Anti-malarial contact dependent blocking of transmission of Plasmodium vivax by Anopheles darlingi mosquito vector.

Malaria, caused by protozoa of the genus Plasmodium and transmitted to humans through the bite of mosquitoes of the genus Anopheles, remains a public health problem. Long-Lasting Insecticide -treated Bed Nets (LLINS) and Indoor Residual Spraying (IRS) represent the main vector control measures for malaria prevention. However, to address the concerns of mosquito resistance to pyrethroids, other malaria control strategies are being explored for effectively blocking malaria transmission by eliminating or reducing the parasite in the vector. This study evaluated the use of antimalarials through tarsal contact of female Anopheles darlingi infected with Plasmodium vivax via a Direct Membrane Feeding Assay (DMFA). Female An. darlingi were exposed tarsally using Petri dishes impregnated with antimalarials at 1 mmol/m2 for exposure times of 6 or 60 minutes. Among the antimalarials evaluated were Atovaquone (ATQ), Tafenoquine (TQ), Chloroquine (CQ), Mefloquine (MQ), Primaquine (PQ), and the compound Nanchangmycin (NCG). Atovaquone was the only antimalarial evaluated before and after DMFA at exposure times of 60 min and 6 min. The results demonstrate complete elimination of P. vivax in female An. darlingi exposed to ATQ by tarsal contact 60 min before infection. ATQ was also effective 6 min before or after infection, reducing infection prevalence. In addition, MQ also significantly reduced infection intensity, but there was no difference in infection prevalence. No significant differences were observed for the other antimalarials.