Chapter 6: Toxoplasma

MORÉ, G.; VENTURINI, M.C.; PARDINI, L.; UNZAGA, J.M.

Parasitic Protozoa of Farm Animals and Pets

Springer Nature

Año: 2018; p. 149 - 168

Toxoplasmosis is a zoonotic infection caused by the protozoa Toxoplasma gondii affecting animals worldwide. T. gondii has a facultative heteroxenous life cycle with felids as definitive host and a wide range of mammalian and avian species as intermediate hosts. Infectious stages are oocysts present in felid feces, bradyzoites forming tissue cysts and tachyzoites. While two major clonal lineages (type II and III) dominate clinical and natural isolates in Europe and North America, other parts of the world like Brazil and Argentina, are dominated by non-clonal or other clonal T. gondii lineages representing a greater genetic diversity of T. gondii. Different animal species showed different susceptibilities to T. gondii infection and to the developing of clinical signs. Humans are considered susceptible and about 1/3rd of the human population in the world is considered to be infected. Toxoplasmosis is an important abortive disease in small ruminants, is mainly asymptomatic in cattle and chickens, but the last are epidemiological sentinels since the isolation of viable parasites is frequent. Infected pigs could show reproductive failure and its tissues are considered, together with infected small ruminant tissues, as an important infection source to humans. Cats and dogs showed neuromuscular disease mainly associated with other immunosuppressive condition such as viral infections. Some species like New World monkeys, lemurs, Pallas? cats, slender-tailed meerkats and some Australian marsupials are highly susceptible to fatal generalized toxoplasmosis. General control measures are presented, focusing on prevent human toxoplasmosis.