30 terms

Veterinary Science: Parasitology-Small Animals-Toxoplasma gondii

What organism causes toxoplasmosis?
Toxoplasma gondii
What type of organism is Toxoplasma gondii
What two sites of replication exit?
Intestinal and Extraintestinal
What species is the DH of Toxoplasma gondii?
What species are paratenic hosts?
mice, sheep, poultry
What is the PPP of Toxoplasma gondii?
2-3 days for sporulation
What are the routes of infection?
Direct (faecal oral), Parantenic Host (cats eating mice)
How can humans contract Toxoplasma gondii?
Mostly by eating raw or undercooked meat from paratenic hosts (eg sheep) or injestion of sporulated oocysts directly from faecal contaimination of vegetbles.
What are the names given to sporozoites in the tissue?
Bradyzoites, Tachyzoites
Explain tachyozoites replicaton?
Fast, asexual
Explain bradyozoties replication?
Slow, encapsulated as cysts in tissue for life
How long will cats shed oocysts in faeces?
10-20 days only during the intestinal phase
What is 'premunition'?
occurs due to the presence of Bradyzoites in extra-intestinal stages
What are CSx of Toxoplasma gondii in the intestinal phase in cats?
mild, self-limiting diarrhoea
What is the Pathogenesis of Toxoplasma gondii in the Extra-intestinal phase in cats dogs and humans?
rapid multiplication of tachyzoites which cause destructon of cells, pyrexia, mulit-systemic disorders including neurological, hepatic, gastrointestinal, respiratory, occular depending upon where the site of tachyzoite division occurs
Is toxoplasmosis in dogs primary or secondary infection?
Secondary due to other disease/drugs causing immunosuppression
In a dog ,1 year of age, what commonly casues young dog to be immunocompromised?
Distemper, Tx with cyclosporin
What is the basis of Dx for Toxoplasma gondii?
vaccination Hx, medical Hx, Serology (high IgM titres=acute infection), increased paired IgG titires), T.gondii antibodies in CSF, tachyzoites detected by PCR or cytology, CBC and biochem changes consistent with organ-specific diease, Response to treatment.
What is the aim for Tx for Toxoplasma gondii?
Suppress tachyzoite replication
What Tx drug?
Clindamycin, Trimethoprim-Sulphonamide pyrimethamine, Azithromycin
Response to Tx
Clinical improvement in 24-48 hours, unless permanent damage of organ due to necrosis
Is Toxoplasma gondii a zoonoses?
What % of human pop has +ve antibodies?
What symptons do humans present?
mild flu-like, fever, sore throat, weakness
How might an acutes infection of toxoplasmosis occur in humans?
drinking infected water (chorioretinitis)
What humans are predisposed to toxoplasmosis?
immunocompromised, AIDS, organ transplant, women who contract Toxoplasma gondii for the first time whilst they are pregnant and get vertical transmission
If 33% of women have antibodies to toxoplasmosis), do they risk abortion or foetal abnormalities (hydrocephalis)?
No. usually only get these if woman has not had infection prior to first pregnancy. Life-long immunity confered.
If the likelyhood of transmission to the foetus is high in the 3rd trimester, what are the symptoms?
Mild, asymptomatic, chorioretinitis
Do pregnant women usually contract Toxoplasma gondii from cats?
no. usually get from raw or under-cooked meat from paratenic hosts like sheep. Cats only shed oocyts for 1-2 weeks. If woman has cat and is hygenic and throws cat litter out everyday (with gloves) no infection as sporulation takes 2-3 days in faeces.
What prevention measures should a pregnant or HIV suffer undertake?
Cook meat thoroughly, wash / cook raw foods thoroughly, Do not allow cat to hunt (keep indoors), Do not feed raw meat, Clean litter tray DAILY wearing gloves, Hygiene, wash hands, Avoid gardening, Oocysts can survive for up to 1.5 years in soil