Life Cycle Two host pattern with alternation of generations----mammal <>mammal ToXoplasma gondi is a serious zoonotic parasite that has almost all the warm blooded animals as the reservior hosts(intermediate hosts Life cycle includes two phases called the intestinal (or enteroepithelial)and extraintestinal phases
• Two host pattern with alternation of generations----mammal → mammal • Toxoplasma gondii is a serious zoonotic parasite that has almost all the warm blooded animals as the reservior hosts (intermediate hosts) • Life cycle includes two phases called the intestinal (or enteroepithelial) and extraintestinal phases Life Cycle
Life Cycle The intestinal phase occurs in cats only and produces oocysts hosts Schizogony -schizont >merozoite asexual reproduction Gametogony -male female gamete fertilize oocyst sexual reproduction Sporogony -sporocyst >sporozoites asexual reproduction The extraintestinal phase occurs in all infected animals(including cats)and produces trophozoites -asexual reproduction hosts) Tachyzoites-pseudocysts Bradyzoites --cysts
• The intestinal phase occurs in cats only and produces "oocysts" (___ hosts) – Schizogony – schizont →merozoite asexual reproduction – Gametogony – male & female gamete fertilize → oocyst sexual reproduction – Sporogony – sporocyst →sporozoites asexual reproduction • The extraintestinal phase occurs in all infected animals (including cats) and produces trophozoites -- asexual reproduction (__ hosts) – Tachyzoites – pseudocysts – Bradyzoites -- cysts Life Cycle
Life Cycle ToXoplasmosis can be transmitted by ingestion of oocysts(in cat feces)or pseudocysts"or"cysts"(in raw or undercooked meat) Shedding of oocysts in faeces is most common in kittens but can occur in any age of cat Oocysts can remain infectious for several months and are quite resistant to disinfectants drying and freezing Tissue cysts are less resistant, and are destroyed by proper cooking of food
• Toxoplasmosis can be transmitted by ingestion of oocysts (in cat feces) or “pseudocysts" or “cysts"(in raw or undercooked meat) • Shedding of oocysts in faeces is most common in kittens, but can occur in any age of cat • Oocysts can remain infectious for several months and are quite resistant to disinfectants, drying and freezing. Tissue cysts are less resistant, and are destroyed by proper cooking of food Life Cycle
Pathogenesis >In general, most of the human population infected With Toxoplasma are asymptomatic carriers >There are a number of factors which determine whether an infected host will express disease symptoms The strain of the pathogen(RH strain) -The susceptibility of the host --immunocompromised -Age of the host -new born infants Degree of acquired immunity
Pathogenesis ➢In general, most of the human population infected with Toxoplasma are asymptomatic carriers ➢There are a number of factors which determine whether an infected host will express disease symptoms –The strain of the pathogen (RH strain) –The susceptibility of the host -- immunocompromised –Age of the host – new born infants –Degree of acquired immunity
Pathogenesis The tachyzoites directly destroy host cells
Pathogenesis The tachyzoites directly destroy host cells