The population structure of Anopheles gambiae in Africa was studied using 11 microsatellite loci in 16 samples from 10 countries. All loci are located outside polymorphic inversions. Heterogeneity among loci was detected and two putative outlier loci were removed from analyses aimed at capturing genome-wide patterns. Two main divisions of the gene pool were separated by high differentiation (F(ST) > 0.1). The northwestern (NW) division included populations from Senegal, Ghana, Nigeria, Cameroon, Gabon, Democratic Republic of Congo (DRC), and western Kenya. The southeastern (SE) division included populations from eastern Kenya, Tanzania, Malawi, and Zambia. Inhospitable environments for A. gambiae along the Rift Valley partly separate these divisions. Reduced genetic diversity in the SE division and results of an analysis based on private alleles support the hypothesis that a recent bottleneck, followed by colonization from the NW populations shaped this structure. In the NW division, populations possessing the M rDNA genotype appeared to form a monophyletic clade. Although genetic distance increased with geographic distance, discontinuities were suggested between certain sets of populations. The absence of heterozygotes between sympatric M and S populations in the DRC and the high differentiation in locus 678 (F(ST)>0.28) contrasted with low differentiation in all other loci (-0.02
SummaryPopulation coverage of insecticide-treated nets (ITNs) in Africa falls well below the Abuja target of 60% while coverage levels achieved during vaccination campaigns in the same populations typically exceed 90%. Household (HH) cost of ITNs is an important barrier to their uptake. We investigated the coverage, equity and cost of linking distribution of free ITNs to a measles vaccination campaign. During a national measles vaccination campaign in Zambia, children in four rural districts were given a free ITN when they received their measles vaccination. In one urban district, children were given a voucher, which could be redeemed for a net at a commercial distribution site. About 1700 HHs were asked whether they received vaccination and an ITN during a measles campaign, as well as questions on assets (e.g. type roofing material or bicycle ownership) to assess HH wealth. Net ownership was calculated for children in each wealth quintile. In the rural areas, ITN coverage among children rose from 16.7% to 81.1% and the equity ratio from 0.32 to 0.88 and in the urban area from 50.7% to 76.2% (equity ratio: 0.66-1.19). The operational cost per ITN delivered was $0.35 in the rural area with direct distribution and $1.89 in the urban areas with voucher distribution. Mass distribution of ITNs through vaccination campaigns achieves rapid, high and equitable coverage at low cost.
With its 2006-2011 National Malaria Strategic Plan, Zambia committed to control malaria at a national scale. This scale-up for impact approach was facilitated by sound business planning and financing in 2006 of approximately US$35 million. Compared with surveys in 2001 and 2004, a 2006 national survey of 14,681 persons in 2,999 households at the end of the transmission season showed substantial coverage increases for preventive interventions. Ownership and use rates of insecticide-treated mosquito nets (ITNs) among vulnerable groups doubled, with 44% of households owning ITNs and 23% of children less than five years of age and 24% of pregnant women using them. Roll Back Malaria Abuja targets for intermittent preventive treatment in pregnancy (IPTp) were exceeded, with 62% of pregnant women receiving at least two doses of IPTp. As of 2006, Zambia is demonstrating substantial progress toward the national targets (80% population coverage rates for the interventions) and aspires to show that malaria need not be its leading health problem, and that malaria control is a sound national investment.
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