Novel genetic polymorphisms associated with severe malaria and under selective pressure in North-eastern Tanzania.

Significant selection pressure has been exerted on the genomes of human populations exposed to Plasmodium falciparum infection, resulting in the acquisition of mechanisms of resistance against severe malarial disease. Many host genetic factors, including sickle cell trait, have been associated with reduced risk of developing severe malaria, but do not account for all of the observed phenotypic variation. Identification of novel inherited risk factors relies upon high-resolution genome-wide association studies (GWAS).

Interceptor® long-lasting insecticidal net: phase III evaluation over three years of household use and calibration with Phase II experimental hut outcomes.

Background: Long-lasting insecticidal nets (LN) are an effective tool for malaria prevention. The World Health Organization Pesticide Evaluation Scheme has established evaluation criteria to facilitate registration for public use. A household randomised trial was conducted in Tanzania according to WHOPES Phase III procedures to evaluate the alpha-cypermethrin coated Interceptor® LN (BASF) over three years' use.

Evaluation of ICON Maxx, a long-lasting treatment kit for mosquito nets: experimental hut trials against anopheline mosquitoes in Tanzania.

Background: Insecticide-treated nets are the primary method of preventing malaria. To remain effective, the pyrethroid insecticide must withstand multiple washes over the lifetime of the net. ICON(®) Maxx is a 'dip-it-yourself' kit for long-lasting treatment of polyester nets.

USP38, FREM3, SDC1, DDC, and LOC727982 Gene Polymorphisms and Differential Susceptibility to Severe Malaria in Tanzania.

Populations exposed to Plasmodium falciparum infection develop genetic mechanisms of protection against severe malarial disease. Despite decades of genetic epidemiological research, the sickle cell trait (HbAS) sickle cell polymorphism, ABO blood group, and other hemoglobinopathies remain the few major determinants in severe malaria to be replicated across different African populations and study designs. Within a case-control study in a region of high transmission in Tanzania (n = 983), we investigated the role of 40 new loci identified in recent genome-wide studies.

African glucose-6-phosphate dehydrogenase alleles associated with protection from severe malaria in heterozygous females in Tanzania.

X-linked Glucose-6-phosphate dehydrogenase (G6PD) A- deficiency is prevalent in sub-Saharan Africa populations, and has been associated with protection from severe malaria. Whether females and/or males are protected by G6PD deficiency is uncertain, due in part to G6PD and malaria phenotypic complexity and misclassification. Almost all large association studies have genotyped a limited number of G6PD SNPs (e.

Is housing quality associated with malaria incidence among young children and mosquito vector numbers? Evidence from Korogwe, Tanzania.

Background: Several studies conducted in Northeast Tanzania have documented declines in malaria transmission even before interventions were scaled up. One explanation for these reductions may be the changes in socio-environmental conditions associated with economic development, and in particular improvements in housing construction.

Objective: This analysis seeks to identify (1) risk factors for malaria incidence among young children and (2) household and environmental factors associated with mosquito vector numbers collected in the child's sleeping area.

Evaluation of the long-lasting insecticidal net Interceptor LN: laboratory and experimental hut studies against anopheline and culicine mosquitoes in northeastern Tanzania.

Background: Long lasting insecticidal nets (LN) are a primary method of malaria prevention. Before new types of LN are approved they need to meet quality and efficacy standards set by the WHO Pesticide Evaluation Scheme. The process of evaluation has three phases.

Candidate human genetic polymorphisms and severe malaria in a Tanzanian population.

Human genetic background strongly influences susceptibility to malaria infection and progression to severe disease and death. Classical genetic studies identified haemoglobinopathies and erythrocyte-associated polymorphisms, as protective against severe disease. High throughput genotyping by mass spectrometry allows multiple single nucleotide polymorphisms (SNPs) to be examined simultaneously.

Pyrethroid resistance in Anopheles gambiae, in Bomi County, Liberia, compromises malaria vector control.

Background: Long Lasting Insecticidal Nets (LLIN) and Indoor Residual Spraying (IRS) have both proven to be effective malaria vector control strategies in Africa and the new technology of insecticide treated durable wall lining (DL) is being evaluated. Sustaining these interventions at high coverage levels is logistically challenging and, furthermore, the increase in insecticide resistance in African malaria vectors may reduce the efficacy of these chemical based interventions. Monitoring of vector populations and evaluation of the efficacy of insecticide based control approaches should be integral components of malaria control programmes.

Identification of hot spots of malaria transmission for targeted malaria control.

Background: Variation in the risk of malaria within populations is a frequently described but poorly understood phenomenon. This heterogeneity creates opportunities for targeted interventions but only if hot spots of malaria transmission can be easily identified.

Methods: We determined spatial patterns in malaria transmission in a district in northeastern Tanzania, using malaria incidence data from a cohort study involving infants and household-level mosquito sampling data.

Evaluation of PermaNet 3.0 a deltamethrin-PBO combination net against Anopheles gambiae and pyrethroid resistant Culex quinquefasciatus mosquitoes: an experimental hut trial in Tanzania.

Background: Combination mosquito nets incorporating two unrelated insecticides or insecticide plus synergist are designed to control insecticide resistant mosquitoes. PermaNet 3.0 is a long-lasting combination net incorporating deltamethrin on the side panels and a mixture of deltamethrin and synergist piperonyl butoxide (PBO) on the top panel.

Equity and coverage of insecticide-treated bed nets in an area of intense transmission of Plasmodium falciparum in Tanzania.

Background: There is no clear consensus on the most sustainable and effective distribution strategy for insecticide treated bed nets (ITNs). Tanzania has been a leader in social marketing but it is still not clear if this can result in high and equitable levels of coverage.

Methods: A cluster-randomized survey of ITN and bed net ownership and use was conducted in a rural area exposed to intense Plasmodium falciparum transmission in NE Tanzania where ITN distribution had been subject to routine delivery of national strategies and episodic free distribution through local clinics.

An experimental hut evaluation of Olyset nets against anopheline mosquitoes after seven years use in Tanzanian villages.

Background: Long-lasting insecticidal nets (LLINs) are advocated by WHO for protection against malaria. Of the three brands of LLINs currently approved by WHO, Olyset(R) is the only one currently granted full recommendation. With this type of LLIN, the insecticide (permethrin) is incorporated into the polyethylene fibre during manufacture and diffuses from the core to the surface, thereby maintaining surface concentrations.

Efficacy of pyrethroid-treated nets against malaria vectors and nuisance-biting mosquitoes in Tanzania in areas with long-term insecticide-treated net use.

Objective: To measure pyrethroid susceptibility in populations of malaria vectors and nuisance-biting mosquitoes in Tanzania and to test the biological efficacy of current insecticide formulations used for net treatment.

Methods: Anopheles gambiae Giles s.l.

Integrating HIV testing into immunological studies of non-HIV-related diseases.

HIV testing is now required for non-HIV-AIDS-related immunological studies in areas of high HIV prevalence. Ethical guidelines for testing in these circumstances need clarification and sensitive protocols need to be developed.

Measuring the efficacy of insecticide treated bednets: the use of DNA fingerprinting to increase the accuracy of personal protection estimates in Tanzania.

Summary Insecticide-treated nets have proved successful in the prevention of malaria as a result of both the personal protection with which they provide the sleeper and also the 'mass effect' on the local mosquito population when they are used on a community-wide basis. Personal protection estimates are normally based on comparisons of the numbers of bloodfed mosquitoes found in rooms with and without nets, however it seemed possible that a number of those mosquitoes may not have fed on the occupants of the rooms in which they were found but had entered after feeding elsewhere. To address this possible source of error, we used an 8-locus microsatellite system to identify the source of bloodmeals of Anopheles gambiaes.

Variation of malaria transmission and morbidity with altitude in Tanzania and with introduction of alphacypermethrin treated nets.

Background: Highland areas with naturally less intense malaria transmission may provide models of how lowland areas might become if transmission was permanently reduced by sustained vector control. It has been argued that vector control should not be attempted in areas of intense transmission.

Methods: Mosquitoes were sampled with light traps, pyrethrum spray and window exit traps.

Scaling-up coverage with insecticide-treated nets against malaria in Africa: who should pay?

Insecticide-treated nets (ITNs) have been shown to reduce the burden of malaria in African villages by providing personal protection and, if coverage of a community is comprehensive, by reducing the infective mosquito population. We do not accept the view that scaling-up this method should be by making villagers pay for nets and insecticide, with subsidies limited so as not to discourage the private sector. We consider that ITNs should be viewed as a public good, like vaccines, and should be provided via the public sector with generous assistance from donors.