A rapid assessment approach for public health decision-making related to the prevention of malaria during pregnancy

Objective: To develop a rapid field assessment methodology to address the burden of malaria during pregnancy and the options for intervening within the existing antenatal care system in Kenya. Methods: Surveys consisting of questionnaires, sampling of blood for parasitaemia and anaemia, and birth outcome assessment were conducted in antenatal clinics, delivery units, and in the community in Ksumu and Mombasa, Kenya. Findings: T he ratges of maternal anaemia and severe anaemia, were, resctively, 79 cent and 8 cent in Kisumu, and 95 cent and 24 cent in Mombasa. The rates of placental parasitaemia were 27 cent and 24 cent and the ratges of low birth weight were 18 cent and 24 cent in Kisumu and Mombasa, respectively. Women with placental parasitaemia had a higher incidence of low birth wight compared with women without placental parasitaemai in both Kisumu (28 cent vs 16 cent,P=0.0004) and Mombasa (42 cent vs 20 cent, P=0.004). A total of 95 cent and 98 cent for women in Kisumu and Mombasa, respectively, reported attending an antenatal clinic during their previous pregnancy. Conclusion: This metodology can be used by ministries of health to collect data for decision-making regarding malaria control during pregnancy: it can also privide a baseline measurement on which to evaluate subsequent interventions

Polymorphism in the gene encoding the Pfs48/45 antigen of Plasmodium falciparum. XI. Asembo Bay Cohort Project.

We have investigated the genetic diversity of the gene encoding the transmission-blocking vaccine antigen Pfs48/45 of Plasmodium falciparum parasites from western Kenya and compared it with parasite populations from Thailand, India, and Venezuela. We report 44 complete new sequences. Overall, the antigen is less polymorphic as compared with other pre-erythrocytic and blood stage antigens. Contrary to other P. falciparum antigens, the number of synonymous substitutions per synonymous site exceeds the number of non-synonymous substitutions per non-synonymous site. We have found that the Pfs48/45 gene of Kenyan parasites is more polymorphic than parasites from other geographic origins. Our analysis reveals that positive natural selection is involved in the maintenance of the observed polymorphism. No evidence of intragenic recombination was found. F(st) values reveal high levels of gene flow between India and Thailand, however, there are strong constraints in gene flow among Kenyan, Southeast Asian, and Venezuelan parasites. No alleles could be linked to a specific geographic region. The results of this study suggest that this gametocyte antigen, like other asexual blood stage antigens, is under selection pressure.