Glossary

All definitions in this glossary are provided within the context of veterinary parasitology.

The meaning of a term may differ in other contexts, including non-scientific, non-clinical and general usage.

A
Aberrant host An organism that harbours a parasite that normally infects a completely different species.

Acaricidal compound Compounds that act against ectoparasites belonging to the class Arachnida, sub-class Acari by zoological nomenclature.

Acaricide Compounds that act against ectoparasites belonging to the class Arachnida, sub-class Acari by zoological nomenclature.

Adulticide Compounds that act against adult insects.

Amastigote Non-motile parasitic forms, in the life cycle of some protozoans, that usually develop in the cells of vertebrate hosts.

Anaphylaxis An extreme and dangerous allergic reaction.

Anthelmintic A compound that destroys or causes the expulsion of parasitic worms.

Anthelmintic resistance The ability of a worm population to survive the standard recommended and effective dose of an anthelmintic; this is a heritable trait.

Antigen A foreign substance which induces an immune response in the body, especially by producing antibodies.

Apathogenic Not capable of causing disease.

Application Like treatment, but describing how veterinary medicinal products can be administered or applied to animals, typically orally, topically or by injection.

Ascarid A worm of the family Ascarididae which includes Ascaridia, Ascaris, Toxocara and Toxascaris.

Asexual reproduction Multiplication of parasite stages by binary or multicellular fission without production of sexually differentiated stages.

Asymptomatic Capable of carrying and transmitting disease but exhibiting no symptoms or clinical signs.

Atopic The animal is allergic or sensitised to antigens from the environment.

Autoimmune disease A disease or condition where the body’s immune system mistakenly attacks its own tissues or cells, causing inflammation and damage.

B
Binary fission Asexual reproduction by means of a cell or organism dividing into two or more new cells or organisms.

Bradyzoites Slow-dividing tissue stages contained within a pseudocyst or maturating tissue cyst.

C
Cerumen Earwax.

Cestodes Any of the various flatworms of the class Cestoidea, including tapeworms.

Chemoprophylaxis Disease prevention by the use of chemicals or drugs.

Chemotherapy Disease treatment by use of chemicals.

Control General term comprising therapy and prevention (prophylaxis).

Coproantigen test Test to detect antigen in faeces.

Cysts a) Environmental resistant stage of Giardia excreted with faeces able to survive outside the host. b) Mature stage of heteroxenic protozoa in the extraintestinal tissues (= tissue cysts).

D
Definitive/final host A host in which the sexual development (production of sexually differentiated stages) is completed (in contrast to intermediate hosts).

Dermatoses Any skin disease or lesion on the skin.

Dormozoites Sleeping cells – non-dividing tissue stages. Development continues once they are transmitted to a carnivorous host until they are transmitted to a carnivorous host.

E
Ectoparasiticide Compound developed as a therapeutic agent to eliminate any existing ectoparasite infestation and prevent reinfestation.

Efficacy The ability of a drug to produce the desired therapeutic effect at the recommended dosage.

Egg re-appearance period (ERP) The time interval between the last effective anthelmintic treatment and the reappearance of egg shedding.

Eggs per gram (EPG) The number of helminth (usually nematode) eggs per gram of faeces from an animal.

Endemic Prevalent in, or restricted to, a particular region.

Endoparasiticide Therapeutic agent used to eliminate an endoparasite infection and to prevent reinfection.

Epidemiology The study of the causes, distribution and control of disease.

Erythematous Red skin due to congestion of the capillaries.

Excystation Escape of parasite stages from the multilayered shell which cover the environmental stages (see cyst, oocyst).

F
Faecal egg count reduction test (FECRT) A test to assess treatment efficacy based on pre- and posttreatment faecal egg counts.

Filaria Nematode worms now classified as Onchocercidae.

Filarial Relating to nematode worms now classified as Onchocercidae.

Filarioid Parasitic nematodes (roundworms) belonging to the family Onchocercidae.

Flavivirus A genus of viruses that cause serious diseases such as West Nile virus, dengue virus, tick-borne encephalitis virus, yellow fever virus, Zika virus and several other viruses which may cause encephalitis.

G
Gametocyte A gametocyte is a sexual precursor cell that develops into a gamete (sperm or egg) during the sexual stage of the life cycle of certain parasites.

Gamont A particular life cycle stage of protozoa. Gamonts give rise to gametes which unite in pairs to form zygotes.

Gastrointestinal Relating to both the stomach and the intestine.

Genotype The genetic makeup of an organism.

Gram-negative A staining technique for the preliminary identification of bacteria, in which a violet dye is applied, followed by a decolourising agent and then a red dye. The cell walls of certain bacteria (denoted Gram-positive) retain the first dye and appear violet, while those that lose it (denoted Gram-negative) appear red.

Gram-positive A staining technique for the preliminary identification of bacteria, in which a violet dye is applied, followed by a decolourising agent and then a red dye. The cell walls of certain bacteria (denoted Gram-positive) retain the first dye and appear violet, while those that lose it (denoted Gram-negative) appear red.

Granuloma A localised area of inflammation and immune cell aggregation that forms in response to a persistent stimulus, such as infection or a foreign body.

H
Haematology The scientific study of blood and blood components.

Haemoprotozoa Single-celled protozoan parasites which inhabit the bloodstream of their living host, whether intracellular or extracellular.

Helminths Worms: in this context parasitic.

Heteroxenic/heteroxenous Infecting several host species in the life cycle.

Histology The microscopic study of the structure of tissue and cells.

Homoxenic Infecting only one host in the whole life cycle.

Hookworm Parasitic nematode with hooked mouthparts.

Host An organism that harbours parasites.

Hyperpigmentation An increase in the natural colour of the skin.

Hypnozoites See dormozoites.

Hypobiosis Arrested development, normally in worm larval stages in the intestinal mucosa of the definitive host.

Hypostome The harpoon-like structure that forms part of the mouthparts of certain parasitic arthropods including ticks, that allows them to anchor themselves firmly in place on a host vertebrate while sucking blood.

I
IGR (insect growth regulator) Compound that may kill and/or inhibit the development of immature stages of insects.

Immune-mediated A disease or condition in which the immune system plays a role in its origin or development.

Incubation In parasitology, the period of time from parasite exposure to the onset of clinical symptoms.

Indirect detection methods Serological methods which determine previous contact to parasites by detection of specific antibodies induced by infection. As antibodies are usually produced some time after initial infection and prevail after parasite clearance, they do not necessarily indicate the presence of active infections. Antibody detection can be performed in different formats, e.g. Western blotting, direct or indirect immunofluorescence assays, ELISA, lateral flow assays and others. Detection is accomplished by the use of labelled secondary antibodies. Many, but not all, of these tests allow for a quantification of antibody levels (titres) e.g. for follow-up studies during the course of infection or treatment.

Infection Invasion and multiplication of micro-organisms in body tissues.

Infective Capable of producing infection.

Infestation The presence of parasites in the environment, on the skin or in the hair of a host.

Ingestion Taking into the body via the mouth.

Insect-borne Insect-borne diseases are infections transmitted by insects.

Insecticide/insecticidal compound Compounds that act against ectoparasites belonging to the class Insecta by zoological nomenclature.

Integrated control The use of several measures to control different parasites, or parasite stages, present on the animal as well as stages present in the environment.

Intermediate host A host in which asexual reproduction or development is completed.

Intertriginous Areas of skin that may rub together e.g. the axilla between the leg and body of an animal.

Intracellular Within the cell.

K
Kinete A particular life cycle stage produced in the midgut cells of ticks or mosquitoes. They migrate directly to the tick's salivary glands or mosquito’s mouthparts where they develop into infective sporozoites.

L
L1 – L2 – L3 – L4 – L5 or pre-adult This is the normal larval development sequence of nematodes, beginning with the first larval stage (L1) which moults four times to the pre-adult stage. Generally, the development of nematodes from first stage larvae (L1) to third stage larvae (L3) occurs in the environment or in an intermediate host and the fourth stage larvae (L4), L5 or pre-adult and adult within the host.

Larvae The active immature form of an insect, especially one that differs greatly from the adult and forms the stage between egg and pupa.

Lichenification Thickening of the skin caused by chronic inflammation resulting from prolonged scratching or irritation.

Lymphocyte A form of small leucocyte (white blood cell) with a single round nucleus, occurring especially in the lymphatic system, but also in the bloodstream.

M
Macrophage Specialised cells involved in the detection and destruction of harmful organisms within the body.

Merozoite A protozoan cell that may become either a meront or a gamont.

Metacestode The larval stage of a tapeworm that infects an intermediate host and is capable of infecting the definitive host.

Metaphylactic measures Measures given to infected, but not yet sick or damaged, host animals taken to prevent or minimise an expected disease.

Metastrongylids Family of nematode parasites, the adults invade the bronchi and lung.

Microfilaria/microfilariae An early stage (minute or pre larva) in the life cycle of certain parasitic nematode worms. Sometimes abbreviated to "mf". Plural: microfilariae.

Microscopy The use of microscopes.

Monocyte A type of leukocyte or white blood cell with a simple oval nucleus and clear, greyish cytoplasm.

Monotherapy Therapy that uses one type of treatment to treat a certain disease or condition.

Monoxenous Infecting only one host species in the whole life cycle.

Morphology The form and structure of organisms.

Morulae A solid ball of cells resulting from division of a fertilised ovum, and from which a blastula is formed (singular: morula).

Motile Moving.

Multifocal Existing in more than one place in the body or part of the body.

Myiasis Infection of vertebrates by developing fly larvae.

N
Nematodes Roundworms, in this context parasitic.

Neutrophil A type of granulocyte or white blood which forms an essential part of the innate immune system.

Non-motile Not exhibiting or capable of movement.

Nymph The immature stage of certain arthropods, particularly ticks and mites, that undergo incomplete metamorphosis without a pupal stage, resembling the adult form but with underdeveloped reproductive organs and wings.

O
Oocyst A tenacious spore stage capable of surviving outside the host.

P
Palaearctic A zoogeographical region consisting of Europe, Africa (north of the Sahara) and most of Asia (north of the Himalayas).

Parasite burden The number of parasites a host organism harbours, a key factor in determining the severity of parasitic infections.

Parasiticide A compound developed for killing parasites.

Parasitoses Diseases or conditions caused by parasitic infections.

Paratenic host A host which serves to maintain the life cycle of the parasite; no parasite development or reproduction takes place.

Patent infection A mature infection which produces immature stages such as eggs or oocysts.

Patent period Time period during which the parasites are sexually mature and produce offspring (e.g. eggs or larval stages), ending when they cease to reproduce or with their death.

Pathogen An agent capable of causing disease.

Pathogenesis The origin, development and resultant effects of a disease.

Pathogenic Relating to an agent that is capable of causing disease.

PCR (polymerase chain reaction) A molecular technique used to detect and identify parasite DNA, enabling more sensitive and accurate diagnosis of parasitic infections than traditional methods like microscopy.

Pentastomid Worm-like arthropods that are obligate endoparasites of the respiratory tract of vertebrates.

Peracute A condition or disease that is severe and has a very rapid, sudden onset and progression, often leading to a rapidly fatal outcome.

Pesticide A compound developed for the elimination of different stages of parasites in the environment.

Phagocyte A type of immune cell that has the ability to engulf and devour foreign particles.

Phagocytize When a phagocyte cell engulfs and devours a foreign material.

Phlebotome A sand fly. In Europe, Psychodid sand flies of the genus Phlebotomus are responsible for the transmission of leishmaniosis.

Piroplasm Vector-borne intracellular haemoprotozoan parasites.

Plasmid vector pPAL A non-replicative, antibiotic-free mammalian expression vector used for developing third-generation vaccines, including therapeutic vaccines, and it induces immunomodulation based on the Th1 T-cell response.

Prepatency/prepatent period This is the time interval between infection of a definitive host with a parasite species and the first detection of eggs or larval stages in the faeces.

Prevalence A term describing the proportion (usually given as a percentage) of infected hosts within any group of animals.

Prevalence A term describing the proportion (usually given as a percentage) of infected hosts within any group of animals.

Prevention Measures taken, prior to any parasitic infestation or infection of the animal, to prevent the establishment of an infestation, infection or disease.

Proboscis In insects etc it is an elongated sucking mouthpart used for feeding.

Proglottids Segments of a tapeworm.

Promastigote Motile, elongated, extracellular form in the life cycle of some protozoans.

Prophylactic Measures taken to prevent or reduce the risk of infection.

Protoscolices The juvenile, infective stages of tapeworms (cestodes), particularly those of the genus Echinococcus, which develop within hydatid cysts and are capable of developing into adult worms in the definitive host.

Protozoa Any of a large group of single-celled organisms.

Pruritus Severe itching.

R
Recombinant protein Artificially produced proteins using genetic engineering techniques, often used for research, diagnostics, and vaccine development by expressing parasite genes in a different host.

Refugium The parasite population that is not exposed to the drug at the time of treatment.

Repellency The ability of a substance or treatment to deter or prevent parasites, like ticks or mosquitoes, from attaching, biting, or feeding on a host, essentially causing them to avoid a treated area or host.

Repellent A compound which makes a host unattractive to a parasite and thus can prevent attack or establishment.

Reservoir host An animal that harbours a parasite, often without showing any signs of illness, and serves as a source of infection for other susceptible species.

Resistance The capacity to withstand the effects of a harmful chemical agent.

Resistant Something that has the capacity to withstand the effects of a harmful chemical agent.

S
Schizogony See asexual reproduction.

Scutum A hard, shield-like plate or scale covering the dorsal (back) surface of hard ticks.

Sensitivity The rate of true-positive samples (as judged by a “Gold Standard” test) or the likelihood that an infected animal can be detected as positive by the test.

Sensitivity [%] True-positive samples/(True-positive samples + False-negative samples)*100.

Seroconversion The change from a seronegative to a seropositive result owing to the development of specific antibodies in the blood serum as a result of infection or immunisation.

Serology The scientific study or diagnostic examination of blood serum, especially with regard to the response of the immune system to pathogens or introduced substances.

Seronegative Giving a negative result in a test of blood serum.

Seropositive Giving a positive result in a test of blood serum.

Specificity The rate of true-negative samples (as judged by a “Gold Standard” test) or the likelihood that an uninfected animal can be detected as negative by the test.

Specificity [%] True-negative samples/(True-negative samples + False-positive samples samples)*100.

Sporocysts A multilayered stage within oocysts that contains the sporozoites.

Sporozoites The cellular infective units that evolve from excystation of oocysts and sporocysts.

Sporulation Development of sporozoites from the stages of sexual development.

Subacute Between acute and chronic when relating to a condition.

Subclinical Relating to a disease which is not severe enough to present definite or observable symptoms or clinical signs.

Subcutaneous Under the skin. Subcutaneous worms = worms that burrow under the skin.

Sustained-release A formulation designed to slowly release a drug in the body over an extended period of time especially to sustain therapeutic levels.

Symbiosis Interaction between two different organisms living in close physical association, typically to the advantage of both.

Symptomatic Relating to, or based upon, symptoms.

T
Tachyzoites Fast-reproducing parasite stages within the host cell.

Therapy Any medical intervention to cure a disease; this includes the use of veterinary medicinal products (treatment), to eliminate an existing parasite infestation.

Tick-borne Tick-borne diseases are infections transmitted by ticks.

Tissue cyst See cysts.

Titre A measurement of the concentration of a substance in an amount of blood.

Topical treatment Treatment applied to the surface of the skin.

Transovarial transmission The transmission of pathogens from female parent to offspring.

Treatment Application of veterinary medicinal products (medication) as deemed necessary based upon any given diagnosis or risk.

Trematodes Flatworms, in this context parasitic.

Trophozoites Motile, active stages in the host e.g. within the life cycle of Giardia and other protozoa.

V
Vector An organism, typically a biting insect or tick, that transmits a pathogen or parasite from one animal or plant to another.

Vector-borne An organism, such as a mosquito or tick, that carries disease-causing micro-organisms from one host to another.

Venereal transmission Infections passed on through sexual contact.

Vertical transmission When the transmission of causative agents occurs from mothers to their offspring.

Viscera Soft internal organs of the body.

Visceral Relating to the viscera.

Vitreous The gel-like fluid that fills the eye's posterior cavity, the space between the lens and the retina, where parasites, like certain nematodes, can sometimes be found.

Z
Zoonosis Any infectious disease that can be transmitted between animals and humans.

Zoonotic Transmissible between animals and humans stages (see cyst, oocyst).

Zygote A diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum.

Glossary

Aberrant host

Acaricidal compound

Acaricide

Adulticide

Amastigote

Anaphylaxis

Anthelmintic

Anthelmintic resistance

Antigen

Apathogenic

Application

Ascarid

Asexual reproduction

Asymptomatic

Atopic

Autoimmune disease

Binary fission

Bradyzoites

Cerumen

Cestodes

Chemoprophylaxis

Chemotherapy

Control

Coproantigen test

Cysts

Definitive/final host

Dermatoses

Dormozoites

Ectoparasiticide

Efficacy

Egg re-appearance period (ERP)

Eggs per gram (EPG)

Endemic

Endoparasiticide

Epidemiology

Erythematous

Excystation

Faecal egg count reduction test (FECRT)

Filaria

Filarial

Filarioid

Flavivirus

Gametocyte

Gamont

Gastrointestinal

Genotype

Gram-negative

Gram-positive

Granuloma

Haematology

Haemoprotozoa

Helminths

Heteroxenic/heteroxenous

Histology

Homoxenic

Hookworm

Host

Hyperpigmentation

Hypnozoites

Hypobiosis

Hypostome

IGR (insect growth regulator)

Immune-mediated

Incubation

Indirect detection methods

Infection

Infective

Infestation

Ingestion

Insect-borne

Insecticide/insecticidal compound

Integrated control

Intermediate host

Intertriginous

Intracellular

Kinete

L1 – L2 – L3 – L4 – L5 or pre-adult

Larvae

Lichenification