Is a positive IgM antibody harmful for the fetus?
Q: I am pregnant and I got my toxoplasmosis IgM and IgG titres tested in the 9th week of gestation. The results were negative for IgG but positive for IgM (48.7). This test was done using Elisa. What should I do now? Do I have to terminate my pregnancy? If not, then is there any suspection for passing of the disease to the fetus? Will there be any abnormalities in the fetus? Will this parasite affect my health? Do I need some medication for it? Can I get rid of this parasite forever? I don't know, when I got infected with this. Do I need other confirming tests?
A:The IgM antibody indicates recent infection and IgG antibody past infection. Your IgM antibody titre is slightly higher than normal (positive). I advise you to get the test repeated immediately. Irrespective of whether it is positive (low positive) or high positive or negative, I would advice you to repeat it 3rd time from same laboratory (where 2nd testing was done) after 2 weeks. At that time the lab should test the sample drawn on the 2nd occasion along with the sample drawn the 3rd time as well (to rule out any inter test error). Further management will depend upon these results. If the 2nd and 3rd samples were negative, You need not worry and have your ultrasound done regularly by an experienced sonologist. If the tests are positive (even if low positive), I would advise you to have the pregnancy terminated. Chances of the baby getting infected are 15%, 30% and 60% (approximately) if acute infection in mother occurs in the 1st, 2nd or 3rd trimester respectively. One trimester is of 3 months. It is no point putting yourself to complications of cordocentesis (drawing of blood from umbilical cord) and testing it for evidence of infection of baby. Besides, it is a specialized procedure and very few gynaecologists are competent to perform this test. Another test is amniotic fluid for PCR of toxoplasma or isolation of toxoplasma. Very few research centres have these facilities. The chances of fetal wastage - abortion, death of fetus (baby) and severe neurological complications (including hydrocephaly, microcephaly) in the baby are highest when infection occurs in 1st trimester and lowest or mild neurological problems, or subclinical infection when infection of baby occurs in 3rd trimester. Even if tests show that baby is not infected, the baby must be examined well and followed up to childhood to make sure no problems due to congenital infection have occurred. You are fortunate that acute infection is detected in 1 1st trimester. If repeated testing shows acute infection, I strongly advocate termination of pregnancy. You can then (for documentation sake) get the aborted fetus sent for toxoplasma isolation. However, that would just be a theoretical exercise. Drugs are available - spiramycin (which decrease chance of congenital infection) and pyrimethamine-sulphadiazine combination. However, the last 2 drugs are not given before 14 weeks of pregnancy due to their harmful effects on developing baby. However, before attempting the next pregnancy, you should be treated with these drugs and ensure the IgG levels have come down.