edoc

Malaria transmission after five years of vector control on Bioko Island, equatorial Guinea

Overgaard, H. J. and Reddy, V. P. and Abaga, S. and Matias, A. and Reddy, M. R. and Kulkarni, V. and Schwabe, C. and Segura, L. and Kleinschmidt, I. and Slotman, M. A.. (2012) Malaria transmission after five years of vector control on Bioko Island, equatorial Guinea. Parasites and Vectors, 5 (253).

[img]
Preview
PDF - Published Version
Available under License CC BY (Attribution).

1232Kb

Official URL: http://edoc.unibas.ch/dok/A6124688

Downloads: Statistics Overview

Abstract

BACKGROUND: Malaria is endemic with year-round transmission on Bioko Island. The Bioko Island Malaria Control Project (BIMCP) started in 2004 with the aim to reduce malaria transmission and to ultimately eliminate malaria. While the project has been successful in reducing overall malaria morbidity and mortality, foci of high malaria transmission still persist on the island. Results from the 2009 entomological collections are reported here.
METHODS: Human landing collections (HLC) and light trap collections (LTC) were carried out on Bioko Island, Equatorial Guinea in 2009. The HLCs were performed in three locations every second month and LTCs were carried out in 10 locations every second week. Molecular analyses were performed to identify species, detect sporozoites, and identify potential insecticide resistance alleles.
RESULTS: The entomological inoculation rates (EIR) on Bioko Island ranged from 163 to 840, with the outdoor EIRs reaching <900 infective mosquito bites per year. All three human landing collection sites on Bioko Island had an annual EIR exceeding the calculated African average of 121 infective bites per year. The highest recorded EIRs were in Punta Europa in northwestern Bioko Island with human biting rates of 92 and 66 mosquito landings per person per night, outdoors and indoors, respectively. Overall, the propensity for mosquito biting on the island was significantly higher outdoors than indoors (p>0.001). Both Anopheles gambiae s.s. and An. melas were responsible for malaria transmission on the island, but with different geographical distribution patterns. Sporozoite rates were the highest in An. gambiae s.s. populations ranging from 3.1% in Punta Europa and 5.7% in Riaba in the southeast. Only the L1014F (kdr-west) insecticide resistance mutation was detected on the island with frequencies ranging from 22-88% in An. gambiae s.s. No insecticide resistance alleles were detected in the An. melas populations.
CONCLUSIONS: In sp of five years of extensive malaria control and a generalized reduction in the force of transmission, parasite prevalence and child mortality, foci of very high transmission persist on Bioko Island, particularly in the northwestern Punta Europa area. This area is favorable for anopheline mosquito breeding; human biting rates are high, and the EIRs are among the highest ever recorded. Both vector species collected in the study have a propensity to bite outdoors more frequently than indoors. Despite current vector control efforts mosquito densities remain high in such foci of high malaria transmission. To further reduce transmission, indoor residual spraying (IRS) needs to be supplemented with additional vector control interventions.
Faculties and Departments:09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Department of Swiss Centre for International Health (SCIH) > Systems Performance and Monitoring (Pham-Tan)
UniBasel Contributors:Segura, Luis
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:BioMed Central
ISSN:1756-3305
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:16 Nov 2016 14:34
Deposited On:16 Aug 2013 07:28

Repository Staff Only: item control page