Assessing Anopheles vector species diversity and transmission of malaria in four health districts along the borders of Côte d’Ivoire
Date
2021
Journal Title
Journal ISSN
Volume Title
Publisher
BMC Malar
Abstract
Background: Although malaria and Anopheles mosquito vectors are highly prevalent in Côte d’Ivoire, limited data
are available to help understand the malaria vector density and transmission dynamics in areas bordering the country.
To address this gap, the Anopheles mosquito species diversity, the members of the Anopheles gambiae complex and
the transmission of malaria were assessed in four health districts along the borders of Côte d’Ivoire.
Methods: From July 2016 through December 2016 and July 2017 through December 2017, adult Anopheles mosquitoes
were collected in four health districts of Côte d’Ivoire (Aboisso, Bloléquin, Odienné and Ouangolodougou)
using standardized window exit trap (WET) and pyrethrum knockdown spray collection (PSC) methods. The collected
mosquitoes were identified morphologically at species level and the members of the An. gambiae complex were
separated using short interspersed nuclear element-based polymerase chain reaction (SINE-PCR). Anopheles gambiae
sensu lato (s.l.), Anopheles funestus s.l. and Anopheles nili specimens were analysed for malaria Plasmodium parasite
detection using the cytochrome oxidase I gene (COX-I), and malaria prevalence among human population through
local Ministry of Health (MoH) statistical yearbooks.
Results: A total of 281 female Anopheles were collected in Aboisso, 754 in Bloléquin, 1319 in Odienné and 2443 in
Ouangolodougou. Seven Anopheles species were recorded including An. gambiae s.l. (94.8–99.1%) as the main vector,
followed by An. funestus s.l. (0.4–4.3%) and An. nili (0–0.7%). Among An. gambiae s.l., Anopheles coluzzii represented the
predominant species in Aboisso (89.2%) and Bloléquin (92.2%), while An. gambiae sensu stricto (s.s.) was the major
species in Odienné (96.0%) and Ouangolodougou (94.2%). The Plasmodium sporozoite infection rate in An. gambiae
s.l. was highest in Odienné (11.0%; n = 100) followed by Bloléquin (7.8%, n = 115), Aboisso (3.1%; n = 65) and Ouangologoudou
(2.5%; n = 120). In An. funestus s.l., Plasmodium falciparum sporozoite infection rate was estimated at 6.2%
(n = 32) in Bloléquin, 8.7% (n = 23) in Odienné. No An. funestus s.l. specimens were found infected with P. falciparum
sporozoite infection in Ouangolodougou and Aboisso. No P. falciparum sporozoite was detected in An. nili specimens
in the four health districts. Among the local human populations, malaria incidence was higher in Odienné (39.7%;
n = 45,376) and Bloléquin (37.6%; n = 150,205) compared to that in Ouangolodougou (18.3%; n = 131,629) and
Aboisso (19.7%; n = 364,585).
Conclusion: Anopheles vector species diversity, abundance and Plasmodium sporozoite infection were high within
the health districts along the borders of the country of Côte d’Ivoire, resulting in high malaria transmission among the
local populations. Anopheles gambiae s.l. and An. funestus s.l. were found to be highly infected with Plasmodium in the
health districts of Bloléquin and Odienné where higher malaria incidence was observed than the other districts. This
study provides important information that can be used to guide Côte d’Ivoire National Malaria Control Programme for
vector control decision-making, mainly in districts that are at the country borders.
Description
Research Article
Keywords
Côte d’Ivoire, Anopheles, malaria, vector species, Plasmodium, Border health district