Long-lasting Insecticide-treated Nets Research Articles

Asymptomatic Plasmodium falciparum malaria prevalence among adolescents and adults in Malawi, 2015\u20132016

Malaria remains a significant cause of morbidity and mortality in Malawi, with an estimated 18–19% prevalence of Plasmodium falciparum in children 2–10 years in 2015–2016. While children report the highest rates of clinical disease, adults are thought to be an important reservoir to sustained transmission due to persistent asymptomatic infection. The 2015–2016 Malawi Demographic and Health Survey was a nationally representative household survey which collected dried blood spots from 15,125 asymptomatic individuals ages 15–54 between October 2015 and February 2016. We performed quantitative polymerase chain reaction on 7,393 samples, detecting an overall P. falciparum prevalence of 31.1% (SE = 1.1). Most infections (55.6%) had parasitemias ≤ 10 parasites/µL. While 66.2% of individuals lived in a household that owned a bed net, only 36.6% reported sleeping under a long-lasting insecticide-treated net (LLIN) the previous night. Protective factors included urbanicity, greater wealth, higher education, and lower environmental temperatures. Living in a household with a bed net (prevalence difference 0.02, 95% CI − 0.02 to 0.05) and sleeping under an LLIN (0.01; − 0.02 to 0.04) were not protective against infection. Our findings demonstrate a higher parasite prevalence in adults than published estimates among children. Understanding the prevalence and distribution of asymptomatic infection is essential for targeted interventions.

The Impact of Renewing Long-Lasting Insecticide-Treated Nets in the Event of Malaria Resurgence: Lessons from 10 Years of Net Use in Dielmo, Senegal.

The occurrence of malaria resurgences could threaten progress toward elimination of the disease. This study investigated the impact of repeated renewal of long-lasting insecticide-treated net (LLIN) universal coverage on malaria resurgence over a period of 10 years of net implementation in Dielmo (Senegal). A longitudinal study was carried out in Dielmo between August 2007 and July 2018. In July 2008, LLINs were offered to all villagers through universal campaign distribution which was renewed in July 2011, August 2014, and May 2016. Malaria cases were treated with artemisinin-based combination therapy. Two resurgences of malaria occurred during the 10 years in which LLINs have been in use. Since the third renewal of the nets, malaria decreased significantly compared with the first year the nets were implemented (adjusted incidence rate ratio) (95% CI) = 0.35 (0.15-0.85), during the ninth year after net implementation). During the tenth year of net implementation, no cases of malaria were observed among the study population. The use of nets increased significantly after the third time the nets were renewed when compared with the year after the first and the second times the nets were renewed (P < 0.001). The third renewal of nets, which took place after 2 years instead of 3 years together with a higher use of LLINs especially among the young, probably prevented the occurrence of a third malaria upsurge in this village.

Protective effects of Olyset\xae Net on Plasmodium falciparum infection after three years of distribution in western Kenya

BackgroundSeveral types of insecticides, treating technologies and materials are available for long-lasting insecticide-treated nets (LLINs). The variations may result in different efficacies against mosquitoes and correspondingly infection risks for the Plasmodium falciparum malaria parasite. This cross-sectional study investigated whether infection risk varied among children who slept under different LLIN brands in rural villages of western Kenya.MethodsChildren sleeping under various types of LLINs were tested for P. falciparum infection using a diagnostic polymerase chain reaction (PCR) assay. Data were collected for other potential factors associated with infection risk: sleeping location (with bed/without bed), number of persons sharing the same net, dwelling wall material, gap of eaves (open/close), proportional hole index, socio-economic status, and density of indoor resting anophelines. Bed-net efficacy against the Anopheles gambiae susceptible strain was estimated using the WHO cone test and the tunnel test. The residual insecticide content on nets was measured.ResultsSeven LLIN brands were identified, and deltamethrin-based DawaPlus® 2.0 was the most popular (48%) followed by permethrin-based Olyset® Net (28%). The former LLIN was distributed in the area about six months before the present study was conducted, and the latter net was distributed at least three years before. Of 254 children analysed, P. falciparum PCR-positive prevalence was 58% for DawaPlus® 2.0 users and 38% for Olyset® users. The multiple regression analysis revealed that the difference was statistically significant (adjusted OR: 0.67, 95% credible interval: 0.45–0.97), whereas the confounders were not statistically important. Among randomly selected net samples, all DawaPlus® 2.0 (n = 20) and 95% of Olyset® (n = 19) passed either the cone test or the tunnel test.ConclusionsOlyset® was more effective in reducing infection risk compared with DawaPlus® 2.0. Although the data from the present study were too limited to explain the mechanism clearly, the results suggest that the characteristics of the former brand are more suitable for the conditions, such as vector species composition, of the study area.

Monitoring Plasmodium falciparum and Plasmodium vivax using microsatellite markers indicates limited changes in population structure after substantial transmission decline in Papua New Guinea.

Monitoring the genetic structure of pathogen populations may be an economical and sensitive approach to quantify the impact of control on transmission dynamics, highlighting the need for a better understanding of changes in population genetic parameters as transmission declines. Here we describe the first population genetic analysis of two major human malaria parasites, Plasmodium falciparum (Pf) and Plasmodium vivax (Pv), following nationwide distribution of long-lasting insecticide-treated nets (LLINs) in Papua New Guinea (PNG). Parasite isolates from pre- (2005-2006) and post-LLIN (2010-2014) were genotyped using microsatellite markers. Despite parasite prevalence declining substantially (East Sepik Province: Pf=54.9%-8.5%, Pv=35.7%-5.6%, Madang Province: Pf=38.0%-9.0%, Pv: 31.8%-19.7%), genetically diverse and intermixing parasite populations remained. Pf diversity declined modestly post-LLIN relative to pre-LLIN (East Sepik: Rs =7.1-6.4, HE =0.77-0.71; Madang: Rs =8.2-6.1, HE =0.79-0.71). Unexpectedly, population structure present in pre-LLIN populations was lost post-LLIN, suggesting that more frequent human movement between provinces may have contributed to higher gene flow. Pv prevalence initially declined but increased again in one province, yet diversity remained high throughout the study period (East Sepik: Rs =11.4-9.3, HE =0.83-0.80; Madang: Rs =12.2-14.5, HE =0.85-0.88). Although genetic differentiation values increased between provinces over time, no significant population structure was observed at any time point. For both species, a decline in multiple infections and increasing clonal transmission and significant multilocus linkage disequilibrium post-LLIN were positive indicators of impact on the parasite population using microsatellite markers. These parameters may be useful adjuncts to traditional epidemiological tools in the early stages of transmission reduction.

A Study of the Susceptibility of Anopheles species to Pyrethroids on Long Lasting Insecticide Treated Nets (LLINs) and Ownership and Usage of LLINs in Some Communities in Obi Local Government Area

The use of Long-Lasting Insecticide-treated Nets (LLINs) for Malaria vector control depends entirely on the continued susceptibility...

How useful are malaria risk maps at the country level? Perceptions of decision-makers in Kenya, Malawi and the Democratic Republic of Congo

BackgroundDeclining malaria prevalence and pressure on external funding have increased the need for efficiency in malaria control in sub-Saharan Africa (SSA). Modelled Plasmodium falciparum parasite rate (PfPR) maps are increasingly becoming available and provide information on the epidemiological situation of countries. However, how these maps are understood or used for national malaria planning is rarely explored. In this study, the practices and perceptions of national decision-makers on the utility of malaria risk maps, showing prevalence of parasitaemia or incidence of illness, was investigated.MethodsA document review of recent National Malaria Strategic Plans was combined with 64 in-depth interviews with stakeholders in Kenya, Malawi and the Democratic Republic of Congo (DRC). The document review focused on the type of epidemiological maps included and their use in prioritising and targeting interventions. Interviews (14 Kenya, 17 Malawi, 27 DRC, 6 global level) explored drivers of stakeholder perceptions of the utility, value and limitations of malaria risk maps.ResultsThree different types of maps were used to show malaria epidemiological strata: malaria prevalence using a PfPR modelled map (Kenya); malaria incidence using routine health system data (Malawi); and malaria prevalence using data from the most recent Demographic and Health Survey (DRC). In Kenya the map was used to target preventative interventions, including long-lasting insecticide-treated nets (LLINs) and intermittent preventive treatment in pregnancy (IPTp), whilst in Malawi and DRC the maps were used to target in-door residual spraying (IRS) and LLINs distributions in schools. Maps were also used for operational planning, supply quantification, financial justification and advocacy. Findings from the interviews suggested that decision-makers lacked trust in the modelled PfPR maps when based on only a few empirical data points (Malawi and DRC).ConclusionsMaps were generally used to identify areas with high prevalence in order to implement specific interventions. Despite the availability of national level modelled PfPR maps in all three countries, they were only used in one country. Perceived utility of malaria risk maps was associated with the epidemiological structure of the country and use was driven by perceived need, understanding (quality and relevance), ownership and trust in the data used to develop the maps.

Species diversity and distribution of Anopheles mosquitoes in Bure district, Northwestern Ethiopia

Malaria is one the leading health problem of the Ethiopia. Previously, areas above 2,000 m elevation were considered as malaria free areas. However, the major malaria epidemics were seen in areas at an altitude up to 3,000 m above sea level. These epidemics were due to climate and land-use changes (ecological changes) and still malaria is a growing health problem in highland parts of Ethiopia. This study aimed to investigate the species diversity, abundance and distribution of Anopheles mosquitoes in highland fringe of Bure district, Northwestern Ethiopia. It was done in the three different agroecological villages, Bukta (Irrigated), Workimdr (non-irrigated with few dry season breeding habitats) and Shnebekuma (non-irrigated with many dry season breeding habitats). Anopheles mosquitoes were collected by the Centers for Disease Control and Prevention Light Traps Catches, Pyrethrum Spray Catches, and Artificial Pit Shelters (APSs) from twenty-seven houses, thirty houses, and six APSs, respectively. Anopheles mosquitoes were identified morphologically to species using standard keys. Furthermore, molecular identification of Anopheles gambiae s.l was carried out using species-specific Polymerase Chain Reaction. Independent T-Test and One-way- ANOVA were employed to compare the mean mosquito's density between villages and species, indoor and outdoor host seeking mosquitoes. Descriptive statistic was used to calculate the proportion of each Anopheles species. Nine Anopheles mosquito species were identified in the study area which includes: Anopheles demeilloni, An. arabiensis, An. funestus group, An. coustani, An. squamosus, An. cinereus, An. pharoensis, An. rupicolus, and An. natalensis. Of the 4,703 Anopheles mosquitoes collected, An. demeilloni was the most prominent (50.7%, n = 2383) whereas An. rupicolus (0.03%, n = 3), and An. natalensis (0.02%, n = 1) were the least abundant. Higher mean density of Anopheles mosquitoes was collected from the non-irrigated village (2.395 ± 0.100) than irrigated (1.351 ± 0.109) (p = 0.001). In conclusion, three of the most important malaria vectors (An. arabiensis, An. funestus group and An. pharoensis) of Ethiopia were recorded in the study sites, especially the first two was found thought-out the year. Most of the Anopheles mosquitoes were collected from non-irrigated villages. Thus, breeding habitat management must be practiced throughout the year together with long-lasting insecticide-treated nets and insecticide residual sprays.

Managing intermittent preventive treatment of malaria in pregnancy challenges: an ethnographic study of two Ghanaian administrative regions

BackgroundMalaria in pregnancy (MiP) is an important public health problem across sub-Saharan Africa. The package of measures for its control in Ghana in the last 20 years include regular use of long-lasting insecticide-treated bed nets (LLINs), directly-observed administration (DOT) of intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) and prompt and effective case management of MiP. Unfortunately, Ghana like other sub-Saharan African countries did not achieve the reset Abuja targets of 100% of pregnant women having access to IPTp and 100% using LLINs by 2015.MethodsThis ethnographic study explored how healthcare managers dealt with existing MiP policy implementation challenges and the consequences on IPTp-SP uptake and access to maternal healthcare. The study collected date using non-participant observations, conversations, in-depth interviews and case studies in eight health facilities and 12 communities for 12 months in two Administrative regions in Ghana.ResultsHealthcare managers addressed frequent stock-outs of malaria programme drugs and supplies from the National Malaria Control Programme and delayed reimbursement from the NHIS, by instituting co-payment, rationing and prescribing drugs for women to buy from private pharmacies. This ensured that facilities had funds to pay creditors, purchase drugs and supplies for health service delivery. However, it affected their ability to enforce DOT and to monitor adherence to treatment. Women who could afford maternal healthcare and MiP services and those who had previously benefitted from such services were happy to access uninterrupted services. Women who could not maternal healthcare services resorted to visiting other sources of health care, delaying ANC and skipping scheduled ANC visits. Consequently, some clients did not receive the recommended 5 + doses of SP, others did not obtain LLINs early and some did not obtain treatment for MiP. Healthcare providers felt frustrated whenever they could not provide comprehensive care to women who could not afford comprehensive maternal and MiP care.ConclusionFor Ghana to achieve her goal of controlling MiP, the Ministry of Health and other supporting institutions need to ensure prompt reimbursement of funds, regular supply of programme drugs and medical supplies to public, faith-based and private health facilities.

Moving towards malaria elimination in southern Mozambique: Cost and cost-effectiveness of mass drug administration combined with intensified malaria control.

As new combinations of interventions aiming at interrupting malaria transmission are under evaluation, understanding the associated economic costs and benefits is critical for decision-making. This study assessed the economic cost and cost-effectiveness of the Magude project, a malaria elimination initiative implemented in a district in southern Mozambique (i.e. Magude) between August 2015-June 2018. This project piloted a combination of two mass drug administration (MDA) rounds per year for two consecutive years, annual rounds of universal indoor residual spraying (IRS) and a strengthened surveillance and response system on the back of universal long-lasting insecticide treated net (LLIN) coverage and routine case management implemented by the National Malaria Control Program (NMCP). Although local transmission was not interrupted, the project achieved large reductions in the burden of malaria in the target district. We collected weekly economic data, estimated costs from the project implementer perspective and assessed the incremental cost-effectiveness ratio (ICER) associated with the Magude project as compared to routine malaria control activities, the counterfactual. We estimated disability-adjusted life years (DALYs) for malaria cases and deaths and assessed the variation of the ICER over time to capture the marginal costs and effectiveness associated with subsequent phases of project implementation. We used deterministic and probabilistic sensitivity analyses to account for uncertainty and built an alternative scenario by assuming the implementation of the interventions from a governmental perspective. Economic costs are provided in constant US$2015. After three years, the Magude project averted a total of 3,171 DALYs at an incremental cost of $2.89 million and an average yearly cost of $20.7 per targeted person. At an average cost of $19.4 per person treated per MDA round, the social mobilization and distribution of door-to-door MDA contributed to 53% of overall resources employed, with personnel and logistics being the main cost drivers. The ICER improved over time as a result of decreasing costs and improved effectiveness. The overall ICER was $987 (CI95% 968-1,006) per DALY averted, which is below the standard cost-effectiveness (CE) threshold of $1,404/DALY averted, three times the gross domestic product (GDP) per capita of Mozambique, but above the threshold of interventions considered highly cost-effective (one time the GDP per capita or $468/DALY averted) and above the recently suggested thresholds based on the health opportunity cost ($537 purchasing power parity/ DALY averted). A significantly lower ICER was obtained in the implementation scenario from a governmental perspective ($441/DALY averted). Despite the initial high costs and volume of resources associated with its implementation, MDA in combination with other existing malaria control interventions, can be a cost-effective strategy to drastically reduce transmission in areas of low to moderate transmission in sub-Saharan Africa. However, further studies are needed to understand the capacity of the health system and financial affordability to scale up such strategies at regional or national level.

Effectiveness of a health education intervention on the use of long-lasting insecticidal nets for the prevention of malaria in pregnant women of Pakistan: a quasi-experimental study

BackgroundAbout one quarter of pregnant women in the population of Pakistan are using long-lasting insecticide-treated bed nets (LLINs) for prevention of malaria. Past research reported that adequate information and education would act as mediator to change behaviour among patients for prevention of malaria infection. The effective use of LLINs would contribute to reduction of disease burden caused by malaria. The aim of this study was to determine the effectiveness of health education on the adoption of LLINs among pregnant women living in Tharparkar, a remote district in Sindh Province, Pakistan.MethodsA quasi-experimental study design with control and intervention groups was conducted with 200 pregnant women (100 in each group). Women in the intervention group were provided with health education sessions on malaria for 12 weeks, while those in the control group obtained routine information from lady health workers (LHWs). Pre- and post-intervention assessment was done of knowledge about malaria and use of LLIN, which was statistically analysed using descriptive statistics and difference in difference (DID) multivariable regression analysis to test effectiveness of the intervention.ResultsBaseline was conducted with 200 pregnant women. Demographic characteristics were similar in both groups with slight differences in age, education, income, type of latrine, and source of drinking water. There were no significant differences between mean knowledge and use of LLINs scores between groups at baseline. However, the estimated DID value after the intervention was 4.170 (p < 0.01) and represents an increase in scores of knowledge in the intervention group compared to control. Similarly DID value of 3.360 (p < 0.05) showed an increase in use of LLINs score after the intervention which was significant, showing that the intervention had a positive effect.ConclusionsResults proved that health education could be an effective intervention for improving knowledge and usage of LLINs among pregnant women for the prevention of malaria. Such educational interventions have a positive potential to be implemented at larger scale by incorporating them into routine health sessions provided by health workers.

A mobile digital technology (Fionet™) to improve accuracy, completeness and timeliness of research data compared with a non-digital system in Kenya

The World Health Organization’s Global Malaria Program implemented a multi-country study to assess the entomological and epidemiological impact of long-lasting insecticide treated nets (LLINs) and indoor residual spray (IRS). Study activities included home visits to perform a LLIN survey and malaria testing of children in the household. In Kenya, Fionet™, a technology for automated malaria Rapid Diagnostic Test (mRDT) processing and interpretation at point-of-care, was evaluated against traditional paper-based methods and manual mRDT processing. Objective: To measure and compare the accuracy of diagnosis, completeness, and timeliness of data transmission between a digital mobile solution (Fionet™) and a paper-based system. Methodology: A randomised cluster sampling design of two cohorts: 1) an Active Infection Detection cohort, and 2) an Active Case Detection cohort was undertaken between November 2013 and April 2014. Community Health Workers (CHWs) visited rural households to: 1) measure malaria prevalence in children under the age of five using mRDTs, and 2) survey the use and physical status of LLINs in the household. Ten clusters were randomly assigned to Fionet™ to perform automated testing, interpretation, and survey data capture. Fionet™ transmitted all the tests and survey data to a cloud-based database. Results: A total of 1770 households were visited, 437 children tested, and 742 LLINs inspected. Fionet™ significantly improved the quality of data gathered; a two-fold increase in adherence to study protocols using Fionet™ resulted in more accurate data, data completeness was 10 times higher than with paper-based collection methods, and 87% of data were available in less than one day. Fionet™ significantly improved data quality and management, which enhanced the health system’s ability to meet the research objectives. This technology can help ensure accurate, complete, and timely availability of data. Future studies should incorporate mobile technologies such as Fionet™ to improve RDT based diagnostics of malaria and data quality.

Householders' perception about sustaining the useful life of long-lasting insecticide-treated nets in Ghana.

BackgroundThis article explores the multifaceted perceptions among householders about the care, efficacy and disposal of long-lasting insecticide-treated nets (LLINs), especially those regarding the end of the useful life of LLINs, and their implications for malaria control.MethodsWe used a cross-sectional qualitative design. Data were gathered in the Shai-Osudoku District in the Greater Accra Region of Ghana using focus group discussions and in-depth interviews. A thematic analysis technique was applied to analyse the data.ResultsFour findings emerged. First, participants were familiar with LLINs and the issues concerning the end of their useful life. However, the application of this knowledge was deficient. Second, characteristics of effectiveness (e.g. torn beyond repair) other than the age of a net determined the end of the useful life of LLINs. Third, social desirability and other social practices had positive and negative influences on perceptions about LLIN use and the end of their useful life. Fourth, repurposing of LLINs signified the end of their useful life.ConclusionsPolicies and strategies to position LLIN use as the leading resource for malaria control need to be innovative to accommodate the perceptions and practices of targeted households.

Behavioural plasticity of Anopheles coluzzii and Anopheles arabiensis undermines LLIN community protective effect in a Sudanese-savannah village in Burkina Faso

BackgroundDespite the overall major impact of long-lasting insecticide treated nets (LLINs) in eliciting individual and collective protection to malaria infections, some sub-Saharan countries, including Burkina Faso, still carry a disproportionately high share of the global malaria burden. This study aims to analyse the possible entomological bases of LLIN limited impact, focusing on a LLIN-protected village in the Plateau Central region of Burkina Faso.MethodsHuman landing catches (HLCs) were carried out in 2015 for 12 nights both indoors and outdoors at different time windows during the highest biting activity phase for Anopheles gambiae (s.l.). Collected specimens were morphologically and molecularly identified and processed for Plasmodium detection and L1014F insecticide-resistance allele genotyping.ResultsAlmost 2000 unfed An. gambiae (s.l.) (54% Anopheles coluzzii and 44% Anopheles arabiensis) females landing on human volunteers were collected, corresponding to a median number of 23.5 females/person/hour. No significant differences were observed in median numbers of mosquitoes collected indoors and outdoors, nor between sporozoite rates in An. coluzzii (6.1%) and An. arabiensis (5.5%). The estimated median hourly entomological inoculation rate (EIR) on volunteers was 1.4 infective bites/person/hour. Results do not show evidence of the biting peak during night hours typical for An. gambiae (s.l.) in the absence of bednet protection. The frequency of the L1014F resistant allele (n = 285) was 66% in An. coluzzii and 38% in An. arabiensis.ConclusionsThe observed biting rate and sporozoite rates are in line with the literature data available for An. gambiae (s.l.) in the same geographical area before LLIN implementation and highlight high levels of malaria transmission in the study village. Homogeneous biting rate throughout the night and lack of preference for indoor-biting activity, suggest the capacity of both An. coluzzii and An. arabiensis to adjust their host-seeking behaviour to bite humans despite bednet protection, accounting for the maintenance of high rates of mosquito infectivity and malaria transmission. These results, despite being limited to a local situation in Burkina Faso, represent a paradigmatic example of how high densities and behavioural plasticity in the vector populations may contribute to explaining the limited impact of LLINs on malaria transmission in holo-endemic Sudanese savannah areas in West Africa.

Resistance to insecticides in Anopheles gambiae complex in West Africa: A review of the current situation and the perspectives for malaria control

In West Africa, the Anopheles gambiae sensu lato (s.l.) complex mosquitoes are the main malaria vectors. Malaria control relies mainly on long-lasting insecticide-treated nets (LLINs) and to a lesser extent on indoor residual spray (IRS) of insecticides. Important progress has been made in terms of malaria morbidity and mortality in these past decades. Resistance to insecticides in An. gambiae s.l. was first attributed to their use in agriculture. Further, their use in public health increased selection pressure. Resistance has been recorded to the four main classes of insecticides used in public health in West Africa. However, the spread of insecticide resistance in West Africa is persistent due to the lack of management of resistance monitoring. Resistance to insecticides involves different mechanisms. Resistance to pyrethroids and organochlorines was caused by target modification such as some sodium channel mutations in addition to metabolic changes. Reduction of sensitivity to organophosphates and carbamates was caused by acetylcholinesterase mutations. Therefore, efforts should be made as quickly as possible to develop novel vector control techniques. Furthermore, it is also suggested to combine environmental, chemical, and biological management. In this review, we outline the insecticide resistance of Anopheles in West Africa and the current alternative tools for effective mosquito vector control.

Effect of deltamethrin‐incorporated nets on mobility and survivorship of Halyomorpha halys (Hemiptera: Pentatomidae) adults and nymphs in the laboratory

AbstractThe brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), is an invasive pest that attacks specialty and row crops in North America and Europe. There has been a concerted effort to reduce frequent broad‐spectrum insecticide applications made on vulnerable crops. One tool that has emerged recently is the use of long‐lasting insecticide‐treated nets (LLINs) as a killing agent. Here, we conducted bioassays to evaluate the effect of direct contact on deltamethrin‐impregnated LLINs on the behaviour and survivorship of H. halys nymphs and adults in the laboratory. Following exposure at three different durations (1.25, 4.25 or 7.25 min), vertical and horizontal mobility of adults and nymphs and the flight capacity of adults were recorded and compared with individuals that were not exposed (control). Exposure to LLINs reduced the horizontal distance and velocity and increased the angular velocity of adults only but reduced vertical mobility of adults and nymphs. Adult flights were not significantly affected by LLIN exposure. Mortality of adults and nymphs at 7‐day post‐exposure ranged from 73% to 77% regardless of exposure time. We discuss our findings within the context of the potential for and limitations of deploying LLINs in vulnerable crops to manage H. halys populations.

Long-Lasting Insecticide-Treated Nets: Assessment of the Awareness and Utilization of Them among Antenatal Clinic Attendees in Abakaliki, Southeast Nigeria.

Background The use of long-lasting insecticide-treated nets (LLITNs) is one of the effective strategies for the prevention of malaria, especially among pregnant women. Aim This study is aimed at assessing the awareness and utilization of LLITNs during pregnancy among antenatal clinic attendees at the Alex Ekwueme Federal University Teaching Hospital Abakaliki. Materials and Methods This was a cross-sectional study among antenatal attendees at the Alex Ekwueme Federal University Teaching Hospital Abakaliki, Ebonyi State. A semistructured questionnaire was used to obtain relevant information from the participants. Data analysis was done using SPSS version 20. Results The mean age of the women was 26.05 ± 5.76 years. About one-third (30%) of the respondents were nulliparous. Most of the respondents had at least a secondary education. More than ninety percent of the respondents had a good knowledge of malaria with 95.8% being aware of LLITNs. The main source of information was from hospitals (54.5%). The rate of utilization of LLITNs was 37.5%; however, consistent use was only reported by about a third of this proportion. The major reasons for not utilizing the nets include discomfort/heat and fear of the chemical content. Women with tertiary education were more likely to utilize mosquito nets during pregnancy compared with women with secondary or primary education. Women who live in rural areas (OR = 0.393 95% CI 0.602–0.073) were less likely to use LLITNs during pregnancy, while those who are aware of the aetiology of malaria (OR = 4.38 95% CI 0.983–19.591) were more likely to utilize LLITNs in pregnancy. Conclusion The level of awareness of LLITNs is high; however, its utilization was discouragingly low. Rural dwellers and those without appropriate knowledge of the aetiology of malaria were less likely to use LLITNs in pregnancy.

Malaria Outbreak Facilitated by Appearance of Vector-Breeding Sites after Heavy Rainfall and Inadequate Preventive Measures: Nwoya District, Northern Uganda, February-May 2018.

Background Malaria is a leading cause of morbidity and mortality in Uganda. In April 2018, malaria cases surged in Nwoya District, Northern Uganda, exceeding expected limits and thereby requiring epidemic response. We investigated this outbreak to estimate its magnitude, identify exposure factors for transmission, and recommend evidence-based control measures. Methods We defined a malaria case as onset of fever in a resident of Anaka subcounty, Koch Goma subcounty, and Nwoya Town Council, Nwoya District, with a positive rapid diagnostic test or microscopy for malaria from 1 February to 25 May 2018. We reviewed medical records in all health facilities of affected subcounties to find cases. In a case-control study, we compared exposure factors between case-persons and asymptomatic controls matched by age and village. We also conducted entomological assessments on vector density and behavior. Results We identified 3,879 case-persons (attack rate [AR] = 6.5%) and two deaths (case-fatality rate = 5.2/10,000). Females (AR = 8.1%) were more affected than males (AR = 4.7%) (p < 0.0001). Of all age groups, 5–18 years (AR = 8.4%) were most affected. Heavy rain started in early March 2018, and a propagated outbreak followed in the first week of April 2018. In the case-control study, 55% (59/107) of case-persons and 18% (19/107) of controls had stagnant water around households for several days following rainfall (ORM-H = 5.6, 95% CI = 3.0–11); 25% (27/107) of case-persons and 51% (55/107) of controls wore full extremity covering clothes during evening hours (ORM-H = 0.30, 95% CI = 0.20–0.60); 71% (76/107) of case-persons and 85% (91/107) of controls slept under a long-lasting insecticide-treated net (LLIN) 14 days before symptom onset (ORM-H = 0.43, 95% CI = 0.22–0.85); 37% (40/107) of case-persons and 52% (56/107) of controls had access to at least one LLIN per 2 household members (ORM-H = 0.54, 95% CI = 0.30–0.97). Entomological assessment indicated active breeding sites in the entire study area; Anopheles gambiae sensu lato species were the predominant vector. Conclusion Increased vector-breeding sites after heavy rainfall and inadequate malaria preventive measures were found to have contributed to this outbreak. We recommended increasing coverage for LLINs and larviciding breeding sites in the area.

Use of alternative bioassays to explore the impact of pyrethroid resistance on LLIN efficacy

BackgroundThere is substantial concern that the spread of insecticide resistance will render long-lasting insecticide-treated nets (LLINs) ineffective. However, there is limited evidence supporting a clear association between insecticide resistance and malaria incidence or prevalence in the field. We suggest that one reason for this disconnect is that the standard WHO assays used in surveillance to classify mosquito populations as resistant are not designed to determine how resistance might impact LLIN efficacy. The standard assays expose young, unfed female mosquitoes to a diagnostic insecticide dose in a single, forced exposure, whereas in the field, mosquitoes vary in their age, blood-feeding status, and the frequency or intensity of LLIN exposure. These more realistic conditions could ultimately impact the capacity of “resistant” mosquitoes to transmit malaria.MethodsHere, we test this hypothesis using two different assays that allow female mosquitoes to contact a LLIN as they host-seek and blood-feed. We quantified mortality after both single and multiple exposures, using seven different strains of Anopheles ranging in pyrethroid resistance intensity.ResultsWe found that strains classified as 1×-resistant to the pyrethroid insecticide deltamethrin in the standard WHO assay exhibited > 90% mortality over 24 h following more realistic LLIN contact. Mosquitoes that were able to blood-feed had increased survival compared to their unfed counterparts, but none of the 1×-resistant strains survived for 12 days post-exposure (the typical period for malaria parasite development within the mosquito). Mosquitoes that were 5×- and 10×-resistant (i.e. moderate or high intensity resistance based on the WHO assays) survived a single LLIN exposure well. However, only about 2–3% of these mosquitoes survived multiple exposures over the course of 12 days and successfully blood-fed during the last exposure.ConclusionsThese results suggest that the standard assays provide limited insight into how resistance might impact LLIN efficacy. In our laboratory setting, there appears little functional consequence of 1×-resistance and even mosquitoes with moderate (5×) or high (10×) intensity resistance can suffer substantial reduction in transmission potential. Monitoring efforts should focus on better characterizing intensity of resistance to inform resistance management strategies and prioritize deployment of next generation vector control products.

Indications for blood and blood products transfusions among children in a semi-urban tertiary hospital in Nigeria

Background: Anaemia is prevalent among children in our environment, often necessitating blood transfusions. The knowledge of the common indications for blood transfusion and the required preventive measures is likely to reduce the transfusion rates. Objective: To determine the disease conditions requiring blood transfusion in post-neonatal age children at the Olabisi Onabanjo University Teaching Hospital, Sagamu, Nigeria. Methods: The hospital records of all children aged 1 month to 18 years admitted into the post-neonatal ward who received blood transfusions over 18 months (1st July 2015to­31st December 2016) were reviewed. Results: There were 710 paediatric admissions out of which 82 (11.6%) received blood transfusions. Ninety transfusions were carried out amongst 82 children, at a ratio of 1.1 transfusions per child. Severe malaria (28.1%), sickle cell anaemia (19.5%) and septicaemia (18.3) were the most common disease conditions requiring blood transfusions. The leading blood products transfused included packed red cells (64.5%) and whole blood (30.0%). Conclusion: Blood transfusion is frequently indicated in the paediatric population in our setting, largely due to severe malaria and sickle cell anaemia problems. Intensifying efforts on the use of long-lasting insecticide-treated nets and environmental control may reduce the prevalence of severe malaria, while improved nutrition, adequate hydration, regular malaria prophylaxis, prompt treatment of infections and regular use of haematinics may minimize the need for blood transfusions among children with sickle cell anaemia.

Creating mosquito-free outdoor spaces using transfluthrin-treated chairs and ribbons

BackgroundResidents of malaria-endemic communities spend several hours outdoors performing different activities, e.g. cooking, story-telling or eating, thereby exposing themselves to potentially-infectious mosquitoes. This compromises effectiveness of indoor interventions, notably long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS). This study characterized common peri-domestic spaces in rural south-eastern Tanzania, and assessed protective efficacy against mosquitoes of hessian fabric mats and ribbons treated with the spatial repellent, transfluthrin, and fitted to chairs and outdoor kitchens, respectively.MethodsTwo hundred households were surveyed, and their most-used peri-domestic spaces physically characterized. Protective efficacies of locally-made transfluthrin-emanating chairs and hessian ribbons were tested in outdoor environments of 28 households in dry and wet seasons, using volunteer-occupied exposure-free double net traps. CDC light traps were used to estimate host-seeking mosquito densities within open-structure outdoor kitchens. Field-collected Anopheles arabiensis and Anopheles funestus mosquitoes were exposed underneath the chairs to estimate 24 h-mortality. Finally, The World Health Organization insecticide susceptibility tests were conducted on wild-caught Anopheles from the villages.ResultsApproximately half (52%) of houses had verandas. Aside from these verandas, most houses also had peri-domestic spaces where residents stayed most times (67% of houses with verandas and 94% of non-veranda houses). Two-thirds of these spaces were sited under trees, and only one third (34.4%) were built-up. The outdoor structures were usually makeshift kitchens having roofs and partial walls. Transfluthrin-treated chairs reduced outdoor-biting An. arabiensis densities by 70–85%, while transfluthrin-treated hessian ribbons fitted to the outdoor kitchens caused 77–81% reduction in the general peri-domestic area. Almost all the field-collected An. arabiensis (99.4%) and An. funestus (100%) exposed under transfluthrin-treated chairs died. The An. arabiensis were susceptible to non-pyrethroids (pirimiphos methyl and bendiocarb), but resistant to pyrethroids commonly used on LLINs (deltamethrin and permethrin).ConclusionMost houses had actively-used peri-domestic outdoor spaces where exposure to mosquitoes occurred. The transfluthrin-treated chairs and ribbons reduced outdoor-biting malaria vectors in these peri-domestic spaces, and also elicited significant mortality among pyrethroid-resistant field-caught malaria vectors. These two new prototype formats for transfluthrin emanators, if developed further, may constitute new options for complementing LLINs and IRS with outdoor protection against malaria and other mosquito-borne pathogens in areas where peri-domestic human activities are common.