Toxoplasma


Also found in: Dictionary, Medical, Wikipedia.

Toxoplasma

 

a genus of parasitic protozoa that has one identified species, Toxoplasma gondii. Studies of the life cycle and ultrastructure of T. gondii have shown that it belongs to the order Coccidia.

In the epithelium of the small intestines of cats and other Felidae, the parasites of Toxoplasma proceed through a complex life cycle, which is completed with the formation of minute egglike oocysts similar to those of coccidia of the genus Isospora. Each oocyst contains two spores, each of which develops into four single-celled sporozoites. The mature sporulating oocysts may reinfect felines, in which case the oocysts undergo both asexual and sexual developmental cycles. When the sporulating oocysts enter other mammals, such as mice, as well as birds and man, the oocysts undergo only asexual multiple reproduction.

After entering the macrophages and various organs and tissues, predominantly those of the reticuloendothelial, muscle, and nervous systems, the sporozoites develop into highly fecund mononuclear trophozoites (endozoites) that multiply through a type of internal budding known as endodiogeny. The trophozoites are crescent in shape and measure 4–7 micrometers in length. Their ultrastructure is identical to that of such merozoites as coccidia.

In the chronic form of toxoplasmosis, cysts are formed in a number of organs, including the brain. These cysts contain up to several hundred mononuclear organisms, called cystozoites. The endozoites and cystozoites may infest new hosts, primarily by means of the alimentary tract. Toxoplasma is the source of toxoplasmosis, a severe disease of animals and man.

IU. I. POLIANSKII

References in periodicals archive ?
Toxoplasmosis snapshots: global status of Toxoplasma gondii seroprevalence and implications for pregnancy and congenital toxoplasmosis.
Toxoplasma can cause pregnant women to miscarry, although the parasite is otherwise thought to be harmless to healthy humans.
Diffusionweighted MRI of cerebral toxoplasma abscess.
For example, toxoplasma is an environmental contaminant spread by infected cats.
A child born with congenital toxoplasma is damaged for life.
Toxoplasma gondii seropozitivitesi gosteren insanlarda, sizofreni gorulme sikliginin daha fazla oldugu yapilan seroprevalans calismalariyla ortaya konmustur (13).
Brain biopsy demonstrated toxoplasma encephalitis which was confirmed by PCR examination of the brain tissue.
The single-celled organism Toxoplasma gondii infects about a third of the world's population.
The obligate intracellular protozoal parasite Toxoplasma gondii (reservoirs in faeces of the domestic cat) is the most common opportunistic CNS infection in patients with AIDS.
Their topics include the dense granule proteins of Toxoplasma gondii, new insights into the liver stage biology of malaria parasites, multi-locus sequence typing (MLST) and its applications in epidemiological studies for parasitic infections, the metabolism of poly-ADP-ribose in trypanosomatids, parasite control and livestock production in Nigeria, possible impacts of climate change on waterborne parasitic infections at northern latitudes, and the diagnosis of opportunistic parasites in liver transplantation.
The senior physician in reply to another question also urged people to ensure that only well and properly cook meat is consumed by them as otherwise they could be exposed to toxoplasma.