Optimizing Strategic Insecticide Resistance Management Planning in Malaria Vectors

In the past decade, there has been rapid scale-up of insecticide-based malaria vector control in the context of integrated vector management (IVM). But, the continued efficacy of vector control interventions is threatened by the selection of insecticide resistance. Evidence of insecticide resistance operationally undermining malaria vector control programmes is invariably mounting and is resulting in policy changes. Monitoring and management of resistant disease vectors is essential to limit the selection and spread of insecticide resistance and to maintain the effectiveness of vector control. Thus, countries are encouraged to implement pre-emptive insecticide resistance management (IRM) strategies against malaria vectors according to the Global Plan for IRM. However, substantial challenges for implementation exist at country level. The IVM strategy provides a potential platform that could be exploited for enhanced national strategic IRM planning and operationalisation. Nevertheless, significant coordinated response among stakeholders and political commitment is needed for timely and effective policy implementation within the context of a national health system

Exploiting the Potential of Integrated Vector Management for Combating Malaria in Africa

Integrated Vector Management (IVM) is advocated by the World Health Organization (WHO) as the pivotal platform for vector control. The threat for malaria and emerging and re-emerging vector borne diseases is increasing. However, adoption and deployment of the IVM strategy has been minimal. Though malaria endemic countries are embracing and consolidating the IVM approach, real time entomological data on transmission risk and targeting the right vector with the appropriate intervention is lacking. IVM could be harnessed for circumventing operational constraints for vector control. Herein IVM for combating malaria and other insect-borne diseases is reviewed and ways to maximize its potential and benefits are proposed. IVM promotes operational research for evidence-based, cost-effective and optimally sustainable vector control with judicious integration of available options, improves management of insecticides, and effective mitigation of potential negative health and environmental impacts. IVM enhances institutional arrangements including accountability, collaboration and coordination of stakeholders. IVM will require policies and frameworks to maximize intervention impact; and infrastructure and human resources capacity, community involvement and information sharing, strengthened regulation for registration and quality assurance, procurement, financial management and supply chain management for commodities. However, national health system-based response among stakeholders and political commitment is needed for optimal IVM implementation

Numerical modelling of monorail support requirements in decline development

This paper discusses support requirements for the proposed monorail system to be used in decline development. The monorail drilling and loading systems are systems that move on the rail (monorail) installed in the roof of the decline and supported by roof bolts, suspension chains and steel supports. However, due to the weight of the components of the two systems, it is imperative that the force in each roof bolt, suspension chain and steel support capable of suspending the weight of the heaviest component is determined. Numerical models that relate the weight of the monorail drilling and loading components to the required strength in the support system have been developed. Using these developed models, numerical values of the forces in each roof bolt, suspension chain and steel support, required to suspend the weight of the heaviest component of the monorail drilling and loading systems are determined

Optimizing impact assessment of entomological intervention for malaria control in an operational setting in Zambia

The study aimed at optimally assessing the impact of indoor residual spraying (IRS) and insecticide treated nets (ITNs) on vector species abundance, their infectivity and resistance status, and Plasmodium falciparum prevalence, malaria deaths and case fatality rates in the human population. Malaria prevalence surveys were conducted and routine surveillance data was retrospectively analyzed. The average P. falciparum prevalence in children between the ages of 1 and 14 years was below 10% across the study period. The intervention effect was more pronounced in IRS areas than in ITNs localities but with an incremental protective effect of their combined use. Age-specific comparison showed better intervention effect on children below 5 years than older children 5 to 14 years old. While the average number of deaths and case fatality rates in children under the age of five plunged precipitately, the reductions were more significant in IRS districts than in ITNs districts. Results indicate the need for supplementing parasite prevalence survey data with routine surveillance data in low transmission intensity areas and demonstrate the significance of evidence-based age-specific deployment of interventions. To monitor vector species abundance and infectivity, mosquitoes were collected daily using exit window traps. The three major vectors; An. gambiae s.s, An. arabiensis and An. funestus s.s, and three potential vectors of malaria, An. nili, An. rivulorum and An. funestus-like species were identified. Overall, the biggest impact of IRS and ITNs was on An. gambiae s.s, and An. funestus abundance. No An. gambiae s.s was collected in IRS localities, thus validating the fact that An. gambiae s.s and An. funestus are characteristically more amenable to control by IRS and ITNs than An. arabiensis. The transmission potential for all malaria vectors, as expressed by the calculated transmission index, was zero as none of the trapped mosquitoes tested positive for P. falciparum sporozoites. The identification of An. nili, An. rivulorum and An. funestus-like necessitate further research to determine their role in malaria transmission in the country. The low numbers of mosquitoes collected also indicate a compromise in the efficiency of exit window traps in low transmission settings, suggesting the need for their replacement with a more robust collection tool like the CDC light trap. While the persistence of An. arabiensis suggests the presence of resistance segregating in this population or, that this outdoor species is not in contact with IRS or ITNs, it could as well imply that it’s the one species perpetuating malaria transmission in these meso-to hypo- endemic areas. To determine the impact of interventions on insecticide resistance status of malaria vectors, susceptibility assays using the WHO standard protocol were conducted in 17 localities. High levels of resistance were detected in both An, gambiae s.l and An, funestus s.l to pyrethroids and DDT but with 100% susceptibility to malathion and bendiocarb. The level of resistance was significantly higher in IRS areas than in ITN areas. These findings indicate that resistance has been selected for following extensive vector control. Resistance to both DDT and deltamethrin in IRS localities and ITN areas with intense cotton growing was detected suggesting selection due to either historical use of DDT, gene flow or cross-resistance. All An. gambiae s.s were molecular s-forms and only the west (leu-phe) kdr was detected. Complete susceptibility to the organophosphates and carbamates provides a possibility to switch to these alternative insecticide classes for IRS. The detected increases in the malaria prevalence in localities with high insecticide resistance levels indicate vector control failure. These findings point to the need for information on underlying biochemical and molecular resistance mechanisms to make possible the design of an effective resistance management strategy, and for the assessment of the impact of resistance on interventions. The results indicate that the impact of malaria control can be optimally assessed by using a combination of epidemiological (routine surveillance and prevalence data) and entomological indicators, in the context of a malaria decision support system, to enhance policy formulation for objective implementation of malaria control interventions and rational use of available resources

Using a Geographical-Information-System-Based Decision Support to Enhance Malaria Vector Control in Zambia

Geographic information systems (GISs) with emerging technologies are being harnessed for studying spatial patterns in vector-borne diseases to reduce transmission. To implement effective vector control, increased knowledge on interactions of epidemiological and entomological malaria transmission determinants in the assessment of impact of interventions is critical. This requires availability of relevant spatial and attribute data to support malaria surveillance, monitoring, and evaluation. Monitoring the impact of vector control through a GIS-based decision support (DSS) has revealed spatial relative change in prevalence of infection and vector susceptibility to insecticides and has enabled measurement of spatial heterogeneity of trend or impact. The revealed trends and interrelationships have allowed the identification of areas with reduced parasitaemia and increased insecticide resistance thus demonstrating the impact of resistance on vector control. The GIS-based DSS provides opportunity for rational policy formulation and cost-effective utilization of limited resources for enhanced malaria vector control

Dengue fever outbreaks in Eritrea, 2005-2015: a case for strengthening surveillance, control and reporting

BACKGROUND: The geographic distribution and burden of dengue is increasing globally. This study aims to evaluate dengue outbreaks and to substantiate the need for strengthened surveillance, reporting and control in Eritrea. METHODS: Data from two cross-sectional dengue epidemic investigations in 2005 and 2010 were analyzed. Samples were tested for dengue virus-specific IgM and IgG antibodies using capture enzyme-linked immunosorbent assays. Dengue vectors' breeding attributes were characterized and epidemic risk indices determined. National routine surveillance weekly reports from 2005 to the second quarter of 2015 were analyzed for spatiotemporal trends. RESULTS: Dengue outbreaks increased in Eritrea from 2005 to 2015 with clinical presentation varying markedly among patients. The house and container indices for Aedes aegypti were 40 and 39.6 % respectively, with containers having A. aeqypti varying significantly (P < 0.04). Serum from 33.3 % (n = 15) and 88 % (n = 26) of clinical dengue cases in Aroget sub-Zoba (district) of Gash Barka Zoba (region) contained anti-DENV IgM antibody in 2005 and 2006, respectively. The national surveillance data from 2005 to 2015 indicate an overall spatiotemporal increase of dengue fever. CONCLUSIONS: The increase in dengue outbreaks has been confirmed in Eritrea and necessitates strengthening of surveillance and health worker and laboratory capacity, as well as targeted vector control interventions

Women’s dietary diversity changes seasonally in Malawi and Zambia

Objective: There is growing recognition of the role that seasonality plays in agricultural production, expenditure, food security, diet quality and nutritional status, however, annual or bi-annual surveys may not capture seasonal or intra-seasonal shifts in dietary intake which can inform agriculture and nutrition policies, programming, and monitoring and evaluation. Design, Setting and Participants: Seasonal variation in diets of women of reproductive age (WRA) living in rural Malawi and Zambia were measured bimonthly for eleven rounds, from September 2017 to May 2019. Trained enumerators collected data on a sample of 200 women using a qualitative 24-hour list-based recall of food items consumed, based on the ten food groups for Minimum Dietary Diversity of Women (MDD-W). Results and Conclusion: There were significant seasonal fluctuations in the percentage of women achieving MDD-W, ranging from a low of 18% to a high of 82%. MDD-W followed expected fluctuations, peaking during harvest season and lowering during lean season, however, there were unexpected highs and lows at other times, demonstrating the importance of regular monitoring. The study demonstrated significant seasonal fluctuations in the proportion of WRA achieving MDD-W, having implications for project monitoring and evaluation. The research provides evidence of periods of abundance and scarcity for nutritionally important food groups

Insecticide resistance and the future of malaria control in Zambia.

BACKGROUND: In line with the Global trend to improve malaria control efforts a major campaign of insecticide treated net distribution was initiated in 1999 and indoor residual spraying with DDT or pyrethroids was reintroduced in 2000 in Zambia. In 2006, these efforts were strengthened by the President's Malaria Initiative. This manuscript reports on the monitoring and evaluation of these activities and the potential impact of emerging insecticide resistance on disease transmission. METHODS: Mosquitoes were captured daily through a series of 108 window exit traps located at 18 sentinel sites. Specimens were identified to species and analyzed for sporozoites. Adult Anopheles mosquitoes were collected resting indoors and larva collected in breeding sites were reared to F1 and F0 generations in the lab and tested for insecticide resistance following the standard WHO susceptibility assay 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 14 years. RESULTS: A total of 619 Anopheles gambiae s.l. and 228 Anopheles funestus s.l. were captured from window exit traps throughout the period, of which 203 were An. gambiae malaria vectors and 14 An. funestus s.s.. In 2010 resistance to DDT and the pyrethroids deltamethrin, lambda-cyhalothrin and permethrin was detected in both An. gambiae s.s. and An. funestus s.s.. No sporozoites were detected in either species. Prevalence of P. falciparum in the sentinel sites remained below 10% throughout the study period. CONCLUSION: Both An. gambiae s.s. and An. funestus s.s. were controlled effectively with the ITN and IRS programme in Zambia, maintaining a reduced disease transmission and burden. However, the discovery of DDT and pyrethroid resistance in the country threatens the sustainability of the vector control programme

Six decades of malaria vector control in southern Africa : a review of the entomological evidence-base

AVAILABILITY OF DATA AND MATERIALS : Information was searched and obtained from published data in the PubMed search engine. The datasets used and/or analysed during this study can be obtained from the corresponding author on reasonable request.BACKGROUND : Countries in the southern Africa region have set targets for malaria elimination between 2020 and 2030. Malaria vector control is among the key strategies being implemented to achieve this goal. This paper critically reviews published entomological research over the past six decades in three frontline malaria elimination countries namely, Botswana Eswatini and Namibia, and three second-line malaria elimination countries including Mozambique, Zambia, and Zimbabwe. The objective of the review is to assess the current knowledge and highlight gaps that need further research attention to strengthen evidence-based decision-making toward malaria elimination. METHODS : Publications were searched on the PubMed engine using search terms: “(malaria vector control OR vector control OR malaria vector*) AND (Botswana OR Swaziland OR Eswatini OR Zambia OR Zimbabwe OR Mozambique)”. Opinions, perspectives, reports, commentaries, retrospective analysis on secondary data protocols, policy briefs, and reviews were excluded. RESULTS : The search resulted in 718 publications with 145 eligible and included in this review for the six countries generated over six decades. The majority (139) were from three countries, namely Zambia (59) and Mozambique (48), and Zimbabwe (32) whilst scientific publications were relatively scanty from front-line malaria elimination countries, such as Namibia (2), Botswana (10) and Eswatini (4). Most of the research reported in the publications focused on vector bionomics generated mostly from Mozambique and Zambia, while information on insecticide resistance was mostly available from Mozambique. Extreme gaps were identified in reporting the impact of vector control interventions, both on vectors and disease outcomes. The literature is particularly scanty on important issues such as change of vector ecology over time and space, intervention costs, and uptake of control interventions as well as insecticide resistance. CONCLUSIONS : The review reveals a dearth of information about malaria vectors and their control, most noticeable among the frontline elimination countries: Namibia, Eswatini and Botswana. It is of paramount importance that malaria vector research capacity and routine entomological monitoring and evaluation are strengthened to enhance decision-making, considering changing vector bionomics and insecticide resistance, among other determinants of malaria vector control.The AFRO-II Project under the auspices of the Global Environment Facility/United Nations Environment Programme (GEF/UNEP) through the World Health Organization Regional Office for Africa (WHO-AFRO); icipe’s core donors, the Foreign, Commonwealth & Development Office (FCDO) of the UK Government; Swedish International Development Cooperation Agency (Sida); the Swiss Agency for Development and Cooperation (SDC); Federal Democratic Republic of Ethiopia; and the Kenyan Government.https://malariajournal.biomedcentral.comhj2023School of Health Systems and Public Health (SHSPH