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.

Prevention and control of dengue and Chikungunya in Colombia: A cost-effectiveness analysis

Background Chikungunya and dengue are emerging diseases that have caused large outbreaks in various regions of the world. Both are both spread by Aedes aegypti and Aedes albopictus mosquitos. We developed a dynamic transmission model of chikungunya and dengue, calibrated to data from Colombia (June 2014 –December 2017). Methodology/Principal findings We evaluated the health benefits and cost-effectiveness of residual insecticide treatment, long-lasting insecticide-treated nets, routine dengue vaccination for children aged 9, catchup vaccination for individuals aged 10–19 or 10–29, and portfolios of these interventions. Model calibration resulted in 300 realistic transmission parameters sets that produced close matches to disease-specific incidence and deaths. Insecticide was the preferred intervention and was cost-effective. Insecticide averted an estimated 95 chikungunya cases and 114 dengue cases per 100,000 people, 61 deaths, and 4,523 disability-adjusted life years (DALYs). In sensitivity analysis, strategies that included dengue vaccination were cost-effective only when the vaccine cost was 14% of the current price. Conclusions/Significance Insecticide to prevent chikungunya and dengue in Columbia could generate significant health benefits and be cost-effective. Because of limits on diagnostic accuracy and vaccine efficacy, the cost of dengue testing and vaccination must decrease dramatically for such vaccination to be cost-effective in Colombia. The vectors for chikungunya and dengue have recently spread to new regions, highlighting the importance of understanding the effectiveness and cost-effectiveness of policies aimed at preventing these diseases.

Development And Validation of An Eco-Friendly and High-Throughput HPLC Method To Quantify Pyrethroid and Pyriproxyfen in Long-Lasting Insecticide-Treated Nets

Long-lasting insecticide-treated nets (LLINs) are essential to preventing malaria transmission. The LLINs should last for at least three years, even after repeated washings. Currently, tracking insecticides in LLINs is cumbersome, costly, and requires specialized equipment and hazardous solvents. We therefore developed a low-resource, high-throughput method for detecting insecticides in LLINs. In order to extract insecticides from polyethylene, LLIN samples were heated for 45 minutes at 85oC in 1-propanol-heptane containing dicyclohexylphthalate as an internal standard. Sample size was reduced to ~0.2 g for reduced extraction volume, which is 10% less than what was recommended. We optimized HPLC chromatographic conditions to assess pyrethroid and pyriproxyfen content in polyethylene-based LLINs. The method is capable of quantifying levels ≥ 0.0015% permethrin, 0.00045% alpha-cypermethrin and 0.00025% pyriproxyfen (w/w) in polyethylene, allowing tracking the insecticides before and after LLINs use. A variety of LLINs can be evaluated with this method, including those with 1% pyriproxyfen (pyriproxyfen-LLIN) or 2% permethrin (Olyset® Net), 1% pyriproxyfen and 2% permethrin (Olyset® Duo), or 0.55% pyriproxyfen combined with 0.55% alpha-cypermethrin (Royal Gaurd®). Analysis of 120 samples (40 nets) per run can be done with high precision and accuracy, reducing labour time and costs whilst reducing the environmental impact of organic solvents.

Malaria Prevalence and Associated Factors among Pregnant Women Attending their First Antenatal Care in Kole and Kyenjojo Districts in Uganda

Malaria during pregnancy has negative consequences to both the mother and fetus. In 2019, there were an estimated 33million pregnancies globally, of which 35% were exposed to malaria in Africa. To avert the consequences, the Uganda Ministry of Health is implementing approaches for effective prevention with intermittent preventive treatment, use Insecticide-Treated Nets (ITN), prompt diagnosis, and treatment through antenatal care (ANC). This study was conducted to determine the prevalence of malaria and associated factors among pregnant women attending their first ANC visit in Kole and Kyenjojo Districts in Uganda. A cross-sectional study design was conducted among 760 randomly selected pregnant women. Quantitative data was collected using a structured questionnaire to gather participants’ demographic, obstetric, coverage, and use of malaria preventive methods and laboratory results on malaria, anaemia, and HIV. Data was analyzed using STATA 15. Chi-square, odds ratio, and logistic regression were used to test for associations. The overall prevalence of malaria was 11.1%, varying from 6.8% in Kyenjojo to 15.3% in Kole District. Most cases were caused by P. falciparum. Factors associated with malaria were age of mother (aOR: 0.44, 95% CI: 0.21-0.88), residence in Kyenjojo (aOR: 0.48, 95% CI: 0.26-0.88), multiparity (aOR: 0.38, 95% CI: 0.16-0.91), anaemia (aOR: 2.12, 95% CI: 1.12-4.00) and ITN non-use (aOR: 6.17, 95% CI: 2.76-13.86). Malaria prevalence was low and varied between districts. Age, gravidity, gestational age, and ITN use had a significant association with malaria. Therefore, early screening and identification of mothers at most risk of complications during pregnancy is needed, plus improving ANC.

Factors Associated with the Use of Insecticide-Treated Nets Among Women of Reproductive Age in Mozambique, 2018

Background: In 2018 there were approximately 228 million diagnosed cases of malaria and 405,000 deaths. The use of insecticide-treated nets (ITNs) is one of the main malaria prevention interventions. Despite widescale distribution resulting in improved ITN access, use remains an important challenge. This study determined factors associated with the use of ITNs among women of reproductive age in Mozambique in 2018.Methods: A secondary analysis of data from the 2018 Malaria Indicator Survey (MIS) was implemented. Women of reproductive age (15-49 years) from households with at least one ITN were included in the analysis. Appropriately weighted descriptive analysis of sociodemographic characteristics and univariate and multivariate logistic regression were performed to identify factors associated with ITN use. The highest frequency categories were used as reference variables for the variables age, province, type of place of residence and wealth quintile and the lowest frequency category was used for education level. Variables that had p-value <0.05 were considered statistically significant.Results: Of 6,184 total women of reproductive age in the MIS, 5,587 women (90%) were in households with at least one ITN, of whom 88% (4,908/5,587) reported prior night use of ITNs. Most women were in the 15-19 age group of whom 81% (975/1,206) reported ITN use. The odds of ITN use were significantly higher in all other age groups compared to these women aged 15-19 years. The odds of ITN use were significantly lower in lower prevalence provinces in southern Mozambique. In adjusted analysis, there was no significant association between the odds of ITN use and malaria knowledge, exposure to malaria messages, literacy, or other sociodemographic variables.Conclusions:. Young women and those in southern Mozambique are demographic groups that would benefit from targeted communication interventions, along with those in rural areas where the burden of malaria is higher.

Developing Consensus Standard Operating Procedures (SOPs) to Evaluate New Types of Insecticide-Treated Nets

In response to growing concerns over the sustained effectiveness of pyrethroid-only based control tools, new products are being developed and evaluated. Some examples of these are dual-active ingredient (AI) insecticide-treated nets (ITNs) which contain secondary insecticides, or synergist ITNs which contain insecticide synergist, both in combination with a pyrethroid. These net types are often termed ‘next-generation’ insecticide-treated nets. Several of these new types of ITNs are being evaluated in large-scale randomized control trials (RCTs) and pilot deployment schemes at a country level. However, no methods for measuring the biological durability of the AIs or synergists on these products are currently recommended. In this publication, we describe a pipeline used to collate and interrogate several different methods to produce a singular ‘consensus standard operating procedure (SOP)’, for monitoring the biological durability of three new types of ITNs: pyrethroid + piperonyl butoxide (PBO), pyrethroid + pyriproxyfen (PPF), and pyrethroid + chlorfenapyr (CFP). This process, convened under the auspices of the Innovation to Impact programme, sought to align methodologies used for conducting durability monitoring activities of next-generation ITNs.

Residual insecticide surface treatment for preventing malaria: a systematic review protocol

Introduction: Malaria presents a significant global public health burden, although substantial progress has been made, with vector control initiatives such as indoor residual surface spraying with insecticides and insecticide treated nets. There now exists many different approaches to apply residual insecticide to indoor and outdoor surfaces in malaria endemic settings. This review aims to synthesise the best available evidence regarding full or partial indoor or outdoor residual insecticide surface treatment for preventing malaria. Methods and Analysis: This review will comprehensively search the literature (both published and unpublished) for any studies investigating the effectiveness of residual insecticide surface treatment for malaria. Studies will be screened to meet the inclusion criteria by a minimum of two authors, followed by assessment of risk of bias (using appropriate risk of bias tools for randomised and non-randomised studies) and extraction of relevant information using structured forms by two independent authors. Meta-analysis will be carried out where possible for epidemiological outcomes such as malaria, anaemia, malaria related mortality, all-cause mortality and adverse effects. Certainty in the evidence will be established with GRADE assessments. Ethics and Dissemination: A full review report will be submitted to the Vector Control & Insecticide Resistance Unit, Global Malaria Program, WHO. A version of this report will be submitted for publication in an open access peer-reviewed journal. The report will inform the development of WHO recommendations regarding residual insecticide treatment for malaria. This systematic review does not require ethics approval as it is a review of primary studies. Registration: PROSPERO, ID 293194 (in progress as of 24th November, 2021)

Classifying Features Persuading the Use of Long Lasting Insecticide Treated Nets (LLINs) and Its Implications in Exterminating the Incidence of Malaria-Death in Ghana

This is a cross-sectional quantitative study purported to identify features deemed to persuade the usage of LLINs in exterminating incidences of malaria-death in Ghana. The population consisted of mothers and caregivers of children under five in Asamankese a district in the Eastern region of Ghana. Questionnaires were developed based on the profile and the set of study objectives, it sought information on socio-economic variables, knowledge level on LLINs, and influence of climatic and environmental factors on LLINs usage. Data were coded and keyed into SPSS version 20. Frequencies, percentages, means, standard deviations, graphs and tables were used to explore the data. Chi-square test was used to do further investigation. It was revealed that LLINs usage was influenced by a group of features including: background characteristics of household; socio-economic variables, environmental variables and knowledge on importance of LLINs. There was an association between LLINs usage and monthly income of caregivers (p<0.05). Furthermore, there was a significant relationship (p<0.05) between environmental features and LLINs usage. There was a relationship (p<0.05) between one’s knowledge and use of LLINs. In addition, there was a relationship between usage and the number of times per month visits were made to the hospitals for health care. Environmental factors permitted the use of LLINs, Eighty-six (86%) of the respondents who used LLINs did use it because the weather aided them. It is recommended that behavior change education be intensified in the region so that more people can accept and adopt a lifestyle that will protect them from the deadly malaria diseases. Efforts must be made by the major players in the health sector to make the net readily available in the communities at low prices to enable the ordinary Ghanaian to purchase it.

Recent trends in global insecticide use for disease vector control and potential implications for resistance management

Insecticides have played a major role in the prevention, control, and elimination of vector-borne diseases, but insecticide resistance threatens the efficacy of available vector control tools. A global survey was conducted to investigate vector control insecticide use from 2010 to 2019. Out of 140 countries selected as sample for the study, 87 countries responded. Also, data on ex-factory deliveries of insecticide-treated nets (ITNs) were analyzed. Insecticide operational use was highest for control of malaria, followed by dengue, leishmaniasis and Chagas disease. Vector control relied on few insecticide classes with pyrethroids the most used overall. Results indicated that IRS programs have been slow to react to detection of pyrethroid resistance, while proactive resistance management using insecticides with unrelated modes of action was generally weak. The intensive use of recently introduced insecticide products raised concern about product stewardship regarding the preservation of insecticide susceptibility in vector populations. Resistance management was weakest for control of dengue, leishmaniasis or Chagas disease. Therefore, it will be vital that vector control programs coordinate on insecticide procurement, planning, implementation, resistance monitoring, and capacity building. Moreover, increased consideration should be given to alternative vector control tools that prevent the development of insecticide resistance.

Assessing health-seeking behaviour and malaria prevention practices among communities in four districts of the Volta Region of Ghana

Background Malaria is a preventable disease that causes huge morbidity and mortality in malaria-endemic areas, especially among children and pregnant women. The malaria control programme focuses on the prevention of mosquito bites using insecticide-treated nets (ITNs) and mosquito aerosol sprays and coils, as well as prevention of severe disease among those infected through prompt and adequate treatment. The success of the malaria control programme in Ghana is dependent on the malaria prevention practices of people in the community. Therefore, this study evaluated the malaria prevention practices of participants in four districts of the Volta Region of Ghana. Methods This was a cross-sectional study conducted in Ketu South, Nkwanta South, Hohoe Municipality and Ho West districts of the Volta Region of Ghana. Questionnaire were administered to adults who consented to each household visited. Questions were asked on the socio-demographics and malaria prevention practices of the households. Data analysis was done using SPSS version 23 with frequency distribution done for all the variables. Pearson chi-square was used to determine the significant association between socio-demographics and malaria prevention practices, and Multivariate nominal logistic regression analysis was used to model the relationship between dichotomous dependent variables (ITN ownership and usage) and independent variables. Results Out of the 2493 participants; 2234 (89.6%) owned ITN and 1528 (68.4%) used ITN a night before this study, 768 (30.8%) used mosquito aerosol spray and 368 (15%) used mosquito coil. More females significantly owned ITN than males (1293, 92.4%, p ≤ 0.001). Participants from Ketu South had 1.5 times higher odds of owning an ITN compared to Ho West whose odds are not different from Nkwanta South or Hohoe (AOR, 1.56 [95% 1.09–2.22]; p = 0.01). In terms of ITN usage, participants in Nkwanta South were less likely to use ITN compared to the other districts; AOR, 0.434 [95% CI 0.31–0.62, p < 0.001]. Also, of the 668 participants that had a fever within the past 3 days, 268 (40.1%) visited a patent medicine store and 156 (23.4%) visited health facilities. Conclusion There is high ownership of ITNs, but relatively low utilization among the community members. Education on malaria prevention practices should be intensified and continuous among the population of the Volta Region to ensure the success of malaria control in the region.