Mopti and savanna molecular forms of the malaria vector anopheles Gambiae S.S populations from Bugiri and Iganga south–eastern Uganda

Abstract

Female anopheles mosquitoes transmit malaria in humans and other mammals; Anopheles gambiae sensu stricto which is the primary vector of Plasmodium falciparum has been classified into two molecular forms, Savanna and Mopti. It had previously been suggested that there exist differences between these two forms in both insecticide resistance traits and susceptibility to P. falciparum. This study aimed at establishing the distribution of malaria vector species and molecular forms of An. gambiae s.s populations in Iganga and Bugiri districts south-eastern Uganda. Such entomological studies contribute to knowledge required by vector control programs and implementation of other public health intervention programs such as the use of indoor Residue spraying and insecticide treated nets. To this end, mosquitoes were collected between November and December 2010 using indoor pyrethrum spray collection from two villages of both Iganga and Bugiri districts. Morphological identification of species was done as previously described and mosquito species and molecular forms of An. gambiae s.s were done using PCR. A total of 665 samples were analysed. Out of 284 mosquitoes collected from Bugiri, 222 samples (78.1%) were An. arabiensis, 43 (15.1%) An. funestus, 12(4.2%) An. gambiae s.s and less than 5% unidentified. In Iganga, of the 381 mosquitoes identified with PCR, 200 (52.5%) were An. gambiae s.s, 123(32.2%) An. funestus, 49(12.9%) were An. arabiensis and the rest were unidentified. A total of 212 An. gambiae s.s identified were characterised further into molecular forms and all were identified as savanna molecular form. No Mopti or hybrid patterns of An. gambiae s.s were detected. Savanna molecular form of An. gambiae s.s is the only molecular form found in South Eastern Uganda. More extensive studies should be done to detect new evolving species in Uganda and other molecular identification assays developed using different sites apart from rDNA.

Female anopheles mosquitoes transmit malaria in humans and other mammals; Anopheles gambiae sensu stricto which is the primary vector of Plasmodium falciparum has been classified into two molecular forms, Savanna and Mopti. It had previously been suggested that there exist differences between these two forms in both insecticide resistance traits and susceptibility to P. falciparum. This study aimed at establishing the distribution of malaria vector species and molecular forms of An. gambiae s.s populations in Iganga and Bugiri districts south-eastern Uganda. Such entomological studies contribute to knowledge required by vector control programs and implementation of other public health intervention programs such as the use of indoor Residue spraying and insecticide treated nets. To this end, mosquitoes were collected between November and December 2010 using indoor pyrethrum spray collection from two villages of both Iganga and Bugiri districts. Morphological identification of species was done as previously described and mosquito species and molecular forms of An. gambiae s.s were done using PCR. A total of 665 samples were analysed. Out of 284 mosquitoes collected from Bugiri, 222 samples (78.1%) were An. arabiensis, 43 (15.1%) An. funestus, 12(4.2%) An. gambiae s.s and less than 5% unidentified. In Iganga, of the 381 mosquitoes identified with PCR, 200 (52.5%) were An. gambiae s.s, 123(32.2%) An. funestus, 49(12.9%) were An. arabiensis and the rest were unidentified. A total of 212 An. gambiae s.s identified were characterised further into molecular forms and all were identified as savanna molecular form. No Mopti or hybrid patterns of An. gambiae s.s were detected. Savanna molecular form of An. gambiae s.s is the only molecular form found in South Eastern Uganda. More extensive studies should be done to detect new evolving species in Uganda and other molecular identification assays developed using different sites apart from rDNA.