Insecticide resistance in malaria vectors in central Sudan
Date
2008-12-01T09:59:46Z
Authors
Abdalla, Hiba Mohammed Abu Bakr
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Abstract
Malaria is the leading cause of mortality and morbidity in Sudan. The annual malaria
cases and deaths are estimated at 7.5 million and 35, 000 respectively. One of the
possible factors that have led to this situation is the development of insecticide resistance
in the main malaria vector in Sudan, Anopheles arabiensis.
This study therefore, was initiated to identify the malaria vectors in Gezira and Sennar
states of central Sudan, determine their susceptibility levels to the different classes of
insecticides used for malaria vector control, identify mechanisms of resistance, and
determine the sporozoite infection rate and the blood meal sources in these populations.
The polymerase chain reaction (PCR) for species identification revealed that An.
arabiensis was the only member of the An. gambiae complex present in the study area.
The blood meal analysis using ELISA showed high anthropophily with 89.2% feeding on
humans. The overall sporozoite infection rate was 2.3 %. WHO susceptibility tests
showed complete susceptibility of An. arabiensis to bendiocarb (100% mortality) and
multiple resistance to permethrin (54-78%), DDT (55-66%) and malathion (76-78%).
The kdr mutation analysis revealed the presence of the West African kdr allele with the
majority of specimens being heterozygous (RS). The kdr in DDT/permethrin susceptible
specimens were: 15% homozygous for the kdr mutation (RR), 64.2% heterozygous (RS)
and 20.8% homozygous for the susceptible allele (SS). Amongst the DDT/permethrin
resistant specimens, 13% were SS, 48.7% RS and 38.3% RR. The apparent lack of correlation between kdr and resistant phenotype strongly suggests that other resistance
mechanisms are playing a role.
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Keywords
insecticide resistance, Anopheles arabiensis, kdr, Sudan