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WNV Glossary of Terms

antigen: (noun) a usually protein or carbohydrate substance (as a toxin or enzyme) capable of stimulating an immune response. Adjective: antigenic. German, from French antigene, from anticorps = antibody + gene -gen (1908). An epitope (1960) or antigenic determinant (1950) is a molecular region on the surface of an antigen capable of eliciting an immune response and of combining with the specific antibody produced by such a response.

arbovirus: any of various RNA viruses transmitted by arthropods. I.e., "arboviruses" are not a taxonomic group. (from arthropod borne virus, 1957)

arthropod: invertebrate animals in the phylum Arthropoda, a group that have a segmented body, jointed appendages, a usually chitinous exoskeleton molted at intervals, and a dorsal anterior brain connected to a ventral chain of ganglia. Includes insects, arachnids, crustaceans. (New Latin from arth- + Greek pod-, pous foot, 1877)

carrier: CDC defines the term disease carrier as implying "prolonged or indefinite survival, viral excretion, and ability to transmit infection." [Definition given in the Centers for Disease Control MMWR October 25, 2002, 51(42):963 in context of clarifying that bats and other mammals are not carriers of the rabies virus.] Merriam Webster defines a disease carrier as "a bearer and transmitter of a causative agent of an infectious disease; especially one who carries the causative agent of a disease systemically but is immune to it, [or] an individual (as one heterozygous for a recessive) having a specified gene that is not expressed or only weakly expressed in a phenotype.

diptera: a large group (Order) of insects that are abundant almost everywhere and include mosquitoes, flies, gnats and midges. Diptera (from di = two and ptera = wing) are distinguished from other Orders of insects by having only one pair of wings, with the second pair instead reduced to small knobbed structures called "halteres" that aid in maintaining equilibrium. Some diptera are vectors of diseases such as malaria, yellow fever, filariasis, and the arboviruses, while others are important pollinators and pest predators and parasites. Diptera undergo complete metamorphosis, which means that they change form during development (see larvae and pupae.)

encephalitis: an inflammation of the brain that can be caused by viruses and bacteria, including viruses transmitted by mosquitoes. (1843)

endemic: (adjective) belonging or native to a particular people or country and thus continuously present at the expected frequency of occurrence; restricted or peculiar to a locality or region (endemic diseases; an endemic species). Synonym=Native. From the French endemique, from Greek en- = in + daemos = people, populace (1759).

enzootic: referring to animal diseases that are peculiar to or constantly present in a locality. From en- , in + epizootic (1882).

epidemic: (adjective) affecting or tending to affect a disproportionately large number of individuals within a population, community or region at the same time, i.e., at a higher than expected frequency. Used to refer to diseases that are not consistently present in an area, and which are brought in from the outside or a temporary increase in the number of cases of an endemic disease. From French epidemique, from Late Latin epidemia, from Greek epidaemos = visiting, from epi- + daemos = people (1603).

epidemiology: (noun) a branch of medical science that deals with the incidence, distribution, and control of disease in a population; or the sum of the factors controlling the presence or absence of a disease or pathogen. From Late Latin epidemia + International Science Vocabulary -logy (circa 1860).

gravid: (adjective) distended with or full of eggs, as in "mosquito trap for gravid females" also called "gravid trap." From Latin gravidus, from gravis = heavy (1597).

host: a living animal or plant affording subsistence or lodgment to a parasite. Parasites are organisms that are metabolically dependent upon the host. (14th century)

larva, plural = larvae: the immature stages between the egg and the pupa, of an insect with complete metamorphosis. The form of the insect during the larval stage differs radically from the adult.

larvicide: pesticides used to control insects at the larval stage of their development.

morbidity: (noun) the relative incidence of disease (circa 1721)

multivoltine: (adjective) having several broods in a season, as in "multivoltine species of mosquito." From multi- + -voltine = having a given number of broods, which is from French, from Italian volta = time, turn (1894).

predation: (noun) a mode of life in which food is primarily obtained by the killing and consuming of animals (15th century) .

predaceous: (adjective) living by preying on other animals: predatory. From Latin praedari, to prey upon (1713). E.g., mosquito fish are "predaceous" on mosquitoes.

pupa, plural = pupae: the immature stage between the larva and adult, of an insect with complete metamorphosis.

recrudescence: (noun) a new outbreak after a period of abatement or inactivity (1721). recrudesce: (intransitive verb) to break out or become active again (1884). From Latin recrudescere to become raw again, from re- + crudescere to become raw. E.g., Some scientists hypothesize that West Nile virus may be a chronic infection in birds that recrudesces during times of stress for the bird, such as migration, mating and when establishing territory.

reservoir: a population or group of populations of vertebrate or invertebrate hosts in which the pathogen is endemic (i.e., permanently maintained). Although human populations can form reservoirs of this kind, the concept is usually applied to non-human populations from which the pathogen periodically escapes, causing individual infections or epidemics in humans or epizootics in other animals. From Middle French, reserver (1690).

sequela, plural = sequelae: (noun) an after effect of disease or injury. A secondary result. New Latin, from Latin sequel (1793).

seroconversion: (noun) the production of antibodies in response to an antigen (1963).

seropositive: (adjective) having or being a positive serum reaction, especially in a test for the presence of an antibody (circa 1930).

seroprevalence survey: a standard tool used by public health officials. "Sero-" (from the Latin serum) refers to testing of blood for antibodies to an infectious organism; "prevalence" refers to the percentage of people with a particular characteristic at a given point in time. A "West Nile Virus Seroprevalence Survey" is a survey to determine the percentage of persons with antibodies to West Nile Virus, at a given point in time, within the geographic area sampled.

transovarial: with regard to West Nile Virus, used in phrase "transovarial transmission" and refers to capability of an infected mosquito to pass the virus to offspring, a process also known as vertical transmission. Infection in male mosquitoes would be attributed to transovarial transmission since male mosquitoes do not bite to get a blood meal.

vector: carrier of a pathogen from one host to another. In describing any species as a vector, what is meant is that some individuals of a species are capable of carrying a given pathogen. Because of genetic heterogeneity (differences) within species, it is generally not the case that all individuals in a species are competent vectors. From Latin vehere, to carry.

viremia: the presence of virus in the blood of a host. From New Latin: virus + -emia (1946). viremic (adjective).

zoonoses: diseases in which pathogens are harbored by other animals as well as by humans, and which are communicable from animals to humans under natural conditions. From New Latin, from zo- + Greek nosos disease (1876).