Malaria In Nata Village, Northern Botswana: Evaluation Of Vector Control Methods

Abstract

The main aim of this study was three-fold: to determine villagers‟ knowledge about preferences for malaria control interventions; to investigate which mosquito species were prevalent in Nata village, and to determine whether the Plasmodium parasite that is carried by mosquitoes existed in Nata village from the sampled mosquitoes. Nata village is located in the Tutume malaria-endemic sub-district in Botswana. To meet the first aim of the study, interviewer-administered questionnaires which were completed by 109 volunteer participants. To address the second and third aims, Mosquito specimens were collected by using the H-trap and spray sheet collection methods. For the identification of mosquito species, morphological characteristics and molecular analysis techniques were used. Basic taxonomic keys (wings, abdomen, legs, and proboscis) were examined for morphological identification while the polymerase chain reaction (PCR) was mainly utilized for the molecular identification and detection of the Plasmodium parasite in the collected mosquito samples. A total of 109 participants consented to take part in the study. The majority (65%) of the participants were females and all the participants (100%) claimed to know about malaria control interventions. Only a small group (12%) of these study participants preferred the use of both long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) for sustained use and protection against malaria. Of the 27 mosquitoes used for the morphological analyses, 41% was identified as the Anopheles species while 59% was identified as Culex. Through PCR and the use of species specific primer, no Plasmodium parasites were detected in the DNA of any of the mosquitoes. It was thus established that the mosquitoes in the study area were not infected with the malaria parasite at the time of the study. However, the presence of the possible potential carriers of this parasite in this area suggests that the threat of malaria may still exist. For molecular identification of the mosquito sample, PCR was conducted with primers targeting CO1, 16S rRNA, and 18S rRNA. Only 16S rRNA was used for further analysis because no significant matches could be found on the NCBI database for CO1 and 18S rRNA sequences. Through phylogenetic analyses, three genera of mosquitoes, namely Anopheles, Aedes and Culex, were identified as prevalent in the study area. Seven mosquito species, including Culex quinquefasciatus, Culex pipiens quinquefasciatus, Culex coronator, Aedes aegypti, Aedes arborealis, Anopheles maculatus, and Anopheles eiseni were identified through phylogenetic analysis that revealed the existence of multiple mosquito species in Nata village. PCR analysis of the samples revealed the presence of vectors of diseases other than malaria. This investigation also elicited knowledge regarding the preferred methods of malaria control initiatives used by the community. This knowledge should be disseminated to support the implementation of environmentally safe malaria control tools and thereby improving the quality of life and health of humans in malaria-prone regions. This study revealed new findings about hitherto unsuspected species of mosquitoes that might co-exist with malaria carrier species or that might even influence malaria distribution in the study area. This is the first report that identified Aedes and Culex genera in Nata village or in the district where the village is situated, and the finding thus calls for further studies to determine the actual role played by these vectors in a malaria endemic area.