Potential factors influencing lymphatic filariasis transmission in “hotspot” and “control” areas in Ghana: the importance of vectors
Date
2019
Authors
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Journal ISSN
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Publisher
BMC
Abstract
Background: Mass drug administration (MDA) programmes for the control of lymphatic filariasis in Ghana, have
been ongoing in some endemic districts for 16 years. The current study aimed to assess factors that govern the
success of MDA programmes for breaking transmission of lymphatic filariasis in Ghana.
Methods: The study was undertaken in two “hotspot” districts (Ahanta West and Kassena Nankana West) and two
control districts (Mpohor and Bongo) in Ghana. Mosquitoes were collected and identified using morphological and
molecular tools. A proportion of the cibarial armatures of each species was examined. Dissections were performed
on Anopheles gambiae for filarial worm detection. A questionnaire was administered to obtain information on MDA
compliance and vector control activities. Data were compared between districts to determine factors that might
explain persistent transmission of lymphatic filariasis.
Results: High numbers of mosquitoes were sampled in Ahanta West district compared to Mpohor district (F = 16.
09, P = 0.002). There was no significant difference between the numbers of mosquitoes collected in Kassena
Nankana West and Bongo districts (F = 2.16, P = 0.185). Mansonia species were predominant in Ahanta West district.
An. coluzzii mosquitoes were prevalent in all districts. An. melas with infected and infective filarial worms was found
only in Ahanta West district. No differences were found in cibarial teeth numbers and shape for mosquito species
in the surveyed districts. Reported MDA coverage was high in all districts. The average use of bednet and indoor
residual spraying was 82.4 and 66.2%, respectively. There was high compliance in the five preceding MDA rounds in
Ahanta West and Kassena Nankana West districts, both considered hotspots of lymphatic filariasis transmission.
Conclusions: The study on persistent transmission of lymphatic filariasis in the two areas in Ghana present
information that shows the importance of local understanding of factors affecting control and elimination of
lymphatic filariasis. Unlike Kassena Nankana West district where transmission dynamics could be explained by initial
infection prevalence and low vector densities, ongoing lymphatic filariasis transmission in Ahanta West district
might be explained by high biting rates of An. gambiae and initial infection prevalence, coupled with high densities
of An. melas and Mansonia vector species that have low or no teeth and exhibiting limitation
Description
Research Article
Keywords
Lymphatic filariasis, Microfilariae, Vector control