Entomological Studies on the Species Composition and the Significance of Insecticide Treated Mosquito Nets (ITNs) Against Malaria Vector in Guragie Zone, Southern Ethiopia
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Date
2007-07
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Addis Ababa University
Abstract
Studies on species composition and significance of Insecticide Treated
mosquito Nets (ITNs) for malaria vector control were conducted in four
randomly selected localities in Jolie Peasant Association, Meskan Woreda,
Guragie Zone, Southern Ethiopia. Larval and adult collections were
carried out, from different sites throughout the study period to identify
species composition, thus three Anopheline species: Anopheles gambiae
s.l., Anopheles pharoensis and Anopheles christyi were identified. An.
gambiae s.l. was the principal vector responsible for the transmission of
malaria in the study area. The main identified breeding sites in the study
area includes rain pools, river pockets, ponds, marshes and pools of
water from spillage of canals which are the result of human activities
rather than environmental causes.
To investigate the effect of Insecticide (Permethrin) Treated Mosquito Nets
(ITNs), 20 houses with and without ITNs were paired. Malaria incidence,
resting density and parity rate were assessed. The result of malaria
incidence showed that the difference was not significant at (2 = 0.6247,
P > 0.05). However, a clear reduction in the density of indoor resting
population of An. gambiae s.l. were found in houses with ITNs (t =
10.0278, df = 38, p < 0.05). Similarly, the parous rates were significant
at (2 = 4.657, p < 0.05).
Further entomological studies are required to determine the vectorial
status of the Anophelines in this area. Besides, in providing an enabling
environment for scaling-up actions, governmental sectors need to focus
on creating awareness on utilization and demand for ITNs through health
information channels and mass media. At the end of 2004, 107 countries and territories had areas at risk of
malaria transmission. Some 3.2 billion people lived in areas at risk of
malaria transmission. An estimated 350–500 million clinical malaria
episodes occur annually; most of these are caused by infection with P.
falciparum and P. vivax. Malaria causes more than 1 million deaths each
year, out of which 90% of the malaria cases and deaths occur in Africa. It
also contributes indirectly too many additional deaths, mainly in young
children, through synergy with other infections and illnesses (World
Malaria Report, 2005; TDR, 1997-98).
In Africa, Southeast Asia and Eastern Mediterranean region estimated
number of deaths due to malaria in 2002 indicates that, 89% (1,136,000),
5.1% (65,000), and 4.6% (59,000), respectively. Malaria control in Africa
is less successful because of the occurrence of drug resistant parasites
and insecticide resistant vectors, changes in the resting behavior of
mosquito (from endophily to exophily) as the result of frequent indoor
insecticide sprays, lack of efficient infrastructure, shortage of trained
man power, lack of equipment, financial constraints, lack of appropriate
management and inability to integrate several method of control (World
Malaria Report, 2005; Toure, 1999).
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Biology