Reference Values

Reference Range:  Pos = > 1:64    Neg  <1:64

     < 64 - Probably no recent clinical involvement with malaria

     => 64 - In U.S. citizens (brief exposure) may reflect recent infection; in some areas of the world, may be maximum titer demonstratable even in clinical cases.

In U.S. citizens with brief exposure to infection, a PLASMODIUM FALCIPARUM titer of =>1:64 may reflect recent infection. Speciation of the infecting malaria parasite is made by using four IFA slides prepared with P. FALCIPARUM, P. VIVAX, P. MALARIAE and P. OVALE, respectively. Antibody titers in U.S. citizens rarely persist more than six (6) months after chemotherapeutic cure. Titers in people with prolonged exposure and in people native to malaria endemic areas may persist for years because of relapses. Due to the increased volume of diagnostic specimens and to maximize the use of our malaria slides, we now titrate specimens at dilutions of 1:16 and 1:64. We will report immunofluorescence results that react at dilutions equal to or less than 1:16 as negative. Tests that react at dilutions of 1:64 will be reported as positive. By eliminating the reactivity of specimens at a dilution of 1:4 we are not changing the sensitivity of the immunofluorescence test.