ABSTRACT
Objective: To elucidate the larvicidal potency of neem, chinaberry and Bacillus thur-ingiensis israelensis (Bti) to larvae of Anopheles arabiensis under semi-field condition and adult susceptibility/resistance to the conventionally used insecticides in Tolay, Southwestern Ethiopia. Methods: Wild collected 3rd and 4th stage larvae were exposed to neem, and chinaberry seed powder dissolved in water and Bti in artificial containers at three treatment levels:0.2, 0.1 and 0.05 g/m2 and controls were free of treatments. Larval and pupal mortalities were monitored daily and residual activities were determined. The experiments were replicated three times. The World Health Organization tube test for all classes of in-secticides was conducted on adult Anopheles arabiensis reared from field collected larvae and pupae. Data were analyzed using STATA software version 11. Results: In the first application, neem powder caused 88.9%, 87.9%and 79.4%larval and pupal mortality at 0.2, 0.1 and 0.05 g/m2 after 4.3, 6.0 and 5.7 days, respectively. The cor-responding killing effect of chinaberry was 80.3%, 62.1%and 30.3%after 7.0, 7.7 and 8.3 days respectively. Bti at all treatments killed 100%after 24 h except 2.7 days for 0.05 g/m2. Adult mosquitoes were susceptible only for fenitrothion and pirimiphos-methyl with 100%mortality while resistant to deltamethrin, alpha-cypermethrin, etofenprox and dichloro-diphenyl-tricgloroethane with only 9.0%, 3.0%, 5.1%and 2.0%mortalities respectively. Conclusions: Neem, chinaberry and Bti showed potent larvicidal and pupicidal activ-ities. However, in the area, high level of mosquito resistance to pyrethroids and dichloro-diphenyl-tricgloroethane was seen which will pose serious challenge to vector control in the future. Therefore, using integrated approach including these botanical larvicides is warranted to manage insecticide resistance.
ABSTRACT
Background & objectives: Larval control is an integral part of malaria vector management in Ethiopia and elsewhere. For effective larval control, a sound understanding of the factors responsible for spatio-temporal variation in larval production is essential. A study was thus conducted to characterize larval habitats of anopheline mosquitoes in irrigation and major drainage areas between Adami Tulu and Meki towns, in the middle course of the Ethiopian Rift Valley. Methods: Aquatic habitats were sampled for anopheline larvae and the associated environmental variables (water temperature, turbidity, water current, water pH and other variables) were measured, characterized and analyzed. Results: Microscopic identification of the late instars (III and IV) of anopheline larvae collected throughout the study period yielded nearly 47.6% Anopheles pharoensis, 32.1% An. arabiensis, 17.1% An. squamosus and only 3.2% of other species (An. coustani and An. cinereus). Larvae of the local malaria vectors, An. arabiensis and An. pharoensis were most abundantly sampled from sand pools and natural swamps, respectively. Logistic regression analysis detected four best predictor variables associated with larval abundance of malaria vector species. Thus, relative abundance of An. arabiensis larvae was significantly and inversely associated with aquatic vegetation and water current, whereas the relative abundance of An. pharoensis larvae was significantly and positively associated with water temperature and the presence of algae in the water bodies. Conclusion: Dry season anopheline larval habitats such as riverine sand pools that are created and maintained by perennial water bodies and their associated water development projects need to be considered in vector control operations.
ABSTRACT
Background: Insecticide Treated Nets (ITNs) reduce malaria related mortality and morbidity significantly. Taking this into account; the Ethiopian Federal Ministry of Health has been distributing ITNs to malaria prone areas of the country through the support of the Global Fund. Objective: To study distributional coverage and assess the knowledge and utilization of insecticide treated nets in Ethiopia. Methods: A cross-sectional study was conducted in 17 malarious districts targeted for the first phase free distribution of long lasting insecticide treats nets (LLITNs) by the Ministry of Health in 9 administrative regions from October 2005 to September 2006. Region specific list of malarious districts where MOH distributed ITNs was used as the sampling frame for stratified random sampling of districts. One kebele (sub district) was selected from each of the selected districts using simple random sampling; and 15of the total households in the selected kebeles were selected using systematic random sampling. Upon obtaining informed consent from the household head or the oldest person in the household the questionnaire was administered and information was recorded. Data were double entered using EpiData version 3 and analyzed using SPSS version 12. Results: A total of 3131 households were visited; and 51.6of the respondents were males. The overall ITN distribution and utilization were 97.6and 81.6; respectively. The majority of households (53.2) owned a single net per family; highest in Dire Dawa (93.7) and lowest in Afar (17.6). Thirty eight percent of the respondents owned two nets per household. Most of the respondents (91.1) cited that ITNs are useful to control malaria either through prevention of mosquito bites (60) or prevention of the disease (39). Conclusion: ITN distribution; utilization; knowledge of users and its acceptability were good considering the recent introduction of the products. However; the person net ratio gap should be narrowed and emphasis needs to be given to vulnerable groups