Toxoplasma

Toxoplasma gondii is a protozoan parasite that can infect almost all warm-blooded animals, including humans.Weiss, Louis M. & Kami Kim, eds. 2011. Toxoplasma gondii: the model Apicomplexan: perspectives and methods. Academic Press/Elsevier, London, p49.<ref name=Dubey>Dubey J.P. 2010. Toxoplasmosis of animals and humans. 2nd ed, CRC Press. </ref>

In humans, it is one of the most common parasites. Blood test show that up to a third of the world population has been or is infected with T. gondii. Infection rates differ greatly from country to country.

Although mild, flu-like symptoms occasionally occur during the first few weeks, infection with T. gondii generally produces no symptoms in healthy human adults. But in infants, HIV/AIDS patients, and others with weakened immunity, infection can cause serious and occasionally fatal illness (toxoplasmosis).p77

Infection in humans and other warm-blooded animals can occur
 by eating raw or undercooked meat containing T. gondii tissue cysts.Tissue cyst = group of cells with a hard shell around them 
 by drinking water or eating anything contaminated with oocysts.Oocyst: a hardy, thick-walled spore able to survive for long periods outside a host. The zygote develops within the spore, which acts to protect it during transfer to new hosts. This method is found in some Apicomplexa. in the faeces of an infected animal.
 from a blood transfusion or organ transplant
 or by transmission from mother to foetus across the placenta.

The parasite can only sexually reproduce in the intestines of members of the cat family (felids). Felids are therefore the definitive hosts of T. gondii'', with all other hosts defined as 'intermediate hosts'.

 References 

Category:Apicomplexa
Category:Parasites