Serological rebound in congenital toxoplasmosis: long-term follow-up of 133 children

Although serological rebound is common in infants with congenital toxoplasmosis, clinical recommendations for management, in particular the need for additional treatment, vary. The goals of our retrospective cohort study in 133 consecutive children with congenital toxoplasmosis were to estimate the incidence and duration of the rebounds, identify predictive factors, assess the long-term risk of eye lesions and the need for treatment. We first estimated the incidence and duration of rebounds and identified predictive factors using an univariate analysis and a Cox model modified to include time-dependent variables. Two cohort studies were then conducted to compare the incidence density of secondary eye lesions in children who had a rebound versus no rebound, and among children who had a rebound after initial therapy, in those who received an additional course of treatment and in those who did not. Of the 133 children, 93 (70%) had at least one rebound during a mean follow-up of 95 months. Of those with one rebound diagnosed after initial treatment, 33 received an additional 3-month course of pyrimethamine/sulphadoxine and 48 were not treated. Intracranial calcification at birth was associated with an increased relative risk (RR) of rebound (RR=2.601; P=0.03), and treatment with pyrimethamine/sulphadoxine between 2 and 12 months of age with a decreased risk (RR=0.3; P=0.0845), whereas age of pregnancy at maternal infection, type of treatment during pregnancy and sex were not found to be predictive factors. There was no difference in incidence densities of secondary eye lesions in children without rebound (7/3,367 child-months) compared to those with at least one rebound (22/9,609 child-months) (RR=1.10; 95% CI: 0.47–2.58), and, among the 81 children who had one rebound diagnosed after initial treatment, in those who received an additional course of treatment and in those who did not (RR=0.72; 95% CI: 0.30–1.72). Conclusion: serological rebound is common in children with congenital toxoplasmosis but, due to the risk and constraints, an additional course of treatment and more ophthalmological surveillance than currently practiced do not seem warranted.