Effects of anticoagulants on Plasmodium vivax oocyst development in Anopheles albimanus mosquitoes.

Artificial membrane feeding (AMF) assays are used to determine malaria transmission-blocking activity in Anopheles. The purpose of this study was to determine the effect of the most widely used anticoagulants, EDTA and heparin, on development of the Plasmodium vivax sporogonic cycle. Blood samples collected from 60 patients carrying P. vivax infections were used to feed An. albimanus using AMF. Seven days after feeding, mosquitoes were dissected to assess mosquito infection. Mosquitoes fed with blood containing EDTA showed a lower mean oocyst number as compared with those fed blood with heparin. However, this effect was minimized upon reduction of EDTA concentrations in the serum. This result may be explained by the fact that microgametocytes require Ca(2+), Mn(2+), and Mg(+2) to activate enzymes important for exflagellation process and for motility of ookinetes. We therefore recommend that heparin be used as the anticoagulant of choice for blood used in AMF assays.