The highly polymorphic CYP6M7 cytochrome P450 gene partners with the directionally selected CYP6P9a and CYP6P9b genes to expand the pyrethroid resistance front in the malaria vector Anopheles funestus in Africa

Background: Pyrethroid resistance in the major malaria vector Anopheles funestus is rapidly expanding across Southern Africa. It remains unknown whether this resistance has a unique origin with the same molecular basis or is multifactorial. Knowledge of the origin, mechanisms and evolution of resistance are crucial to designing successful resistance management strategies. Results: Here, we established the resistance profile of a Zambian An. funestus population at the northern range of the resistance front. Similar to other Southern African populations, Zambian An. funestus mosquitoes are resistant to pyrethroids and carbamate, but in contrast to populations in Mozambique and Malawi, these insects are also DDT resistant. Genome-wide microarray-based transcriptional profiling and qRT-PCR revealed that the cytochrome P450 gene CYP6M7 is responsible for extending pyrethroid resistance northwards. Indeed, CYP6M7 is more over-expressed in Zambia [fold-change (FC) 37.7; 13.2 for qRT-PCR] than CYP6P9a (FC15.6; 8.9 for qRT-PCR) and CYP6P9b (FC11.9; 6.5 for qRT-PCR), whereas CYP6P9a and CYP6P9b are more highly over-expressed in Malawi and Mozambique. Transgenic expression of CYP6M7 in Drosophila melanogaster coupled with in vitro assays using recombinant enzymes and assessments of kinetic properties demonstrated that CYP6M7 is as efficient as CYP6P9a and CYP6P9b in conferring pyrethroid resistance. Polymorphism patterns demonstrate that these genes are under contrasting selection forces: the exceptionally diverse CYP6M7 likely evolves neutrally, whereas CYP6P9a and CYP6P9b are directionally selected. The higher variability of CYP6P9a and CYP6P9b observed in Zambia supports their lesser role in resistance in this country. Conclusion: Pyrethroid resistance in Southern Africa probably has multiple origins under different evolutionary forces, which may necessitate the design of different resistance management strategies

The emergence of insecticide resistance in central Mozambique and potential threat to the successful indoor residual spraying malaria control programme.

BACKGROUND: Malaria vector control by indoor residual spraying was reinitiated in 2006 with DDT in Zambézia province, Mozambique. In 2007, these efforts were strengthened by the President's Malaria Initiative. This manuscript reports on the monitoring and evaluation of this programme as carried out by the Malaria Decision Support Project. METHODS: Mosquitoes were captured daily through a series of 114 window exit traps located at 19 sentinel sites, identified to species and analysed for sporozoites. Anopheles mosquitoes were collected resting indoors and tested for insecticide resistance following the standard WHO protocol. Annual cross sectional household parasite surveys were carried out to monitor the impact of the control programme on prevalence of Plasmodium falciparum in children aged 1 to 15 years. RESULTS: A total of 3,769 and 2,853 Anopheles gambiae s.l. and Anopheles funestus, respectively, were captured from window exit traps throughout the period. In 2010 resistance to the pyrethroids lambda-cyhalothrin and permethrin and the carbamate, bendiocarb was detected in An. funestus. In 2006, the sporozoite rate in An. gambiae s.s. was 4% and this reduced to 1% over 4 rounds of spraying. The sporozoite rate for An. funestus was also reduced from 2% to 0 by 2008. Of the 437 Anopheles arabiensis identified, none were infectious. Overall prevalence of P. falciparum in the sentinel sites fell from 60% to 32% between October 2006 and October 2008. CONCLUSION: Both An. gambiae s.s. and An. funestus were controlled effectively with the DDT-based IRS programme in Zambézia, reducing disease transmission and burden. However, the discovery of pyrethroid resistance in the province and Mozambique's policy change away from DDT to pyrethroids for IRS threatens the gains made here

The origin and insecticide resistance of Aedes albopictus mosquitoes established in southern Mozambique

Background: The Aedes albopictus mosquito is of medical concern due to its ability to transmit viral diseases, such as dengue and chikungunya. Aedes albopictus originated in Asia and is now present on all continents, with the exception of Antarctica. In Mozambique, Ae. albopictus was first reported in 2015 within the capital city of Maputo, and by 2019, it had become established in the surrounding area. It was suspected that the mosquito population originated in Madagascar or islands of the Western Indian Ocean (IWIO). The aim of this study was to determine its origin. Given the risk of spreading insecticide resistance, we also examined relevant mutations in the voltage-sensitive sodium channel (VSSC). Methods: Eggs of Ae. albopictus were collected in Matola-Rio, a municipality adjacent to Maputo, and reared to adults in the laboratory. Cytochrome c oxidase subunit I (COI) sequences and microsatellite loci were analyzed to estimate origins. The presence of knockdown resistance (kdr) mutations within domain II and III of the VSSC were examined using Sanger sequencing. Results: The COI network analysis denied the hypothesis that the Ae. albopictus population originated in Madagascar or IWIO; rather both the COI network and microsatellites analyses showed that the population was genetically similar to those in continental Southeast Asia and Hangzhou, China. Sanger sequencing determined the presence of the F1534C knockdown mutation, which is widely distributed among Asian populations, with a high allele frequency (46%). Conclusions: These results do not support the hypothesis that the Mozambique Ae. albopictus population originated in Madagascar or IWIO. Instead, they suggest that the origin is continental Southeast Asia or a coastal town in China.Parasites and Vectors, 17(1), art. no. 292; 2024journal articl

Escalation of pyrethroid resistance in the malaria vector Anopheles funestus induces a loss of efficacy of PBO-based insecticide-treated nets in Mozambique

BackgroundInsecticide resistance poses a serious threat to insecticide-based interventions in Africa. There is a fear that resistance escalation could jeopardize malaria control efforts. Monitoring cases of aggravation of resistance intensity and its impact on the efficacy of control tools is crucial to predict consequences of resistance.MethodsThe resistance levels of an Anopheles funestus population from Palmeira in southern Mozambique was characterised and its impact on the efficacy of various insecticide-treated nets established.ResultsA dramatic loss of efficacy of all long lasting insecticidal nets (LLINs) including PBO-based nets (Olyset Plus) was observed. This An. funestus population consistently (2016, 2017 and 2018) exhibited high degree of pyrethroid resistance. Molecular analyses revealed that this resistance escalation was associated with a massive over-expression of duplicated cytochrome P450 genes, CYP6P9a/b and also the fixation of the resistance CYP6P9a_R allele in this population in 2016 (100%) in contrast to 2002 (5%). However, the low recovery of susceptibility after PBO synergist assay suggests that other resistance mechanisms could be involved.ConclusionsThe loss of efficacy of pyrethroid-based LLINs with and without PBO is a concern for the effectiveness of insecticide-based intervention and action should be taken to prevent the spread of such super-resistance.</p

Covid-19 – Situação de Contingência – Desafios para a Educação. Situações Vivenciadas em Escolas Moçambicanas

The highlighted theme is approached by three pairs of students of the Master Course in Pedagogy and Didactics (MPD) focusing on the concerns that recently have agitated the school environment. The first pair of students aims to bring the relationship between public health and school health within the scope of Covid-19 as a necessary element to ensure a good learning environment for pedagogical success emphasizing that the intention of school health education is to establish conditions for students to build knowledge about it and so keep on in the learning process. The second pair based on the idea that the crisis imposed by the pandemic constitutes a global threat, supported by bibliographic research, presents the main measures taken by schools in order to stop the spread of the pandemic as well as to understand and accept the rationality of the adopted strategies for the continuity of the learning process during the class suspension time and after the face-to-face resumption. The third pair reflects on the effect of the situation currently experienced in formal education in Mozambique aiming at school education centered on new directions based on a reflection on certain current changes resulting from the complex global situation. Considering that sustainability for the plan to return to face-to-face classes requires the improvement of hygiene conditions in schools and other community safety measures, the essence of social sentiment is highlighted. In view of the MPD students’ contributions, two teachers focus on the challenges launched by Covid-19 to Education, namely in regard to the learning environments and the importance of mediation to be maintained by teachers in the new focus with which the teaching-learning process must be engaged.A temática em destaque é abordada por três pares de estudantes do Curso de Mestrado em Pedagogia e Didáctica (MPD), concentrando-se nas preocupações que, nos últimos tempos, agitam o ambiente escolar. O primeiro objectiva trazer a relação entre a saúde pública e a saúde escolar, no âmbito da pandemia de Covid-19, como elemento necessário para o garante do bom ambiente de aprendizagem e do sucesso pedagógico, realçando que a intenção da educação em criar condições de saúde escolar é firmar a necessidade de que os alunos devem construir conhecimentos sobre a mesma. O segundo, partindo da ideia de que a crise imposta pela pandemia constitui uma ameaça global, sustentado numa pesquisa bibliográfica, apresenta as principais medidas tomadas pelas escolas, de modo a conter a propagação da pandemia, bem como a racionalidade das estratégias adoptadas, para a continuidade das aulas durante o fecho e após a retoma presencial. O terceiro par reflecte sobre o efeito da situação vivenciada actualmente, no ensino formal em Moçambique, almejando uma educação escolar imbuída de novos rumos, tendo por base uma reflexão sobre certas mudanças actuais, decorrentes do quadro global complexo. Considerando que a sustentabilidade para o plano de retoma das aulas presenciais exige a melhoria das condições de higiene nas escolas e de outras medidas de segurança comunitária, a essência do sentimento social é posta em destaque. Face aos contributos dos estudantes, dois professores do MPD centram-se nos desafios lançados pela pandemia Covid-19 à Educação, nomeadamente, no que concerne a ambientes de aprendizagem que possam dar respostas às dificuldades encontradas e à importância da mediação a ser mantida pelos professores, no novo enfoque com que o processo ensino-aprendizagem se depara

High Level of Pyrethroid Resistance in an Anopheles funestus Population of the Chokwe District in Mozambique

Background Although Anopheles funestus is difficult to rear, it is crucial to analyse field populations of this malaria vector in order to successfully characterise mechanisms of insecticide resistance observed in this species in Africa. In this study we carried out a large-scale field collection and rearing of An. funestus from Mozambique in order to analyse its susceptibility status to insecticides and to broadly characterise the main resistance mechanisms involved in natural populations. Methodology/Principal Findings 3,000 F1 adults were obtained through larval rearing. WHO susceptibility assays indicated a very high resistance to pyrethroids with no mortality recorded after 1h30min exposure and less than 50% mortality at 3h30min. Resistance to the carbamate, bendiocarb was also noted, with 70% mortality after 1h exposure. In contrast, no DDT resistance was observed, indicating that no kdr-type resistance was involved. The sequencing of the acetylcholinesterase gene indicated the absence of the G119S and F455W mutations associated with carbamate and organophosphate resistance. This could explain the absence of malathion resistance in this population. Both biochemical assays and quantitative PCR implicated up-regulated P450 genes in pyrethroid resistance, with GSTs playing a secondary role. The carbamate resistance observed in this population is probably conferred by the observed altered AChE with esterases also involved. Conclusion/Significance The high level of pyrethroid resistance in this population despite the cessation of pyrethroid use for IRS in 1999 is a serious concern for resistance management strategies such as rotational use of insecticides. As DDT has now been re-introduced for IRS, susceptibility to DDT needs to be closely monitored to prevent the appearance and spread of resistance to this insecticide

Attrition, physical integrity and insecticidal activity of long-lasting insecticidal nets in sub-Saharan Africa and modelling of their impact on vectorial capacity

Long-lasting insecticidal nets (LLINs) are the primary malaria prevention and control intervention in many parts of sub-Saharan Africa. While LLINs are expected to last at least 3 years under normal use conditions, they can lose effectiveness because they fall out of use, are discarded, repurposed, physically damaged, or lose insecticidal activity. The contributions of these different interrelated factors to durability of nets and their protection against malaria have been unclear.; Starting in 2009, LLIN durability studies were conducted in seven countries in Africa over 5 years. WHO-recommended measures of attrition, LLIN use, insecticidal activity, and physical integrity were recorded for eight different net brands. These data were combined with analyses of experimental hut data on feeding inhibition and killing effects of LLINs on both susceptible and pyrethroid resistant malaria vectors to estimate the protection against malaria transmission-in terms of vectorial capacity (VC)-provided by each net cohort over time. Impact on VC was then compared in hypothetical scenarios where one durability outcome measure was set at the best possible level while keeping the others at the observed levels.; There was more variability in decay of protection over time by country than by net brand for three measures of durability (ratios of variance components 4.6, 4.4, and 1.8 times for LLIN survival, use, and integrity, respectively). In some countries, LLIN attrition was slow, but use declined rapidly. Non-use of LLINs generally had more effect on LLIN impact on VC than did attrition, hole formation, or insecticide loss.; There is much more variation in LLIN durability among countries than among net brands. Low levels of use may have a larger impact on effectiveness than does variation in attrition or LLIN degradation. The estimated entomological effects of chemical decay are relatively small, with physical decay probably more important as a driver of attrition and non-use than as a direct cause of loss of effect. Efforts to maximize LLIN impact in operational settings should focus on increasing LLIN usage, including through improvements in LLIN physical integrity. Further research is needed to understand household decisions related to LLIN use, including the influence of net durability and the presence of other nets in the household

Living on the edge : a longitudinal study of Anopheles funestus in an isolated area of Mozambique

Understanding the survival strategies of malaria vectors at the edges of their distribution, where they are under stress from environmental conditions, may lead to the development of novel control techniques and may help predict the effects of climate change on these mosquitoes.; The population dynamics of an isolated population of Anopheles funestus from the peninsula of Linga Linga in southern Mozambique was studied over a period of 104 weeks from March 2009 to May 2011 by 917 light-trap and 390 exit collections, mostly in an area close to a seasonal pond.; Over the sampling period, 3,684 An. funestus females were caught. Densities decreased with increasing distance from the pond. In 2009 and 2010, a single annual peak in An. funestus density coincident with the single annual peak in rainfall was observed, but a clear population peak was absent during the first 21 weeks of 2011. In between population peaks, An. funestus remained present at low densities. In light trap collections, the proportion of gravid mosquitoes was significantly higher during the 'low season' (the period between peaks) than during the peak season (RR = 4.3, p>0.001). In contrast, in exit collections, the proportion of gravid mosquitoes was significantly lower during low season than during the peak season (RR = 0.64, p>0.01). Also, in light traps, the proportion of part-fed females was higher during the low season than during the peak season (RR = 4.5, p>0.001), whereas this was inversed for engorged females (RR = 0.46, p>0.05).Thirteen out of 289 (4.5%) An. funestus tested positive in the sporozoite ELISA. The proportion of sporozoite positive females was higher during the low season (6.25%, six out of 96) than during the peaks (3.63%, seven out of 193), but this difference was not significant.; It is suggested that a proportion of the mosquito population may become gonotrophically discordant during the long dry season resulting in enhanced mosquito survival and sustained malaria transmission