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A Snap Shot of the Prevalence of Anopheles Merus and its Role in Malaria Transmission in Pemba

London School of Hygiene & Tropical Medicine, L. (2008) A Snap Shot of the Prevalence of Anopheles Merus and its Role in Malaria Transmission in Pemba. UNSPECIFIED. (Unpublished)

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Abstract

Malaria is a serious public health problem in Pemba. It is holoendemic and thus affects mostly children and pregnant women. Following intense vector control activities in recent years, there has been a notable decline in malaria cases, presumably due to reduced populations of An. gambiae s.s. However, it was noted by Wastling (2007) that some areas in Pemba were supporting large populations of An. merus, a vector which the ZMCP recorded as absent in 2005 (ZMCP, 2007). It is probable that changes to vector population previously observed following vector control activities of the 1960’s may be taking place. To ensure the continued effectiveness of the Pemban malaria vector control campaign, it is prudent to determine the relative proportion of An. merus (and other members of An. gambiae s.l.) in Pemba; to document where the larvae and adults are found and consider its potential impact in the transmission of Plasmodium and the implications for clinical malaria in the region. Larvae were sampled from a diverse range of water habitats (41 sites) and ecological features of each larval site were recorded in order to investigate their relationship to species distribution and relative abundance. CDC light traps were used to collect host seeking mosquitoes from households and a goat shed neighbouring suspected An. merus breeding sites. A PCR assay was used to identify the specimens collected. Ribosomal DNA (rDNA) analysis was performed on a total of 216 larvae from 19 populations. 120 larvae were positively assigned to 3 species: An. merus (50%), An. arabiensis (5%) and An. quadrannulatus (1%). Whilst 96 larvae (44%) remained unidentified. Of the 5 mosquitoes collected 2 were identified as An. merus and 3 were unidentified. An. merus dominated in brackish-waters, showing great plasticity in its choice of larval habitat. However its relative abundance decreased at high altitudes. The species composition of the An. gambiae complex appears to be undergoing the same changes as observed during the spraying campaigns of the 1950s and 60s. The occurrence of endophilic members of the An. gambiae complex have reduced significantly whilst the exophilic members; (mostly) An. merus, An. arabiensis and An. quadriannulatus thrive. However the role of this species in malaria transmission cannot be commented upon due to limited sampling results.

Item Type: Other
Keywords: Malaria, Public Health, Vector Control, Plasmodium, Mosquitoes, Anopheles Merus, Pemba
Subjects: Malaria > Vector control
Divisions: Other
Depositing User: Mr Joseph Madata
Date Deposited: 04 Apr 2013 09:31
Last Modified: 04 Apr 2013 09:31
URI: http://ihi.eprints.org/id/eprint/1271

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