Congenital Infection with Toxoplasma gondii: A Case Control Study in Tehran, Iran

The prevalence of antibodies in Toxoplasma gondii ranges from 24 to 57.7% in Iran. Children who acquire T. gondii in intrauterine period are at increased risk of sequels and need prolonged treatment. The aim of the study is to compare serum specific T. gondiiantibodies (IgM and IgG ELISA) between infants suspected to have intrauterine infections (< 1year) and control infants. This case control study was done in the pediatrics department of Rasul hospital in Tehran (2007 to 2008). We compared specific T. gondii antibodies (IgM and IgG) in serum by ELISA in 50 infants (< 1year) suspected to have intrauterine infections based on diagnostic criteria for intrauterine infections (WHO-TORCH) and 30 healthy controls. Mean age in these cases was 4.7 + 3.7 months; and in the controls was 5.3 + 3.1 months. Acute T. gondii infection (IgM) was detected in 10% (5/51) of the cases, but none (0/30) in the controls; while previous immunity for T. gondii (IgG) was found in 18% (9/50) of the cases and 60% (18/30) of the controls. Although the rate of acute infection was higher in the cases but was not significant (P-value = 0.09), previous immunity (IgG) was significantly higher in the control’s healthy group (P-value = 0.00). However, T. gondii infection (IgM) was confirmed in at least 10% of the cases. As such, we prefer to consider seropositive (T. gondii - IgM) infants (clinically for intrauterine infection) in congenital form, by adding the symptomatic cases with negative IgM and IgG (PCR studies are needed for R/o of intra uterine infection). Probably, T. gondii infection is at least the 2nd common cause of intrauterine infection in studied infants with serology (<1 year old), like cases with hearing loss (after CMV). Post natal screening program (serology) may be beneficial for rapid diagnosis, but negative symptomatic cases should be followed up by the PCR study. We recommend prevention and treatment of T. gondii in pregnant women for prevention of congenital toxoplasmosis. At least, 1 year treatment is needed in infants (positive IgM) for prevention of its sequels.   Key words: Toxoplasma gondii, congenital toxoplasmosis, ELISA (enzyme-linked immunosorbent assay), intrauterine infection, TORCH (Toxoplasma gondii, Rubella, Cytomegalovirus, Herpes).