Malaria Transmission around the Memve’ele Hydroelectric Dam in South Cameroon: A Combined Retrospective and Prospective Study, 2000–2016

Abstract

Dam constructions are considered a great concern for public health. The current study aimed to investigate malaria transmission in the Nyabessan village around the Memve'ele dam in South Cameroon. Adult mosquitoes were captured by human landing catches in Nyabessan before and during dam construction in 2000-2006 and 2014-2016 respectively, as well as in the Olama village, which was selected as a control. Malaria vectors were morphologically identified and analyzed for <i>Plasmodium falciparum</i> circumsporozoite protein detection and molecular identification of <i>Anopheles (A.) gambiae</i> species. Overall, ten malaria vector species were identified among 12,189 <i>Anopheles</i> specimens from Nyabessan (<i>N</i> = 6127) and Olama (<i>N</i> = 6062), including <i>A. gambiae</i> Giles (1902), <i>A. coluzzii</i> Coetzee (2013), <i>A. moucheti</i> Evans (1925), <i>A. ovengensis</i> Awono (2004), <i>A. nili</i> Theobald (1903), <i>A. paludis</i> Theobald (1900), <i>A. zieanni</i>, <i>A. marshallii</i> Theobald (1903), <i>A. coustani</i> Laveran (1900), and <i>A. obscurus</i> Grünberg (1905). In Nyabessan, <i>A. moucheti</i> and <i>A. ovengensis</i> were the main vector species before dam construction (16-50 bites/person/night-b/p/n, 0.26-0.71 infective bites/person/night-ib/p/n) that experienced a reduction of their role in disease transmission in 2016 (3-35 b/p/n, 0-0.5 ib/p/n) (<i>p</i> < 0.005). By contrast, the role of <i>A. gambiae s.l.</i> and <i>A. paludis</i> increased (11-38 b/p/n, 0.75-1.2 ib/p/n) (<i>p</i> < 0.01). In Olama, <i>A. moucheti</i> remained the main malaria vector species throughout the study period (<i>p</i> = 0.5). These findings highlight the need for a strong vector-borne disease surveillance and control system around the Memve'ele dam.