the mid fourteenth century pandemic. ... Smallpox (also known by the Latin names Variola or Variola vera) is a contagious disease unique to humans. ... For the unrelated disease caused by Salmonella typhi, see Typhoid fever. ... Influenza, commonly known as flu, is an infectious disease of birds and mammals caused by an RNA virus of the family Orthomyxoviridae (the influenza viruses). ... Smallpox (also known by the Latin names Variola or Variola vera) is a contagious disease unique to humans. ... The 1918 flu pandemic, commonly referred to as the Spanish flu, was a category 5 influenza pandemic caused by an unusually severe and deadly Influenza A virus strain of subtype H1N1. ... Influenza, commonly known as flu, is an infectious disease of birds and mammals caused by an RNA virus of the family Orthomyxoviridae (the influenza viruses). ...

Emerging diseases and pandemics

In most cases, microorganisms live in harmony with their hosts. Such is the case for many tropical viruses and the insects, monkeys, or other animals in which they have lived and reproduced. Because the microbes and their hosts have co-evolved, the hosts gradually become resistant to the microorganisms. When a microbe jumps from a long-time animal host to a human being, it may cease to be a harmless parasite and become pathogenic.[14] Bumblebees and the flowers they pollinate have co-evolved so that both have become dependent on each other for survival. ...


With most new infectious diseases, some human action is involved, changing the environment so that an existing microbe can take up residence in a new niche. When that happens, a pathogen that had been confined to a remote habitat appears in a new or wider region, or a microbe that had infected only animals suddenly begins to cause human disease. A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... Two lichenes species on a rock, in two different ecological niches In ecology, a niche is a term describing the relational position of a species or population in an ecosystem. ... A pathogen or infectious agent is a biological agent that causes disease or illness to its host. ...


Several human activities have led to the emergence and spread of new diseases,[14] see also Globalization and Disease: Globalization, the flow of information, goods, capital and people across political and geographic boundaries, has also helped to spread some of the deadliest infectious diseases known to humans. ...

  • Encroachment on wildlife habitats. The construction of new villages and housing developments in rural areas brings people into contact with animals--and the microbes they harbor.
  • Changes in agriculture. The introduction of new crops attracts new crop pests and the microbes they carry to farming communities, exposing people to unfamiliar diseases.
  • The destruction of rain forests. As countries make use of their rain forests, by building roads through forests and clearing areas for settlement or commercial ventures, people encounter insects and other animals harboring previously unknown microorganisms.
  • Uncontrolled urbanization. The rapid growth of cities in many developing countries tends to concentrate large numbers of people into crowded areas with poor sanitation. These conditions foster transmission of contagious diseases.
  • Modern transport. Ships and other cargo carriers often harbor unintended "passengers", that can spread diseases to faraway destinations. While with international jet-airplane travel, people infected with a disease can carry it to distant lands, or home to their families, before their first symptoms appear.

Look up habitat in Wiktionary, the free dictionary. ... A rainforest is a forested biome with high annual rainfall. ...

The study of infectious disease

History

German postage stamps depicting four antique microscopes. Advancements in microscopy were essential to the early study of infectious diseases.

Abū Alī ibn Sīnā (Avicenna) discovered the contagious nature of infectious diseases in the early 11th century, for which he is considered the father of modern medicine. He introduced quarantine as a means of limiting the spread of contagious and infectious diseases in The Canon of Medicine, circa 1020.[15] He also stated that bodily secretion is contaminated by foul foreign earthly bodies before being infected, but he did not view them as primary causes of disease.[16] Image File history File linksMetadata Download high-resolution version (862x1412, 193 KB) Other versions unknown File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File linksMetadata Download high-resolution version (862x1412, 193 KB) Other versions unknown File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... A selection of Hong Kong postage stamps A postage stamp is evidence of pre-paying a fee for postal services. ... Robert Hookes microscope (1665) - an engineered device used to study living systems. ... (c. ... This article is about the medical term. ... As a means of recording the passage of time, the 11th century was that century which lasted from 1001 to 1100. ... This article does not cite any references or sources. ... A Latin copy of the Canon of Medicine, dated 1484, located at the P.I. Nixon Medical Historical Library of The University of Texas Health Science Center at San Antonio. ... Events Hospice built in Jerusalem by Knights Hospitaller City of Saint-Germain-en-Laye founded Third Italian campaign of Henry II of Germany Canute the Great codifies the laws of England Births Harold II of England (approximate) Empress Agnes of Poitou, regent of the Holy Roman Empire (d. ... Secretion is the process of segregating, elaborating, and releasing chemicals from a cell, or a secreted chemical substance or amount of substance. ... This article is about the medical term. ...


When the Black Death bubonic plague reached al-Andalus in the 14th century, Ibn Khatima and Ibn al-Khatib hypothesized that infectious diseases are caused by microorganisms which enter the human body.[16] Such ideas became more popular in Europe during the renaissance, particularly through the writing of the Italian monk Girolamo Fracastoro.[17] This article concerns the mid fourteenth century pandemic. ... The bubonic plague or bubonic fever is the best-known variant of the deadly infectious disease caused by the enterobacteria Yersinia pestis. ... Al-Andalus is the Arabic name given the Iberian Peninsula by its Muslim conquerors; it refers to both the Caliphate proper and the general period of Muslim rule (711–1492). ... The Renaissance (French for rebirth, or Rinascimento in Italian), was a cultural movement in Italy (and in Europe in general) that began in the late Middle Ages, and spanned roughly the 14th through the 17th century. ... Girolamo Fracastoro (Fracastorius) (1478‑1553) was an Italian physician, scholar and poet. ...


Anton van Leeuwenhoek (1632-1723) advanced the science of microscopy, allowing for easy visualization of bacteria. Anton van Leeuwenhoek Anton van Leeuwenhoek (October 24, 1632 - August 30, 1723, full name Thonius Philips van Leeuwenhoek (pronounced Layewenhook) was a Dutch tradesman and scientist from Delft, Netherlands. ... See also: 1632 (novel) Events February 22 - Galileos Dialogue Concerning the Two Chief World Systems is published July 23 - 300 colonists for New France depart Dieppe November 8 - Wladyslaw IV Waza elected king of the Polish-Lithuanian Commonwealth after Zygmunt III Waza death November 16 - Battle of Lützen... Events February 16 - Louis XV of France attains his majority Births February 24 - John Burgoyne, British general (d. ... This article or section is not written in the formal tone expected of an encyclopedia article. ...


Louis Pasteur proved beyond doubt that certain diseases are caused by infectious agents, and developed a vaccine for rabies. Louis Pasteur (December 27, 1822 – September 28, 1895) was a French chemist best known for his remarkable breakthroughs in microbiology. ...


Robert Koch, provided the study of infectious diseases with a scientific basis known as Koch's postulates. For the American lobbyist, see Bobby Koch. ... Kochs postulates (or Henle-Koch postulates) are four criteria designed to establish a causal relationship between a causative microbe and a disease. ...


Edward Jenner, Jonas Salk and Albert Sabin developed effective vaccines for smallpox and polio, which would later result in the eradication and near-eradication of these diseases, respectively. Portrait of Edward Jenner Edward Jenner, FRS, (17 May 1749 – 26 January 1823) was an English country doctor who studied nature and his natural surroundings from childhood and practiced medicine in Berkeley, Gloucestershire, England. ... Jonas Edward Salk (October 28, 1914 – June 23, 1995) was an American physician and researcher best known for the development of the first successful polio vaccine (the eponymous Salk vaccine). ... This article or section does not adequately cite its references or sources. ... Smallpox (also known by the Latin names Variola or Variola vera) is a contagious disease unique to humans. ... Poliomyelitis (polio), or infantile paralysis, is a viral paralytic disease. ... This page is a candidate to be moved to Wiktionary. ...


Alexander Fleming discovered the world's first antibiotic Penicillin. Sir Alexander Fleming (6 August 1881 – 11 March 1955) was a Scottish biologist and pharmacologist. ... Staphylococcus aureus - Antibiotics test plate. ... For the Japanese rock band, see Penicillin (band). ...


Gerhard Domagk develops Sulphonamides, the first broad spectrum synthetic antibacterial drugs. Gerhard Johannes Paul Domagk (October 30, 1895 - April 24, 1964) was a German pathologist and bacteriologist and Nobel laureate. ... Sulfonamides, also known as sulfa drugs, are synthetic antimicrobial agents derived from sulfonic acid. ... Generally, synthetic means pertaining to synthesis, i. ...


Medical specialists

The medical treatment of infectious diseases falls into the medical field of Infectiology and in some cases the study of propagation pertains to the field of Epidemiology. Generally, infections are initially diagnosed by primary care physicians or internal medicine specialists. For example, an "uncomplicated" pneumonia will generally be treated by the internist or the pulmonologist (lung physician).The work of the infectiologist therefore entails working with both patients and general practitioners, as well as laboratory scientists, immunologists, bacteriologists and other specialists.. For the chemical substances known as medicines, see medication. ... Epidemiology is the study of factors affecting the health and illness of populations, and serves as the foundation and logic of interventions made in the interest of public health and preventive medicine. ... An infection is the detrimental colonization of a host organism by a foreign species. ... Primary care may be provided in community health centres. ... Doctors of internal medicine (internists) are medical specialists who focus on adult medicine and have had special study and training focusing on the prevention and treatment of adult diseases. ... This article is about human pneumonia. ... Internal medicine is concerned with the diagnosis and treatment of internal diseases, that is, those that affect internal organs or the body as a whole. ... In medicine, pulmonology is the specialty that deals with diseases of the lungs and the respiratory tract. ... This article is about the concept. ... Immunology is a broad branch of biomedical science that covers the study of all aspects of the immune system in all organisms. ... Microbiology (in Greek micron = small and biologia = studying life) is the study of microorganisms, including unicellular (single-celled) eukaryotes and prokaryotes, fungi, and viruses. ...


An infectious disease team may be alerted when:

Immunosuppression is the medical suppression of the immune system. ... For other uses, see AIDS (disambiguation). ... Chemotherapy is the use of chemical substances to treat disease. ... In medicine, infectious disease or communicable disease is disease caused by a biological agent (e. ... Tropical diseases are infectious diseases that either occur uniquely in tropical and subtropical regions (which is rare) or, more commonly, are either more widespread in the tropics or more difficult to prevent or control. ... Staphylococcus aureus - Antibiotics test plate. ...

See also

Wikimedia Commons has media related to:
Infectious diseases

Image File history File links Commons-logo. ... An infection is the detrimental colonization of a host organism by a foreign species. ... An agar plate streaked with microorganisms Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. ... Human infectious diseases grouped by causative agent and alphabetically arranged. ... Copenhagen Consensus is a project which seeks to establish priorities for advancing global welfare using methodologies based on the theory of welfare economics. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In public health, a big killer is a disease or other major cause of loss of human life. ... // Nosocomial infections are those which are a result of treatment in a hospital or a healthcare service unit, but secondary to the patients original condition. ... Infection control and health care epidemiology is the discipline con setting. ... In recent years it has become obvious that there is a need to accommodate the growing integration of quantitative methods with the increasing volume of data being generated on host-pathogen interactions. ... Waterborne diseases are caused by pathogenic microorganisms which are directly transmitted when contaminated drinking water is consumed. ... A foodborne illness (also foodborne disease) is any illness resulting from the consumption of food. ... A blood-borne disease is one that can be spread by contamination by blood. ...

Notes and references

  1. ^ Dorland's Illustrated Medical Dictionary 2004 WB Saunders.
  2. ^ a b "Infectious disease." McGraw-Hill Encyclopedia of Science and Technology. The McGraw-Hill Companies, Inc., 2005.
  3. ^ Glossary of Notifiable Conditions Washington State Department of Health
  4. ^ a b This section incorporates public domain materials included in the text: Medical Microbiology Fourth Edition: Chapter 8 (1996) . Baron, Samuel MD. The University of Texas Medical Branch at Galveston.
  5. ^ Kenneth J. Ryan and C. George Ray, Sherris Medical Microbiology Fourth Edition McGraw Hill 2004.
  6. ^ The World Health Report - 2004 Annex Table 2 (pdf) and 1995 Table 5 (pdf-large!)
  7. ^ Lower respiratory infections include various pneumonias, influenzas and bronchitis.
  8. ^ Diarrheal diseases are caused by many different organisms, including cholera, botulism, and E. coli to name a few. See also: Intestinal infectious diseases
  9. ^ Tropical diseases include Chagas disease, dengue fever, lymphatic filariasis, leishmaniasis, onchocerciasis, schistosomiasis and trypanosomiasis.
  10. ^ Infectious and Epidemic Disease in History
  11. ^ a b Dobson, Andrew P. and E. Robin Carter (1996) Infectious Diseases and Human Population History (full-text pdf) Bioscience;46 2.
  12. ^ Smallpox: The Triumph over the Most Terrible of the Ministers of Death
  13. ^ Influenza of 1918 (Spanish Flu) and the US Navy
  14. ^ a b H. Krauss, A. Weber, M. Appel, B. Enders, A. v. Graevenitz, H. D. Isenberg, H. G. Schiefer, W. Slenczka, H. Zahner: Zoonoses. Infectious Diseases Transmissible from Animals to Humans. 3rd Edition, 456 pages. ASM Press. American Society for Microbiology, Washington DC., USA. 2003. ISBN 1-55581-236-8
  15. ^ David W. Tschanz, MSPH, PhD (August 2003). "Arab Roots of European Medicine", Heart Views 4 (2).
  16. ^ a b Ibrahim B. Syed, Ph.D. (2002). "Islamic Medicine: 1000 years ahead of its times", Journal of the Islamic Medical Association 2, p. 2-9.
  17. ^ Beretta M (2003). "The revival of Lucretian atomism and contagious diseases during the renaissance". Medicina nei secoli 15 (2): 129-54. PMID 15309812. 

This article is about human pneumonia. ... Influenza, commonly known as flu, is an infectious disease of birds and mammals caused by an RNA virus of the family Orthomyxoviridae (the influenza viruses). ... Bronchitis is an inflammation of the bronchi (medium-size airways) in the lungs. ... Cholera (or Asiatic cholera or epidemic cholera) is a severe diarrheal disease caused by the bacterium Vibrio cholerae. ... Botulism (Latin, botulus, sausage) is a rare, but serious paralytic illness caused by a nerve toxin, botulin, that is produced by the bacterium Clostridium botulinum. ... Binomial name Escherichia coli T. Escherich, 1885 Escherichia coli (usually abbreviated to E. coli) is one of the main species of bacteria that live in the lower intestines of warm-blooded animals (including birds and mammals) and are necessary for the proper digestion of food. ... “Dengue Fever” redirects here. ... See special page for Filariasis in domestic animals Lymphatic Filariasis is a parasitic and infectious tropical disease, caused by three thread-like parasitic filarial worms, Wuchereria bancrofti, Brugia malayi, and Brugia timori, all transmitted by mosquitoes. ... Binomial name Onchocerca volvulus Bickel 1982 Onchocerciasis (pronounced ) or river blindness is the worlds second leading infectious cause of blindness. ... Schistosomiasis or bilharzia is a disease affecting many people in developing countries. ... Trypanosomiasis is the name of the diseases caused by parasitic protozoan trypanosomes of the genus trypanosoma in vertebrates. ... The Islamic Medical Association of North America (IMANA) is the largest Muslim medical organization in North America. ...

External links


  Results from FactBites:
 
Infectious disease - Wikipedia, the free encyclopedia (1676 words)
In medicine, infectious disease or communicable disease is disease caused by a biological agent such as by a virus, bacterium or parasite.
Infectious diseases are the invasion of a host organism by a foreign replicator, generally microorganisms, often called microbes, that are invisible to the naked eye.
For infectious diseases it helps to determine if a disease outbreak is sporadic (occasional occurrence), endemic (regular cases often occurring in a region), epidemic (an unusually high number of cases in a region), or pandemic (a global epidemic).
Infectious Disease (2270 words)
Infectious disease is classified as acute (occurs over a relatively short time period like a cold or the flu) or chronic (when the pathogen evades the immune system and persists in the body for months to years as in Lyme disease or tuberculosis).
Diseases are spread in characteristic ways depending on the part of the body infected and the biology of the pathogen.
Infectious diseases are diagnosed by culture and biochemical characteristics, immunological tests for antigen types, and PCR and nucleic acid hybridization for genotype similarity.
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