Evidence of pyrethroid resistance in Anopheles amharicus and Anopheles arabiensis from Arjo-Didessa irrigation scheme, Ethiopia

Background Indoor residual spraying and insecticide-treated nets are among the key malaria control intervention tools. However, their efficacy is declining due to the development and spread of insecticide resistant vectors. In Ethiopia, several studies reported resistance of An. arabiensis to multiple insecticide classes. However, such data is scarce in irrigated areas of the country where insecticides, pesticides and herbicides are intensively used. Susceptibility of An. gambiae s.l. to existing and new insecticides and resistance mechanisms were assessed in Arjo-Didessa sugarcane plantation area, southwestern Ethiopia. Methods Adult An. gambiae s.l. reared from larval/pupal collections of Arjo-Didessa sugarcane irrigation area and its surrounding were tested for their susceptibility to selected insecticides. Randomly selected An. gambiae s.l. (dead and survived) samples were identified to species using species-specific polymerase chain reaction (PCR) and were further analyzed for the presence of knockdown resistance (kdr) alleles using allele-specific PCR. Results Among the 214 An. gambiae s.l. samples analyzed by PCR, 89% (n = 190) were An. amharicus and 9% (n = 20) were An. arabiensis. Mortality rates of the An. gambiae s.l. exposed to deltamethrin and alphacypermethrin were 85% and 86.8%, respectively. On the other hand, mortalities against pirmiphos-methyl, bendiocarb, propoxur and clothianidin were 100%, 99%, 100% and 100%, respectively. Of those sub-samples (An. amharicus and An. arabiensis) examined for presence of kdr gene, none of them were found to carry the L1014F (West African) allelic mutation. Conclusion Anopheles amharicus and An. arabiensis from Arjo-Didessa sugarcane irrigation area were resistant to pyrethroids which might be synergized by extensive use of agricultural chemicals. Occurrence of pyrethroid resistant malaria vectors could challenge the ongoing malaria control and elimination program in the area unless resistance management strategies are implemented. Given the resistance of An. amharicus to pyrethroids, its behavior and vectorial capacity should be further investigated.

Design and methods for a quasi-experimental pilot study to evaluate the impact of dual active ingredient insecticide-treated nets on malaria burden in five regions in sub-Saharan Africa

Background Vector control tools have contributed significantly to a reduction in malaria burden since 2000, primarily through insecticidal-treated bed nets (ITNs) and indoor residual spraying. In the face of increasing insecticide resistance in key malaria vector species, global progress in malaria control has stalled. Innovative tools, such as dual active ingredient (dual-AI) ITNs that are effective at killing insecticide-resistant mosquitoes have recently been introduced. However, large-scale uptake has been slow for several reasons, including higher costs and limited evidence on their incremental effectiveness and cost-effectiveness. The present report describes the design of several observational studies aimed to determine the effectiveness and cost-effectiveness of dual-AI ITNs, compared to standard pyrethroid-only ITNs, at reducing malaria transmission across a variety of transmission settings. Methods Observational pilot studies are ongoing in Burkina Faso, Mozambique, Nigeria, and Rwanda, leveraging dual-AI ITN rollouts nested within the 2019 and 2020 mass distribution campaigns in each country. Enhanced surveillance occurring in select study districts include annual cross-sectional surveys during peak transmission seasons, monthly entomological surveillance, passive case detection using routine health facility surveillance systems, and studies on human behaviour and ITN use patterns. Data will compare changes in malaria transmission and disease burden in districts receiving dual-AI ITNs to similar districts receiving standard pyrethroid-only ITNs over three years. The costs of net distribution will be calculated using the provider perspective including financial and economic costs, and a cost-effectiveness analysis will assess incremental cost-effectiveness ratios for Interceptor® G2, Royal Guard®, and piperonyl butoxide ITNs in comparison to standard pyrethroid-only ITNs, based on incidence rate ratios calculated from routine data. Conclusions Evidence of the effectiveness and cost-effectiveness of the dual-AI ITNs from these pilot studies will complement evidence from two contemporary cluster randomized control trials, one in Benin and one in Tanzania, to provide key information to malaria control programmes, policymakers, and donors to help guide decision-making and planning for local malaria control and elimination strategies. Understanding the breadth of contexts where these dual-AI ITNs are most effective and collecting robust information on factors influencing comparative effectiveness could improve uptake and availability and help maximize their impact.

Vector composition, abundance, biting patterns and malaria transmission intensity in Madang, Papua New Guinea: assessment after 7 years of an LLIN-based malaria control programme

Background A malaria control programme based on distribution of long-lasting insecticidal bed nets (LLINs) and artemisinin combination therapy began in Papua New Guinea in 2009. After implementation of the programme, substantial reductions in vector abundance and malaria transmission intensity occurred. The research reported here investigated whether these reductions remained after seven years of sustained effort. Methods All-night (18:00 to 06:00) mosquito collections were conducted using human landing catches and barrier screen methods in four villages of Madang Province between September 2016 and March 2017. Anopheles species identification and sporozoite infection with Plasmodium vivax and Plasmodium falciparum were determined with molecular methods. Vector composition was expressed as the relative proportion of different species in villages, and vector abundance was quantified as the number of mosquitoes per barrier screen-night and per person-night. Transmission intensity was quantified as the number of sporozoite-infective vector bites per person-night. Results Five Anopheles species were present, but vector composition varied greatly among villages. Anopheles koliensis, a strongly anthropophilic species was the most prevalent in Bulal, Matukar and Wasab villages, constituting 63.7–73.8% of all Anopheles, but in Megiar Anopheles farauti was the most prevalent species (97.6%). Vector abundance varied among villages (ranging from 2.8 to 72.3 Anopheles per screen-night and 2.2–31.1 Anopheles per person-night), and spatially within villages. Malaria transmission intensity varied among the villages, with values ranging from 0.03 to 0.5 infective Anopheles bites per person-night. Most (54.1–75.1%) of the Anopheles bites occurred outdoors, with a substantial proportion (25.5–50.8%) occurring before 22:00. Conclusion The estimates of vector abundance and transmission intensity in the current study were comparable to or higher than estimates in the same villages in 2010–2012, indicating impeded programme effectiveness. Outdoor and early biting behaviours of vectors are some of the likely explanatory factors. Heterogeneity in vector composition, abundance and distribution among and within villages challenge malaria control programmes and must be considered when planning them.

Impact of Drug Pressure versus Limited Access to Drug in Malaria Control: The Dilemma

Malaria burden has severe impact on the world. Several arsenals, including the use of antimalarials, are in place to curb the malaria burden. However, the application of these antimalarials has two extremes, limited access to drug and drug pressure, which may have similar impact on malaria control, leading to treatment failure through divergent mechanisms. Limited access to drugs ensures that patients do not get the right doses of the antimalarials in order to have an effective plasma concentration to kill the malaria parasites, which leads to treatment failure and overall reduction in malaria control via increased transmission rate. On the other hand, drug pressure can lead to the selection of drug resistance phenotypes in a subpopulation of the malaria parasites as they mutate in order to adapt. This also leads to a reduction in malaria control. Addressing these extremes in antimalarial application can be essential in maintaining the relevance of the conventional antimalarials in winning the war against malaria.

EFEKTIVITAS KELAMBU BERINSEKTISIDA DALAM PENGENDALIAN VEKTOR MALARIA DI INDONESIA

Malaria is still a health problem in several parts of Indonesia. National malaria elimination is targeted at 2030. One of the programs carried out by the government in malaria control to achieve elimination is the mass distribution and use of insecticide-treated mosquito nets. The use of insecticide-treated mosquito nets is one of the efforts to reduce malaria cases through vector control. Insecticide mosquito nets are recommended as a strategic step to break the chain of malaria transmission because the insecticide content in the treated fibers can kill mosquitoes. The data used in this paper is data on the percentage of mosquito mortality from the efficacy test of insecticide-treated mosquito nets to see the killing power of mosquito nets which is then used to assess the effectiveness of mosquito nets in vector control. The data were obtained from scientific studies of articles published in scientific journals. From the data collected, it is known that some insecticide-treated mosquito nets used by the community are effective in vector control, but some are no longer effective. The best period for using mosquito nets is less than 6 months by paying attention to the proper washing method so that insecticide-treated mosquito nets are still effective.

The Durability, Functionality and Acceptability of Novel Screened Doors and Windows After Four Years of Use in A Gambian Village: A Cross-Sectional Survey

Background: The World Health Organization recommends house screening as a tool for malaria control, yet evidence of the long-term durability, functionality and acceptability of this intervention is lacking. Here we examined the sustainability and use of novel types of screened doors and windows four years after installation in a Gambian village. Methods: A survey of 31 houses, each with two screened doors and two screened windows, was conducted in the rainy season. There were four types of screened door and two types of screened window. Trained staff carried out the survey and interviews of room owners were conducted in the local language before translation into English.Results: Structurally, the manufactured doors and windows were highly durable and in excellent condition. Most doors shut smoothly 50/61 (82%), although only 25/61 (41%) shut fully automatically with the latch slotting into the hole on the frame and holding fast. Door locks were less robust, with only (24/61) 39% present and working. Blinds proved especially flimsy, with only 4/109 (4%) of door blinds and 10/56 (18%) of window blinds present and in working order. Householders hung curtains inside most doors 50/61 (82%) and in 26/61 (43%) of the windows. Front doors were commonly found propped open 21/31 (68%) and 23/27 (85%) of those with a front door curtain, put their curtains down at night. Doors and windows were well liked, 19/31 (61%) of respondents were happy with them because they kept mosquitoes out 14/31 (45%) and provided security 12/31 (39%). The main reason given for the use of curtains was to provide privacy 26/28 (93% of those with curtains), especially while the door was open or had ‘see-through’ panels.Conclusions: Overall, the screened doors and windows were in excellent condition after four years of use. Improvements to the lock design are needed before scale-up. Installation of screening in buildings should be accompanied with health messaging recommending that at night, doors and windows be closed and curtains lifted or drawn to one side - to improve ventilation and keep the house cool.

Pengobatan Malaria di Perkotaan dan Pedesaan di Indonesia (Analisis Lanjut Riskesdas 2013)

Malaria control in Indonesia still against many challenges, especially in terms of malaria treatment. One of the causes of low coverage of Artemisin Based Combination Therapy (ACT) is that several locations are no longer malaria endemic, being negligent with malaria cases coming from endemic areas, so that patients are not immediately diagnosed as malaria patients. The purpose of this further analysis was to describe malaria treatment based on Plasmodium species associated with access, time, and administration of ACT treatment between urban and rural areas. The method used is descriptive analysis of secondary data from Basic Health Research in 2013 as many as 1,027,763 people by taking the unit of analysis of individuals who have been diagnosed with malaria by health personnel and individuals whose blood test results are positive for malaria. The results of the analysis provide information that in urban and rural areas, the treatment of P. falciparum and P. vivax is classified as good, namely the majority received ACT treatment, the time to receive ACT treatment was within the first 24 hours, and ACT treatment was given within 3 days of being drunk. However, it was found that in rural areas, P. vivax treatment was still not good because the majority did not receive ACT treatment. The implementation of malaria control in areas that are easily accessible and well-targeted are groups that can afford the costs involved in accessing targeted interventions by public subsidized programs. This encourages all regions to have good health services that provide better access to malaria control interventions.

Regional Heterogeneity of Malaria Prevalence And Associated Risk Factors Among Children Under Five In Togo: Evidence From National Malaria Indicators Survey

Background: Malaria remains one of the main causes of morbidity and death among children less than 5. In Togo, despite intensification of malaria control interventions, persistence in malaria prevalence was observed and appears to vary from one region to another within the country. The aim of this study is to explore further regional heterogeneities in malaria prevalence and to determine associated risk factors.Methods: Data from the cross-sectional survey of the nationally representative 2017 Togo malaria indicator survey was used. Children aged 6–59 months in the selected households were tested for malaria using the rapid diagnostic test (RDT) and the microscopy. Univariate and multivariate logistic regression analysis were preformed using Generalized Linear Models.Results: A total of 3271 children under five (2441 in rural areas and 830 in urban areas was enrolled. Overall 26% of children tested positive for malaria, as confirmed by microscopy, ranging from 5.3% in the Lomé Commune region to 43.6% in the Plateaux region. In multivariate analysis, factors associated with malaria prevalence were living in the Plateaux region (aOR=4.24, 95%CI [2.38-7.65]), and the Maritime region (aOR=2.02, 95%CI [1.13-3.66], compared to Lomé Commune region); age 24 to 35 months (aOR=1.46, 95%CI [1.13-1.88) and age 36 to 59 months (aOR=2.5, 95%CI [2.04-3.09]) ], Compared to those age 6-23 months; households within the richest wealth quintile (a.OR=0.22, 95%CI [0.11-0.41], compared to poorest) and residence in rural areas (aOR=2.02, 95%CI [1.32-3.13], compared to resident in urban). Conclusion: Interventions that targeted use of combined prevention measures, adapted to older children living in rural areas and particularly in the regions of high malaria prevalence, could result in better malaria control in Togo.

P. Falciparum Community Prevalence and Health Seeking Behaviors in Rural Sussundenga District, Mozambique

Background: The large-scale effectiveness of malaria control interventions is differential at international border settings with varying policies, such as that between Mozambique and Zimbabwe. Impacts of nationally directed malaria control interventions hinge on understanding malaria transmission and prevention at the community level along international borders. Thus far, few studies have focused on central Mozambique. Our aim was to describe community level P. falciparum transmission dynamics and health seeking behaviors among residents of Sussundenga, Mozambique, a rural village bordering Zimbabwe in Manica Province with high malaria incidence reported at the Sussundenga-Sede health center (RHC). Methods: We conducted a cross-sectional community-based survey from December 2019 – February 2020. We used a random household sampling method, based on enumerated households from satellite imagery. All consenting participants completed a survey about malaria risk, prevention, and health seeking-behaviors, and received a P. falciparum malaria rapid diagnostic test (RDT). Results: We enrolled 96 households with 358 individuals. The P. falciparum prevalence was 31.6% (95% CI [26.6-36.5]). Ninety-three percent of participants reported using the Sussundenga-Sede RHC for healthcare. Sixty-six percent of participants (N=233) experienced at least one malaria symptom in the past month, with self-reported fever most frequently reported (19.3%). Of these, 176 (76.5%) sought care in a health facility and 174 (79%) received an RDT with 130 (63%) positive results. Of those with a positive RDT, 127 (97%) received Coartem®. Following treatment, 123 (97%) participants' symptoms resolved within a median of 3 days (IQR: 3-5) ranging from 2-14 days. In this high transmission setting, a high proportion of participants recognized malaria related symptoms then received a proper diagnostic test and treatment in a health facility. Conclusions: Future interventions that leverage this health seeking behavior and strengthen health systems for community interventions will improve malaria control and inform the efficacy of potential interventions at this particular international border.