Toxoplasma gondii infection in HIV-infected pregnant women: epidemiology and risks of mother-to-child transmission

Toxoplasma gondii (T. gondii) infects approximately one third of the world’s population. Globally there are an estimated 13.1 million cases of T. gondii co-infection in HIV-infected people with 87.1% of these individuals living in sub-Saharan Africa. The risk of T. gondii infection in HIV-infected women rises significantly with lower CD4+ T cell counts (particularly under 100 cells/μl). Mother-to-child transmission (MTCT) occurs in approximately 30% of cases of maternal T. gondii infection during pregnancy. The global prevalence of latent toxoplasmosis in HIV-infected pregnant women is 47.5% but the overall risk in HIV-infected mothers of MTCT of T. gondii is however, estimated to be low at < 5%. MTCT in HIV-infected mothers not only occurs due to T. gondii primary infection in pregnancy but also due to reactivation. Infants with congenital toxoplasmosis born to HIV-infected mother may have a more rapid onset and greater dissemination of disease thus having potentially devastating effects. This article discusses the key risks for MTCT of T. gondii infection in HIV-infected mothers as well highlighting the many knowledge gaps for which further study is required.