Insecticide susceptibility status of the malaria vector Anopheles arabiensis in Khartoum city, Sudan: differences between urban and periurban areas

Vector resistance to insecticides is becoming a major obstacle to malaria prevention measures. A baseline survey was carried out in Khartoum city, Sudan, during September-November 2007, to map the insecticide susceptibility status of Anopheles arabiensis and to examine the correlation with insecticide usage in urban agriculture. Susceptibility tests were conducted in 6 sentinel sites representing urban and periurban strata of the city. Mortality rates and knockdown times were calculated for 8 insecticides on a total of 9820 specimens. An. arabiensis was susceptible to bendiocarb [98.1%], propoxur [100%], fenitrothion [100%], deltamethrin [99.8%] and lambda-cyhalothrin [99.2%]. Susceptibility rates were significantly different between urban and periurban sites for malathion [80.8% vs 56.0%], DDT [99.0% vs 95.0%] and permethrin [98.5% vs 96.3%]. The 50% knockdown times were significantly higher in periurban than urban populations of An. arabiensis for deltamethrin, lambda-cyhalothrin and malathion

Dengue vector control and surveillance during a major outbreak in a coastal Red Sea area in Sudan

An unprecedented dengue outbreak occurred in 2010 in Port Sudan city, Sudan. Dengue incidence was 94 cases per 10 000 observed over 17 epidemiological weeks [total cases = 3 765]. We report here the impact of the vector control response plan to the outbreak, which mainly entailed house inspection and insecticide space spraying. In total 3 048 houses were inspected during vector surveillance and 19 794 larvae and 3 240 pupae of Aedes aegypti were collected. Entomological indices decreased during the period: house index declined from 100% to 16% [F= 57.8, P< 0.001] and pupal/person [P/P] index from 0.77 to 0.10 [F= 3.06, P< 0.01] in weeks 9 and 21 respectively. This decline was accompanied by a decrease in cases from a peak of 341 cases in week 13 to zero in week 29 and the end of the outbreak. There was a significant correlation between the entomological parameters and dengue incidence [R2 = 0.83, F= 23.9,P< 0.001]. Integrated epidemiological and vector surveillance is essential to an effective dengue control programme