Toxoplasmosis: Toxoplasma gondii; Obligates intracellular parasites. 10-30% previous infected. Killed > 650C and < -120C 24 hours. Microwave not secure. Incubation 5-21 days. Comes ultimately from cats. Only 10% of infected women develop symptoms (glandular influenza/mononucleosis like symptoms) In most cases parasitiemia is less than 3 weeks. IgG antibodies increase 2-3 weeks after infection, if positive, IgM normally appear within the first week and generally decline within one month/months but may persist for years. Discuss with laboratory if in doubt. Risk of Fetus: Prevalence of congenital toxoplasmosis is 1-10 per 10.000 births. 30-50% gets infected. Transmission increases with gestational age. First the placenta is infected and later toxoplasmosis is transferred to the fetus. Transmission is possible in 1-15% in the first trimester resulting in 40% abortion or death and severe hydrocephalus and growth retardation. Second trimester: 30% are infected in the second trimester 10% being severely damaged. Third trimester: 60-90% are infected but only few percent are affected. The infection may be be latent and reactivated later (chorioretinitis, hearing loss and mental retardation). Symptoms and Sequelae: Symptoms: 1/3 lymphfadenit, 1/3 tired and only ¼ seeks edical help without the diagnosis has been established. Less than 10% have symptoms as newborns (The classic triade: hydrocephalus, intra-cranial calcification, chorioretinitis, and most have fever, jaundice thrombocytopenia, hepatosplenomegaly). These cases have high mortality and morbidity with mental retardation and blindness. Mild and subclinical infection will give sequelae (minimal brain damage) and 1/3 will later need special help in school. Diagnosis: Negative IgG/IgM not infected previously, but repeat after 10-14 days if mother has been subjected to infection. IgM > 300 iu/ml suggest active infection. Positive IgM up to 6-8 months, but can persist for years. IGM-positives should always undergo confirmatory tests in a reference atory. IgA suggest infection. If negative IgG and positive IgM repeat after 2 weeks if unchanged possible unspecified activity. IgM combined with increased IgG suggest a recent infection (3 weeks apart). High IgAG avidity rule out infection acquired in the recent 3-4 months. Low IgG avid test indicate recent infection, but can persist beyond 3 months after infection. Amniocentesis with PCR analyses the best method for detecting fetal infection (four weeks after infection), probably less reliable before 18 14 weeks. Current practice is to advice all women to have amniocentesis (unless infection is acquired late in pregnancy), and to suggest termination only if there is a diagnosis of fetal infection and detection of abnormalities in ultrasound. Start treatment if IgA or IgM are positive. If PCR negative in NS blood, negative IgM and IgA the infant is possibly not infected, but test again after 3, 6, 9 and 12 months. Ultrasound: Ventriculomegaly most common, cerebral calcification (Most often normal neuro- developmental outcome if seen alone), hepatomegaly, hyperechoic foci within the liver, pericardial or pleural effusion/ ascites/hydrops placenta megaly Treatment: Spiromycin (Rovamycin 1 x 3) (does not cross the placenta well) 1 g x 3 until the diagnosis has been confirmed and the rest of the pregnancy This caused 60% reduction in transmission rate. Some stop treatment with Spiramycin if confirmatory tests show no fetal infection. If infected: 3 weeks course with Spiramycin and then 3 weeks with Pyremetacin and Sulfodiazins All infected children should be treated for one year. Leucovorin (folic acide) (10-25 g/day/PO) to prevent bone marrow suppression. Re-infection can occur but does not seem to result in congenital transmission. Prevention: Do not eat undercooked or raw meat (swine and lamb) Avoid contact with cat excrements. Wash or peeling fruits and vegetables. Maintaining good kitchen hygiene and hand washing. Use gloves when gardening. References: (1) UpToDate 2005, Online 13.3 (2) Dunn D, et al. Mother-to-child transmission of toxoplasmosis: risk estimates for clinical counseling. Lancet 1999; 353(9167):1829-33. (3) Montoya JG, Liesenfeld o. Toxoplasmosis. Lancet 2004; 363(9425):1965-76.
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