Surveillance of Viral Haemorrhagic Fevers in Ghana: Entomological Assessment of the Risk of Transmission in the Northern Regions
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Date
2006-12
Journal Title
Journal ISSN
Volume Title
Publisher
Ghana Medical Journal
Abstract
Objectives: To assess the risk of transmission of
viral haemorrhagic fevers in northern Ghana.
Design: A two-year cross-sectional entomological
study was carried out in four communities in the
northern part of Ghana. Standard WHO methods
were used to collect adult and larvae of Aedes
mosquitoes to estimate man-vector contact rates
and larval indices.
Results: A total of 2804 households were surveyed
to estimate larval indices and man-vector
contacts of potential vectors of viral haemorrhagic
fevers such as Yellow fever and Dengue. Over
56% households in each study site were positive
for Aedes larvae. Relatively higher Breteaux index
(BI) and Container index (CI) were estimated in
Damongo (BI: 180 and CI: 44.8) and Jirapa (BI:
149.7 and CI: 41.5) compared to Tumu (BI: 76.1
and CI: 19.5) and Bolgatanga (BI: 72.4 and CI:
20.6). Man-biting rates of 9.8 and 18.5 bites
/man/hour were estimated for Damongo and Jirapa
respectively whilst Bolgatanga recorded 10
B/M/H. Generally, man-vector contact rates in all
the study sites were higher during the dry season
than the wet season. Larval indices showed seasonal
variations and the dry season was identified
as the high-risk period for transmission of viral
haemorrhagic fevers and possible disease outbreaks.
No flavivirus was detected in the 2034
Aedes mosquitoes from the study sites by RTPCR.
Conclusions: Aedes mosquito larval densities and
adult biting rates, in all the study areas were sufficient
to promote outbreaks of viral haemorrhagic
fevers.
Description
Journal Article
Keywords
Viral haemorrhagic fevers, Aedes, transmission, Ghana