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Toxoplasmosis - Cat and Dog (view source)
Revision as of 20:30, 12 August 2010
, 20:30, 12 August 2010→Transmission
===Transmission===
===Transmission===
Any of the three life stages of T gondii can infect warmblooded
vertebrates, including cats and humans. Since
tachyzoites are readily inactivated by gastric secretions,
most orally acquired infections develop following the
ingestion of bradyzoites or sporozoites. Coprophagy is
uncommon in cats; the usual source of infection is the
ingestion of T gondii bradyzoites during carnivorous
feeding. Oocysts can generally be detected in the faeces
from three days post-infection (see graph on the right)
and oocyst shedding is usually completed by 10 to 21
days post-infection. Only 20 per cent of cats infected by
ingestion of sporulated oocysts will shed the organism;
the onset of oocyst shedding is between 18 and 44 days
post-infection, and the patent period is six to 10 days
(Dubey and Lappin 1998).
Transplacental infection occurs if a T gondii-naive
woman or queen ingests T gondii during gestation. First
trimester infections are rare but, when they occur, the
sequelae are generally severe. In humans, stillbirth, abortion
and severe CNS disease are common. In neonatally
infected kittens, interstitial pneumonia, necrotising
hepatitis, myocarditis, non-suppurative encephalitis and
uveitis are commonly detected after necropsy and histological
examination. In humans, the fetus is more likely
to be infected if exposed during the second and third
trimesters but the resultant disease is usually milder. The
same may be true for cats. Previously infected women or
queens are unlikely to transmit T gondii to the fetus,
even if exposed during gestation.
==Signalment==
==Signalment==