Implementation of the global plan for insecticide resistance management in malaria vectors: progress, challenges and the way forward.

In recent years, there has been an increase in resistance of malaria vectors to insecticides, particularly to pyrethroids which are widely used in insecticide-treated nets. The Global Plan for Insecticide Resistance Management in malaria vectors (GPIRM), released in May 2012, is a collective strategy for the malaria community to tackle this challenge. This review outlines progress made to date and the challenges experienced in the implementation of GPIRM, and outlines focus areas requiring urgent attention.

The effect of dosing strategies on the therapeutic efficacy of artesunate-amodiaquine for uncomplicated malaria: a meta-analysis of individual patient data.

Background: Artesunate-amodiaquine (AS-AQ) is one of the most widely used artemisinin-based combination therapies (ACTs) to treat uncomplicated Plasmodium falciparum malaria in Africa. We investigated the impact of different dosing strategies on the efficacy of this combination for the treatment of falciparum malaria.

Methods: Individual patient data from AS-AQ clinical trials were pooled using the WorldWide Antimalarial Resistance Network (WWARN) standardised methodology.

Malaria vector control at a crossroads: public health entomology and the drive to elimination.

Vector control has been at the core of successful malaria control. However, a dearth of field-oriented vector biologists threatens to undermine global reductions in malaria burden. Skilled cadres are needed to manage insecticide resistance, to maintain coverage with current interventions, to develop new paradigms for tackling 'residual' transmission and to target interventions as transmission becomes increasingly heterogeneous.

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.

High prevalence of malaria in Zambezia, Mozambique: the protective effect of IRS versus increased risks due to pig-keeping and house construction.

Background: African countries are scaling up malaria interventions, especially insecticide treated nets (ITN) and indoor residual spraying (IRS), for which ambitious coverage targets have been set. In spite of these efforts infection prevalence remains high in many parts of the continent. This study investigated risk factors for malaria infection in children using three malaria indicator surveys from Zambezia province, Mozambique.

Longitudinal evaluation of Ocimum and other plants effects on the feeding behavioral response of mosquitoes (Diptera: Culicidae) in the field in Tanzania.

Background: The use of repellent materials from plants against nuisance insects is common with great potential to compliment existing malaria control programmes and this requires evaluation in the field. Ocimum plant species, Ocimum suave (Willd) and O. kilimandscharicum (Guerke) materials and their essential oils extracted by steam distillation were evaluated in the field and experimental huts for repellence, exophily and feeding inhibition effects against three mosquito species, Anopheles arabiensis (Patton), An.

Field evaluation of spatial repellency of metofluthrin-impregnated plastic strips against Anopheles gambiae complex in Bagamoyo, coastal Tanzania.

Metofluthrin is a newly synthesized pyrethroid possessing high knockdown and lethal activity against mosquitoes. Studies of metofluthrin-impregnated plastic strips have been performed with dengue vectors. This study reports the efficacy of the new prototypes of metofluthrin-impregnated plastic strips against malaria vectors, Anopheles gambiae complex, in the Kongo villages of Bagamoyo district in coastal Tanzania.

Ethnobotanical study of some of mosquito repellent plants in north-eastern Tanzania.

Background: The use of plant repellents against nuisance biting insects is common and its potential for malaria vector control requires evaluation in areas with different level of malaria endemicity. The essential oils of Ocimum suave and Ocimum kilimandscharicum were evaluated against malaria vectors in north-eastern Tanzania.

Methodology: An ethnobotanical study was conducted at Moshi in Kilimanjaro region north-eastern Tanzania, through interviews, to investigate the range of species of plants used as insect repellents.

Plasmodium falciparum genetic diversity in western Kenya highlands.

The present study examined the genetic diversity and population structure of Plasmodium falciparum in western Kenya by analyzing the polymorphism of 12 microsatellite loci and two antigen loci. Malaria in highland areas is unstable and epidemic whereas malaria in lowland areas is endemic. Transmission intensity and malaria prevalence are substantially lower in the highlands than in the lowlands.

Monitoring chloroquine resistance using Plasmodium falciparum parasites isolated from wild mosquitoes in Tanzania.

Monitoring antimalarial drug resistance is a useful epidemiologic tool and provides early detection of resistance foci. Using DNA extracted from the head/thorax of wild mosquitoes collected from Bagamoyo Coastal Tanzania, samples infected by Plasmodium falciparum (N = 89, in 2002 and N = 249 in 2004) were screened by nested polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay for mutations at Pfcrt76 and Pfmdr1-86 associated with chloroquine (CQ) resistance. The majority of isolates were of single infection (71%), and the prevalence of mutant alleles of Pfcrt76 decreased from 64.

Amplified fragment length polymorphism mapping of quantitative trait loci for malaria parasite susceptibility in the yellow fever mosquito Aedes aegypti.

The yellow fever mosquito Aedes aegypti has been the subject of extensive genetic research due to its medical importance and the ease with which it can be manipulated in the laboratory. A molecular genetic linkage map was constructed using 148 amplified fragment length polymorphism (AFLP) and six single-strand conformation polymorphism (SSCP) markers. Eighteen AFLP primer combinations were used to genotype two reciprocal F2 segregating populations.

Dynamics of gene introgression in the African malaria vector Anopheles gambiae.

Anopheles gambiae is a major malaria vector in Africa and a popular model species for a variety of ecological, evolutionary, and genetic studies on vector control. Genetic manipulation of mosquito vectorial capacity is a promising new weapon for the control of malaria. However, the release of exotic transgenic mosquitoes will bring in novel alleles in addition to the parasite-inhibiting genes, which may have unknown effects on the local population.

Microsatellite and mitochondrial genetic differentiation of Anopheles arabiensis (Diptera: Culicidae) from western Kenya, the Great Rift Valley, and coastal Kenya.

The population genetic structure of the African malaria vector Anopheles arabiensis from western Kenya, the Great Rift Valley, and coastal Kenya was investigated using 12 microsatellite loci and a partial sequence of mtDNA dehydrogenase gene subunit 5 (ND5). The mean number of alleles and the observed heterozygosity were similar for the mosquito populations from the three regions as revealed by the microsatellite data. A total of 30 polymorphic sites in the ND5 gene defined 39 haplotypes.

Microsatellite DNA polymorphism and heterozygosity in the malaria vector mosquito Anopheles funestus (Diptera: Culicidae) in east and southern Africa.

There has been an increase in malaria cases in southern African countries in recent years due to the presence of populations of Anopheles funestus that are resistant to the pyrethroid class of insecticides. Since A. funestus is one of the major African malaria vectors, knowledge of its genetic structure will benefit control strategies, such as the management of insecticide resistance, by allowing predictions to be made of possible spread of the resistance.

Species-specific primer for identification of Anopheles quadriannulatus sp. B (Diptera: Culicidae) from Ethiopia using a multiplex polymerase chain reaction assay.

Anopheles quadriannulatus Theobald historically has been reported from southern Africa, Zanzibar islands, and Ethiopia. However, based on evidences of genetic incompatibility between crosses of South African and Ethiopian populations, the population from Ethiopia was recently reported as a distinct species designated as An. quadriannulatus sp.