Knowledge and Perceptions on Malaria and Its Association with Aquatic Habitats

Background: Malaria remains the major cause of morbidity and mortality among children in Kenya. About 70 percent of the population is at risk of infection, and roughly 34,000 young children die of malaria-related causes annually.Objective: To investigate the knowledge and perceptions of the local people for malaria in relation to aquatic habitats along the Kenyan Lake Victoria basin.Design: Community-based cross-sectional study.Setting: The Kenyan Lake Victoria basin Region.Subjects: Two hundred and fourty three individuals (both women and men residing in the beaches and surrounding areas) were interviewed about their knowledge and perceptions regarding malaria.Results: Mosquitoes were perceived to be the main cause of malaria. Most respondents were familiar with the main signs and symptoms of mild malaria. Majority of the respondents had poor knowledge of mosquito breeding habitats with 45% mentioning the lake and only 18.6 and 8.9% mentioning ponds and dams, respectively. Most female respondents did not know the difference between mosquitoes and lake flies, P=0.03, Fishers exact test. The majority (97.5%) of the respondents reported seeking conventional malaria treatment from health institutions.Conclusion: Mosquitoes are perceived to be the main cause of malaria by both males and females. A significant proportion of the respondents were familiar with the main signs and symptoms of malaria and sought conventional medicine for treatment of the disease. Most of the respondents, however, had poor knowledge on the breeding habitats of mosquitoes. Concerted effort is needed to scale-up health education and improve the knowledge of the community about mosquitoes and their breeding habitats, particularly malaria vectors which do not breed in deep lake waters. Effective anti-malarial drugs should also be available at the grassroots level where the problem of malaria is rampant

The impact of permethrin-impregnated bednets on malaria vectors of the Kenyan coast.

The effects of introducing permethrin-impregnated bednets on local populations of the malaria vector mosquitoes Anopheles funestus and the An.gambiae complex was monitored during a randomized controlled trial at Kilifi on the Kenyan coast. Pyrethrum spray collections: inside 762 households were conducted between May 1994 and April 1995 after the introduction of bednets in half of the study area. All-night human bait collections were performed in two zones (one control and one intervention) for two nights each month during the same period. PCR identifications of An.gambiae sensu lato showed that proportions of sibling species were An.gambiae sensu stricto > An.merus > An.arabiensis. Indoor-resting densities of An.gambiae s.l. and the proportion of engorged females decreased significantly in intervention zones as compared to control zones. However, the human blood index and Plasmodium falciparum sporozoite rate remained unaffected. Also vector parous rates were unaltered by the intervention, implying that survival rates of malaria vectors were not affected. The human-biting density of An.gambiae s.l., the predominant vector, was consistently higher in the intervention zone compared to the control zone, but showed 8% reduction compared to pre-intervention biting rates-versus 94% increase in the control zone. Bioassay, susceptibility and high-performance liquid chromatography results all indicated that the permethrin content applied to the nets was sufficient to maintain high mortality of susceptible vectors throughout the trial. Increased rates of early outdoor-biting, as opposed to indoor-biting later during the night, were behavioural or vector composition changes associated with this intervention, which would require further monitoring during control programmes employing insecticide-treated bednets

Factors determining the occurrence of submicroscopic malaria infections and their relevance for control.

Malaria parasite prevalence in endemic populations is an essential indicator for monitoring the progress of malaria control, and has traditionally been assessed by microscopy. However, surveys increasingly use sensitive molecular methods that detect higher numbers of infected individuals, questioning our understanding of the true infection burden and resources required to reduce it. Here we analyse a series of data sets to characterize the distribution and epidemiological factors associated with low-density, submicroscopic infections. We show that submicroscopic parasite carriage is common in adults, in low-endemic settings and in chronic infections. We find a strong, non-linear relationship between microscopy and PCR prevalence in population surveys (n=106), and provide a tool to relate these measures. When transmission reaches very low levels, submicroscopic carriers are estimated to be the source of 20-50% of all human-to-mosquito transmissions. Our findings challenge the idea that individuals with little previous malaria exposure have insufficient immunity to control parasitaemia and suggest a role for molecular screening