[Detection of IgA antibodies as important markers of acute primary infection with Toxoplasma gondii]

Abstract

The diagnosis of Toxoplasma gondii infection is currently based on immunological tests, but tests for IgM and IgG antibodies alone are often insufficient to estimate the risk of active disease, especially during pregnancy and in immunodeficient patients. Classically the study of anti-toxoplasma immunity involves titration of IgG antibodies, which reflect immunity to the parasite, and IgM antibodies which of present, reveal acute infection. However, technical advances have shown the limitations of these tests as tests for IgM can be positive because of residual specific IgM or even in subjects free of acute infection due to the existence of natural interfering IgM. In addition, IgM can be absent in children with congenital toxoplasmosis or subjects with secondary reactivation. The purpose of our study was to evaluated of IgA antibodies to T. gondii in serum samples which were positive in screening test. Our results confirm the diagnostic value of testing for anti-toxoplasma IgA antibodies. These antibodies are absent in uninfected subjects and are detected rapidly after primary infection. The determination of IgA complements IgM determination for the diagnosis of toxoplasmosis.