Experimental Study: The Relationship between Plasmodium falciparum Gametocyte Carriage and Mosquitoes Infectiousness in Two Sympatric Ethnic Groups in Burkina Faso

Aims: The lower susceptibility of the Fulani to malaria compared to Mossi was previously described in Burkina Faso in West Africa. The mature gametocyte stage of Plasmodium falciparum is known to be the only stage capable of infecting the mosquito though this process is disrupted by the action of immunity and other factors as well. Our study aims to assess the ability of two sympatric ethnic groups known to have different susceptibility to Plasmodium falciparum malaria, to infect mosquitoes through an experimental membrane feeding assay.

Methodology: Study participants were gametocyte carriers aged from 2 to 12 years recruited in the village of Barkoundouba where Fulani and Mossi are living in sympatric. A venous blood was obtained from each participant for direct membrane feeding assay of insectary reared mosquitoes. Blood fed mosquitoes were stored for 7 days with sugar water as the only food source, then dissected for the microscopic detection for oocysts.

Results: A total of 1050 mosquitoes were used for the experimental infections. Eight day after feeding, a total of 897 mosquitoes were dissected, 275 from the Fulani and 622 from the Mossi group. With an average of 43 stomachs examined by experimentation, the mosquito infestation rate was 10.5% in Fulani and 13.2% in Mossi group (p=0.569). The fed mosquito rate was 95 % and 95.6% in Fulani and Mossi ethnic group respectively (p=0.241). The rate of survival mosquitoes after the feeding was 96.5% and 87.5% in Fulani and Mossi ethnic group respectively (p=0.088). The proportion of dissected mosquitoes was 100% and 99.2% in Fulani and Mossi ethnic group respectively (p=0.138) leading to an average oocystic load of 249 in Fulani and 21 in Mossi group. The success rate of DMFA in both groups combined was 57.14%. Indeed, this rate was 33.33% and 66.67% in Fulani and Mossi group respectively.

Conclusion: Our study showed that there is no significant difference found between the two ethnic group with the fed, survival, dissected and the infested mosquitoes rate. However, the average of oocystic load was higher in Fulani than the Mossi group despite the low infection in Fulani group. There is a need to explore the mechanism underlying such difference between the two ethnic groups.