Determination of malarial antibodies by means of screening and differentiating antigens.

4455 human sera with malarial antibodies were analysed with regard to their reactivity to screening antigens (Plasmodium fieldi and P. falciparum) and to differentiating antigens (P. vivax, P. ovale and P. malariae/brasilianum). Results were obtained by indirect fluorescent antibody test. The identification rate of antibodies was significantly higher with P. fieldi than with P. falciparum antigen, and was lowest for both of the screening antigens in sera with antibodies to P. ovale. The highest cross reactivity was between P. vivax and P. fieldi, the lowest between P. falciparum and P. fieldi. The majority of sera not reactive to screening antigens was reactive to P. ovale. The reactivity of sera to one of the screening antigens was higher in the group of immigrants from malaria endemic areas in comparison to European travellers, the overall pattern of results, however, was similar in both groups of patients.