Human malaria: standardization of serologic tests for individual diagnostic and seroepidemiologic surveys

Abstract

The indirect immunofluorescence antibody test (IFA) is normally employed as reference test in the serology of malaria. In this report we standardized and optimized the test, for our condition, utilizing P. falciparum obtained from human blood on culture and P. vivax obtained from human blood as antigens, for detection of IgG and IgM antibodies. Some technical variables, were tested and best resulto were obtained when sera were diluted in PBS containing 1% Tween-80 and the slides, containing the antigenic preparation were fixed in cold acetone or stabilized on dried air with silica. The ELISA test was standardized for P. falciparum antibodies and the comparison of the IFA and ELISA showed: a) in P. falciparum prime infected patient the sensitivity was 71% for both tests; b) in P. vivax prime infected patients the sensitivity was 40% for both tests; c) in non prime infected patients with P. falciparum malaria the sensitivity was 100% for both tests; d) in non prime infected patients with P. vivax malaria the sensitivity was 85% for ELISA and 92% for IFA; e) in patients with P. vivax and P. falciparum malaria the sensitivity was 100% for both tests. The specificity was 95% for ELISA and 100% for IFA in non malaria individuals. The results showed that the ELISA test could be an alternative for IFA for IgG antibodies in the serology of malaria.