Parasitology

thumb|upright=1.35|A fish parasite, the isopod [[Cymothoa exigua, replacing the tongue of a Lithognathus]]

right|thumb|250px|Adult black fly (Simulium yahense) with [[Onchocerca volvulus emerging from the insect's antenna. The parasite is responsible for the disease known as river blindness in Africa. Sample was chemically fixed and critical point dried, then observed using conventional scanning electron microscopy. Magnified 100×.]] Parasitology is the study of parasites, their hosts, and the relationship between them. As a biological discipline, the scope of parasitology is not determined by the organism or environment in question but by their way of life. This means it forms a synthesis of other

organism that harbors another organism; organism whose resources are used by another organism then called parasite

agent that carries and transmits an infectious pathogen into another living organism

thumb|upright=1.2|A parasitoid wasp (Trioxys complanatus, [[Aphidiinae) ovipositing into the body of a spotted alfalfa aphid (Therioaphis maculata, Calaphidinae), a behaviour that is used in biological pest control]]

thumb|upright=1.35|Great frigatebirds (Fregata minor) chasing a [[red-footed booby (Sula sula) to steal its food]] Kleptoparasitism (originally spelt clepto-parasitism, meaning "parasitism by theft") is a form of feeding behavior in which one animal — i.e. the kleptoparasite — deliberately takes food from another animal, often via aggressive confrontations. The strategy is evolutionarily stable when stealing is less costly than direct predation, such as when food is scarce or when physically weaker/less assertive victims are abundant and unlikely to fight back.

disease transmission via particles containing fecal pathogens

A trophozoite (G. trope, nourishment + zoon, animal) is the activated, feeding stage in the life cycle of certain protozoa such as malaria-causing Plasmodium falciparum and those of the Giardia group. The complementary form of the trophozoite state is the thick-walled cyst form. They are often different from the cyst stage, which is a protective, dormant form of the protozoa. Trophozoites are often found in the host's body fluids and tissues and in many cases, they are the form of the protozoan that causes disease in the host. In the protozoan, Entamoeba histolytica it invades the intestinal m

parasitic disease of vertebrates

method of biological control

thumb | right | alt=A photomicrograph of a blood smear containing a macrogametocyte of the parasite Plasmodium falciparum. | A photomicrograph of a blood smear containing a macrogametocyte of the parasite Plasmodium falciparum Parasitemia is the quantitative content of parasites in the blood. It is used as a measurement of parasite load in the organism and an indication of the degree of an active parasitic infection. Systematic measurement of parasitemia is important in many phases of the assessment of disease, such as in diagnosis and in the follow-up of therapy, particularly in the chronic p

Any mechanism of immune avoidance that directly affects the host immune system, e.g. blocking any stage in host MHC class I and II presentation. The host is defined as the larger of the organisms involved in a symbiotic interaction.

bacterium cause of many diseases

museum in Tokyo, Japan

thumb|Melampsora laricis-populina life cycle. (a) Biological macrocyclic heteroecious cycle of M. larici-populina. (b) Vegetative cycle occurring on poplar leaves and used as a model for molecular investigations of the poplar-[[poplar rust interaction. hpi=hours of postinoculation.]] A heteroecious parasite is one that requires at least two hosts. The primary host is the host in which the parasite spends its adult life; the other is the secondary host. Both hosts are required for the parasite to complete its life cycle. This can be contrasted with an autoecious parasite which can complete its

thumb|Schistosoma haematobium egg

relationship between organisms

thumb|Tachyzoites of [[Toxoplasma gondii, transmission electron microscopy. Micronemes: mn (click to enlarge)]] Micronemes are secretory organelles, possessed by parasitic apicomplexans. Micronemes are located on the apical third of the protozoan body. They are surrounded by a typical unit membrane. On electron microscopy they have an electron-dense matrix due to the high protein content. They are specialized secretory organelles important for host-cell invasion and gliding motility.

the trend of social parasites to be parasites to species or genera they are closely related to

the strategy by a parasite of blocking reproduction by its host (completely or in part) to its own benefit

adaptation of pathogens to reduce the protection of vaccines