Effects of viral hemorrhagic fever inactivation methods on the performance of rapid diagnostic tests for Plasmodium falciparum.

Blood samples from patients with viral hemorrhagic fever (VHF) pose a serious risk to laboratory workers. Current contingency plans for VHF samples recommend the use of heat, gamma-irradiation, or Triton X-100 to inactivate samples before handling. Malaria is the most important alternative diagnosis to be excluded in cases of suspected VHF. Interpretation of malaria smears using samples inactivated with these methods is problematic because morphology is altered. The objective of this study was to assess the impact of different inactivation methods on the performance of rapid diagnostic tests for Plasmodium falciparum. Triton X-100 and gamma-irradiation of samples preserved detection. The impact of Triton X-100 inactivation was also "blindly" evaluated using 100 blood samples from febrile travelers. Triton X-100 inactivation of samples did not significantly affect the performance of these tests. This may represent a useful strategy for excluding the diagnosis of falciparum malaria in cases of suspected VHF.