Parasitology
Toxoplasmosis
· A protozoa/parasite
·
Main source: cysts in meat. Also
kitten faeces (eg cyst in garden – pregnant gardeners should wear gloves)
·
Presentation:
o Immunocompetent:
§ Lymphadenopathy (eg unilateral)
§ Maybe: fever, myalgia, acute pharyngitis, hepatosplenomegaly, atypical
mononucleosis
§ Usually self-limiting – may take months to settle
§ If persistent/recurrent lymphadenopathy ® ?Need
for treatment
o Immunodeficient:
§ Acquired or reactivated
§ AIDS most common: CNS involvement (solitary space occupying lesion, encephalitis),
also myocarditis, hepatitis
§ Less common in transplants and encephalitis
o Ocular toxoplasmosis: most cases in adolescents and adults ® reactivation infection. ® Blurred vision, photophobia, multiple retinal lesions
o Congential Toxoplasmosis:
§ 29% fetal infection if mother has primary CMV infection
§ Highest risk in 3rd trimester (1st trimester may miscarry)
§ Complications: spontaneous abortion, premature, still birth
§ Surviving neonates: bilateral choroido-retinitis. In severe cases, TORCH type symptoms
·
Lab diagnosis:
o PCR test for toxoplasmosis: amniotic fluid, CSF (AIDS patients)
o Lymph node biopsy ® characteristic histology
o Serology:
§ IgM antibody after 5 – 14 days, peaks at 2 – 4 weeks, traces for up to a
year
§ IgG: high levels for up to 6 months, declines slowly over years
§ Avidity test: can differentiate between acute phase „immature‟ IgG and
„mature‟ IgG
· Treatment:
o Pyrimethamine (Gold standard, but gives bone marrow suppression + give
folate) + sulphadiazine (not available in NZ)
o Pyrimethamine + clindamycin (gives C. difficile diarrhoea)
·
Spiramycin (only one safe in
pregnancy)
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