Bio-efficacy and wash resistance of MAGNet long-lasting insecticidal net against wild populations of Anopheles funestus in experimental huts in Muheza, Tanzania

Abstract

Background The decline in malaria cases and vectors is major milestone in fighting against malaria. The efficacy of MAGNet long-lasting insecticidal nets (MAGNet LLIN), an alpha-cypermethrin incorporated long-lasting net, with the target dose ± 25% of 5.8 g active ingredient (AI)/kg (4.35–7.25 g AI/kg) was evaluated in six veranda-trap experimental huts in Muheza, Tanzania against freely flying wild population of Anopheles funestus. Methods MAGNet LLINs were tested against wild, free-flying, host-seeking An. funestus mosquitoes over a period of 6 weeks (total of 36 nights in the huts). MAGNet LLIN efficacy was determined in terms of mosquito mortality, blood-feeding inhibition, deterrence, induced exiting, personal protection, and insecticidal killing over 20 washes according to WHO standardized procedures. Efficacy was compared with reference to a WHOPES recommended approved LLINs (DuraNet) and to a net conventionally treated (CTN) treated with alpha-cypermethrin at WHO-recommended dose and washed to just before cut-off point. The efficacy of MAGNet was evaluated in experimental huts against wild, free-flying, pyrethroid-resistant An. funestus. The WHO-susceptibility method was used to detect resistance in wild Anopheles exposed to 0.75% permethrin. Mosquito mortality, blood-feeding inhibition and personal protection were compared between untreated nets and standard LLINs. Blood-feeding rates were recorded and compared between the 20 times washed; blood-feeding rates between 20 times washed MAGNet LLIN and 20 times washed WHOPES-approved piperonyl butoxide (PBO)/pyrethroid were not statistically different (p > 0.05). Results The results have evidently shown that MAGNet LLIN provides similar blood-feeding inhibition, exophily, mortality, and deterrence to the standard approved LLIN, thus meeting the WHOPES criteria for blood feeding. The significantly high feeding inhibition and personal protection over pyrethroid-resistant An. funestus recorded by both unwashed and 20 times washed MAGNet compared to the unwashed DuraNet, the WHOPES-approved standard pyrethroid-only LLIN provides proof of MAGNet meeting Phase II WHOPES criteria for a LLIN. Conclusion Based on this study, MAGNet has been shown to have a promising impact on protection when 20 times washed against a highly resistant population of An. funestus.

Impact of Plasmodium falciparum pfhrp2 and pfhrp3 gene deletions on malaria control worldwide: a systematic review and meta-analysis

“…As a consequence, this review provides an original global and complete overview of the current situation of these gene deletions. Two previous systematic reviews had partially targeted pfhrp2 and pfhrp3 gene deletions in a specific context (Africa and India) [ 64 , 65 ], but not worldwide, and a further review was more focused on methodological aspects; however, fewer articles have been included [ 66 ].…”

“…Finally, the reliability of results from sample-based studies may also be affected by sample size and geographical location. With regard to sample size, the results varied from too small a sample to provide significant results to a sufficiently large sample to provide significant conclusions, thus limiting the ability to compare statistical significance between studies [ 64 ]. Moreover, the varied geographical settings, in terms of location and setting characteristics, make it difficult to assume that studies are representative of the country in which they were conducted, thus also meaning that international comparisons are unsuitable and unreliable.…”

“…All studies, except one, included a molecular analysis of deletions (the majority by PCR), with only a few using microsatellites. Although almost all studies used PCR, a wide variety of primers or conditions were used for amplification [ 64 ]. Moreover, some articles reported using sequencing, but only for the analysis of sequence variations rather than to confirm gene presence or deletion.…”

“…Accordingly, none of the studies that did not test the quality of their samples can assume the reliability of their results [ 37 , 68 ]. To achieve that, studies should report the amplification of at least two different P. falciparum genes, for example pfmsp1 and pfmsp2 [ 12 , 64 , 69 ] . This is useful to check the quality of the DNA or the concentration to be amplified in order to ensure that, if PCR for pfhrp2 and pfhrp3 does not amplify, there is actually a problem with the DNA used rather than a deletion.…”

“…Some studies also analysed parasite density by qPCR, which allows the quality and quantity of the DNA to be tested simultaneously [ 22 , 29 ]. These studies were able to avoid confusing false-negative RDT results caused by low density with those caused by eliminations [ 64 , 70 ]. However, as this review shows, the majority of studies (n = 33) did not check the parasite density.…”