Examining the human infectious reservoir for Plasmodium falciparum malaria in areas of differing transmission intensity.

A detailed understanding of the human infectious reservoir is essential for improving malaria transmission-reducing interventions. Here we report a multi-regional assessment of population-wide malaria transmission potential based on 1209 mosquito feeding assays in endemic areas of Burkina Faso and Kenya. Across both sites, we identified 39 infectious individuals. In high endemicity settings, infectious individuals were identifiable by research-grade microscopy (92.6%; 25/27), whilst one of three infectious individuals in the lowest endemicity setting was detected by molecular techniques alone. The percentages of infected mosquitoes in the different surveys ranged from 0.05 (4/7716) to 1.6% (121/7749), and correlate positively with transmission intensity. We also estimated exposure to malaria vectors through genetic matching of blood from 1094 wild-caught bloodfed mosquitoes with that of humans resident in the same houses. Although adults transmitted fewer parasites to mosquitoes than children, they received more mosquito bites, thus balancing their contribution to the infectious reservoir

Malaria hotspots defined by clinical malaria, asymptomatic carriage, PCR and vector numbers in a low transmission area on the Kenyan Coast

Background Targeted malaria control interventions are expected to be cost-effective. Clinical, parasitological and serological markers of malaria transmission have been used to detect malaria transmission hotspots, but few studies have examined the relationship between the different potential markers in low transmission areas. The present study reports on the relationships between clinical, parasitological, serological and entomological markers of malaria transmission in an area of low transmission intensity in Coastal Kenya. Methods Longitudinal data collected from 831 children aged 5–17 months, cross-sectional survey data from 800 older children and adults, and entomological survey data collected in Ganze on the Kenyan Coast were used in the present study. The spatial scan statistic test used to detect malaria transmission hotspots was based on incidence of clinical malaria episodes, prevalence of asymptomatic asexual parasites carriage detected by microscopy and polymerase chain reaction (PCR), seroprevalence of antibodies to two Plasmodium falciparum merozoite antigens (AMA1 and MSP1-19) and densities of Anopheles mosquitoes in CDC light-trap catches. Results There was considerable overlapping of hotspots by these different markers, but only weak to moderate correlation between parasitological and serological markers. PCR prevalence and seroprevalence of antibodies to AMA1 or MSP1-19 appeared to be more sensitive markers of hotspots at very low transmission intensity. Conclusion These findings may support the choice of either serology or PCR as markers in the detection of malaria transmission hotspots for targeted interventions

Parametric Subtypes in ABEL

Several problems arise when parametric subtypes are used in ABEL. This paper deals with subtype parameters, the disjointness relation and the generation of prole sets, extended to handle type parameters properly. I show how more type-information can be obtained syntactically by studying the proles of the parametric type generators. 1 Introduction For an introduction to ABEL (Abstraction Building Experimental Language), refer to [DO91] and a more recent paper [DO95]. 1.1 Types and Subtypes Each type T in ABEL has an associated attribute V T , where V T is the value set of T . There are two kinds of subtypes in ABEL; syntactic and semantic ones. Syntactic subtypes and the main type itself are dened simultaneously. Example 1 type Int by Neg,Zero,Pos with NPos = Neg+Zero and Nat = Pos+Zero and Nzro = Neg+Pos == module func 0 : \Gamma! Zero - - zero func S : Nat \Gamma! Pos - - successor func N : Pos \Gamma! Neg - - negation one-one genbas 0,S ,N - - generator basis endm..