Long-lasting Insecticide-treated Bed Nets Research Articles

The Biodiversity of Anopheles and Malaria Vector Control in Indonesia: A Review

Malaria is a re-emerging vector-borne disease. Malaria is caused by Plasmodium parasites namely P. falciparum, P. malariae, P. vivax, P. ovale, and P. knowlesi. The parasite is transmitted by mosquitoes from the genus Anopheles. The genus Anopheles comprises more than 480 described species worldwide and many more are yet to be described. It is known that there are more than 100 species of Anopheles that can transmit malaria parasites to humans. The present review aims to assess studies on the biodiversity of Anopheles as a malaria vector and its control in Indonesia. The results showed that a total of 80 species of Anopheles mosquitos are reported in Indonesia, and at least 31 species of Anopheles mosquitoes have been reported as malaria vectors in Indonesia. Several efforts to decrease the number of malaria cases are the distribution and wide-scale use of Long-Lasting Insecticide Treated Bednets (LLIN), Indoor Residual Spraying (IRS) applications, larvae control, and environmental management. Vector control and entomological surveillance of malaria are one of the main domains for achieving malaria elimination. In conclusion, a combination of national policies, local-specific, habitat-specific, and community participation approaches are needed for effective malaria vector control in Indonesia.

Malaria Prevalence and Macroeconomic Output in Ghana, 1990 to 2019.

In Ghana, malaria remains the number 1 reason for outpatient department visits, making it a major public health problem. Thus, there could be significant lost productivity days as a result of malaria morbidity and mortality, which could negatively affect economic output at the macrolevel. Nonetheless, there is a dearth of empirical evidence of the effect of malaria on macroeconomic output in Ghana. This study therefore aims to provide the foremost empirical evidence regarding the effect of malaria prevalence on macroeconomic output in Ghana using a time series design with data spanning the period 1990 to 2019. Gross Domestic Product (GDP), serving as a proxy for macroeconomic output, is the dependent variable, while the prevalence of malaria (overall, among only males and among only females) serves as the main independent variable. The Ordinary Least Square (OLS) regression is used as the baseline estimation technique and the Instrumental Variable Two-Stage Least Square (IV2SLS) regression is employed as the robustness check estimator due to its ability to deal with endogeneity. The IV2SLS regression results show that a percentage increase in the overall prevalence of malaria is associated with a 1.16% decrease in macroeconomic output at 1% significance level. We also find that the effect of malaria in males on macroeconomic output is slightly higher relative to females. The findings from the OLS regression are not qualitatively different from the IV2SLS regression estimates. There is therefore the need to strengthen efforts such as quality case management, larval source management, mass distribution of long-lasting insecticide-treated bed nets, social behavior change, surveillance (both epidemiological and entomological), intermittent preventive treatment of malaria in pregnancy, research among others, which are important toward eliminating malaria.

Situational Analysis of Malaria Control Following the 2021 Distribution of Long Lasting Insecticide-Treated Bed Nets in the Tiko Health District, South West Region, Cameroon

Malaria is still a major public health concern in Cameroon as more than 20 million people are at risk of the disease. Despite the government’s effort to scale up the distribution of long lasting insecticide-treated bed nets (LLINs), full ownership and optimal use is still limited. In 2021, over a million LLINs were made available for distribution in the South West Region. However, the current situation of malaria has not yet been ascertained following the 2021 mass distribution campaign (MDC). Therefore, the aim of this study was to determine LLIN ownership, coverage, usage and the prevalence of malaria following the 2021 MDC in the Tiko Health District (THD), South West Region of Cameroon. A cross-sectional study was carried from May 1 to 27, 2022 in which a multi-stage sampling technique was used to enroll eligible participants. Data were collected from household heads using questionnaires and capillary blood samples collected from consented household members were used to test for malaria. Data were analyzed using SPSS version 25 at 0.05 significance level. From the 150 households surveyed, 96 (64.0%) owned a mosquito net before the recent MDC. There was an overall significant increase (p p = 0.644) in LLINs ownership between areas where door-to-door (79.5%) and fixed “Hit and Run” (75.8%) strategies were used in the distribution of LLINs in THD. The prevalence of malaria was 10.2%. The regular use of LLINs was significantly associated (p = 0.007) with low malaria prevalence. The 2021 MDC had an impact on malaria prevalence in those who properly used them.

Malawi ICEMR Malaria Research: Interactions and Results Influencing Health Policies and Practices.

Malaria remains a threat to public health in Malawi. It is well acknowledged that malaria research and robust evidence can have an impact on malaria policy and practice, resulting in positive population health gains. We report policy-relevant research contributions that the Malawi International Center of Excellence for Malaria Research (ICEMR) in partnership with local and international collaborators has made. Findings from our ICEMR studies have shown that long-lasting insecticide-treated bed nets (LLINs) impregnated with piperonyl butoxide reduced mosquito blood feeding more compared with conventional LLINs. On the other hand, we showed that few LLINs are maintained up to the end of their 3-year life span, and that older nets are less effective. These results support the policy change decisions by the Malawi National Malaria Control Program to switch from conventional LLINs to piperonyl butoxide LLINs, and to conduct mass LLIN distribution campaigns every 2 years. Our studies on epidemiological patterns of malaria infection showed that school-age children have higher malaria infection rates and lower use of control measures compared with younger children and adults. These findings added to the evidence base that influenced the National Malaria Control Program to endorse school-based malaria interventions as part of its national policy. Research supported by the Malawi ICEMR is contributing to in-country policy decisions and to the implementation of evidence-based interventions. Through our long-term studies we intend to continue providing practical and policy-relevant evidence necessary, ultimately, to eliminate malaria infection in Malawi.

Evidence-Based Malaria Control and Elimination in the Amazon: Input from the International Center of Excellence in Malaria Research Network in Peru and Brazil.

Malaria remains endemic in 17 countries in the Americas, where 723,000 cases were reported in 2019. The majority (> 90%) of the regional malaria burden is found within the Amazon Basin, which includes nine countries and territories in South America. Locally generated evidence is critical to provide information to public health decision makers upon which the design of efficient and regionally directed malaria control and elimination programs can be built. Plasmodium vivax is the predominant malaria parasite in the Amazon Basin. This parasite species appears to be more resilient to malaria control strategies worldwide. Asymptomatic Plasmodium infections constitute a potentially infectious reservoir that is typically missed by routine microscopy-based surveillance and often remains untreated. The primary Amazonian malaria vector, Nyssorhynchus (formerly Anopheles) darlingi, has changed its behavior to feed and rest predominantly outdoors, reducing the efficiency of core vector control measures such as indoor residual spraying and distribution of long-lasting insecticide-treated bed nets. We review public health implications of recent field-based research carried out by the Amazonia International Center of Excellence in Malaria Research in Peru and Brazil. We discuss the relative role of traditional and novel tools and strategies for better malaria control and elimination across the Amazon, including improved diagnostic methods, new anti-relapse medicines, and biological larvicides, and emphasize the need to integrate research and public health policymaking.

A Decade of Progress Accelerating Malaria Control in Mali: Evidence from the West Africa International Center of Excellence for Malaria Research.

This article highlights over a decade of signature achievements by the West Africa International Centers for Excellence in Malaria Research (WA-ICEMR) and its partners toward guiding malaria prevention and control strategies. Since 2010, the WA-ICEMR has performed longitudinal studies to monitor and assess malaria control interventions with respect to space-time patterns, vector transmission indicators, and drug resistance markers. These activities were facilitated and supported by the Mali National Malaria Control Program. Research activities included large-scale active and passive surveillance and expanded coverage of universal long-lasting insecticide-treated bed nets and seasonal malaria chemoprevention (SMC). The findings revealed substantial declines in malaria occurrence after the scale-up of control interventions in WA-ICEMR study sites. WA-ICEMR studies showed that SMC using sulfadoxine-pyrimethamine plus amodiaquine was highly effective in preventing malaria among children under 5 years of age. An alternative SMC regimen (dihydroartemisinin plus piperaquine) was shown to be potentially more effective and provided advantages for acceptability and compliance over the standard SMC regimen. Other findings discussed in this article include higher observed multiplicity of infection rates for malaria in historically high-endemic areas, continued antimalarial drug sensitivity to Plasmodium falciparum, high outdoor malaria transmission rates, and increased insecticide resistance over the past decade. The progress achieved by the WA-ICEMR and its partners highlights the critical need for maintaining current malaria control interventions while developing novel strategies to disrupt malaria transmission. Enhanced evaluation of these strategies through research partnerships is particularly needed in the wake of reported artemisinin resistance in Southeast Asia and East Africa.

Differential impact of environment on malaria due to control interventions in Uganda, 2010-2018

Background and aim Studies have estimated the impact of environment on malaria incidence although few have explored the differential impact due to vector control interventions. We aimed to evaluate the influence of temperature, rainfall, humidity, and vegetation, in presence or absence of long-lasting insecticide treated bednets (LLIN) and indoor residual spraying (IRS). Methods This study used weekly malaria cases from 2010 to 2018 from six health facility-based malaria surveillance in Uganda. Environmental variables were extracted from remote sensing sources and include enhanced vegetation index (MODIS), cumulative rainfall (ARC2), minimum and maximum temperature (ERA5), specific humidity (ERA5), averaged over different time periods (one to four months). Non-linearity of environmental variables was investigated, and general linear models based on a negative binomial distribution was used to explore the influence of ITN and LLIN on the malaria-environment relationship. Results A total of 204,252 malaria cases were laboratory confirmed and the median (range) weekly cases was 58.0 (0-597), rainfall 18.6 mm (0-129), minimum temperature 17.6˚C (12.3-24.2), maximum temperature 26.7˚C (20.1-34.8), and humidity 0.014 kg.kg (0.006-0.018). The best fit model was with the meteorological measures averaged over 3 months. All environmental variables showed a relatively linear pattern. Both IRS and LLIN were significantly associated with risk reduction (IRR: 0.39, 95% CI: 0.36–0.42 ; IRR: 0.71, 95% CI: 0.67–0.75, respectively). Marginal effects of environmental variables showed that joint effect of IRS and LLIN reduced the weekly predicted counts of malaria by 72.5% compared to no intervention. Conclusion LLIN and IRS both reduced the influence of environmental drivers of malaria and therefore morbidity in various transmission setting in Uganda. The benefits appeared to be greatest when the two interventions are used in combination.

Genetic identity, human blood indices, and sporozoite rates of malaria vectors in Gaa-Bolorunduro, Kwara State, Nigeria.

To identify the specific Anopheles mosquito sibling species responsible for malaria transmission, determine their vectorial potential, and predict suitable control measures, this study investigated genetic identities, human blood feeding, and sporozoite infection rates of endophilic Anopheles mosquitoes in Gaa-Bolorunduro, a cattle rearing community in Kwara State, Nigeria. Monthly pyrethrum spray collections of Anopheles mosquitoes were conducted for one year in addition to PCR characterization of sibling species and ELISA probing of human blood meal and sporozoite infections. Mean numbers and human blood indices (HBI) of the different Anopheles sibling species identified were compared. The total of 668 PCR-identified mosquitoes comprised 50.8% An. arabiensis, 46.7% An. gambiae, and 2.5% An. coluzzii. Annual mean numbers of An. arabiensis was significantly higher (p = 0.001) than An. coluzzii but not An. gambiae (p = 0.602). Proportions of An. arabiensis found with human blood (0.29) were lower compared to An. gambiae (0.72) and An. coluzzii (0.75). However, the annual mean HBI of An. arabiensis was not significantly higher than An. gambiae (p = 0.195) and An. coluzzii (p = 0.249). Plasmodium falciparum sporozoite infection rate was 1.6% in An. gambiae, 0.9% in An. arabiensis and 0% in An. coluzzii. The prevalent An. arabiensis and An. gambiae mosquitoes found indoors, despite the outdoor cattle population barrier, could be targeted by community-scale utilization of long-lasting insecticide-treated bed nets. Further studies on outdoor mosquito surveillance and bovine blood meal identification are required for the recommendation of suitable complementary vector control measures for the community.

Remote bednet use monitoring to describe patterns of use and exposure to female Anopheles mosquitoes in an Ugandan cohort.

Long lasting insecticide-treated bednets (LLINs) are the most widely used tool for preventing malaria. There has been a plateau in progress in the highest burden African countries since 2015, leading to questions about the effectiveness of LLINs. In this study, remote LLIN use monitors were deployed in a cohort in Eastern Uganda to explore how LLIN use interacts with mosquito exposure. The SmartNet study included 20 households from May to October 2019. SmartNet devices recorded, every 15 min, whether an LLIN was unfurled or folded up. Unannounced visits were used to assess SmartNet accuracy. Risk factors associated with poor LLIN use were assessed using generalized linear equations. Female Anopheles exposure was estimated by combining hourly probabilities of exposure from human landing catches and measures of density from biweekly CDC light traps in participants rooms. Mosquito exposure averted by LLINs was quantified using SmartNet measurements and age-related differences were estimated using generalized linear equations, adjusting for relevant covariates and household clustering. 96 individuals contributed 5,640 SmartNet observation nights. In 126 unannounced visits, SmartNet had an area under the curve of 0.869 in classifying whether the LLIN was up or down. The rate of non-use was 13.5% of nights (95% CI: 12.6-14.3%). Compared to children under 5, non-use was 1.8 times higher (95% CI: 1.6-2.1; p < 0.001) in children 5-15 years and 2.6 times higher (95% CI: 2.2-3.1; p < 0.001) in participants aged 15-<30years. There was no difference between children under 5 years and adults > 30 years. LLIN use averted 50.3% of female Anopheles mosquito exposure (95% CI: 40.0-60.0%), with decreasing point estimates of efficacy across age groups: from 61.7% (95% CI: 42.6-80.7%) in children under 5 years to 48.0% (95% CI: 29.1-66.8%) in adults over 30. Objective monitors are accurate and can feasibly be deployed to obtain data about LLIN use. LLINs provided protection from only 50% of female Anopheles mosquito exposure in this cohort and protection was dependent upon age. In assessing the role of LLINs in malaria prevention it is crucial to consider the dynamics between mosquito exposure and LLIN use behaviors.

Ecological and seasonal variations and other factors associated with clinical malaria in the Central Region of Ghana: A cross-sectional study

BackgroundThis study investigated malaria transmission under various contrasting settings in the Central Region, a malaria endemic region in Ghana. MethodsThis cross-sectional study was carried out in five randomly selected districts in the Central Region of Ghana. Three of the districts were forested, while the rest was coastal. Study participants were selected to coincide with either the regular rainy or dry season. From each study site, hospital attendees were randomly selected with prior consent. Consciously, study participants were selected in both rainy (September and October, 2020) and dry (November and December, 2020) seasons. Clinical data for each patient was checked for clinical malaria suspicion and microscopic confirmation of malaria. Using SPSS Version 24 (Chicago, IL, USA), bivariate analysis was done to determine the association of independent variables (ecological and seasonal variations) with malaria status. When the overall analysis did not yield significant association, further statistical analysis was performed after stratification of variables (into age and gender) to determine whether any or both of them would significantly associate with the dependent variable. ResultsOf the 3993 study participants, 62.5% were suspected of malaria whereas 38.2% were confirmed to have clinical falciparum malaria. Data analysis revealed that in both rainy and dry seasons, malaria cases were significantly higher in forested districts ) than coastal districts (x2 = 217.9 vs x2 = 50.9; p < 0.001). Taken together, the risk of malaria was significantly higher in the dry season (COR = 1.471, p < 0.001) and lower in coastal zones (COR = 0.826, p = 0.007). There was significant reduced risk of participants aged over 39 years of malaria (COR=0.657, p < 0.001). Whereas, in general patients between 10 and 19 years were insignificantly less likely to have malaria (COR = 0.911, p = 0.518) compared to participants aged less than< 10 years, the reverse was observed in coastal districts where patients less than 10 years of age in coastal districts were less likely to have malaria (COR=2.440, p = 0.003). In general, gender did not associate with malaria, but when stratified by study district, the risk of female gender to malaria was significantly higher in Agona Swedru (COR = 5.605, p < 0.001), Assin central (COR = 2.172, p < 0.001), Awutu Senya (COR = 2.410, p < 0.001) and Cape Coast (COR = 3.939, p < 0.001) compared to Abura-Asebu-Kwamankese. ConclusionThis study demonstrated that the predictors of malaria differ from one endemic area to another. Therefore, malaria control interventions such as distribution of long-lasting insecticide treated bed nets, residual spraying with insecticide and mass distribution of antimalaria prophylaxis must be intensified in forested districts in all seasons with particular attention on females.

Prevalence of Malaria and the Use of Long-lasting Insecticide Treated Bed Nets in Households of Rural and Semi-urban Communities in Mbengwi Health District, North West Region, Cameroon

Aims: In Cameroon, on August 2011 and October 2015 the Ministry of Public Health launched the national campaign for distribution of long-lasting insecticide-treated bed nets (LLINs) to all families as a means of effectively fighting malaria transmission. The study area Mbengwi Health District found in the North West Region of Cameroon benefitted from this distribution of LLINs, but the impact of this intervention has not been evaluated. This study was designed to assess the use of LLINs in selected households of rural and semi-urban communities in Mbengwi Health District.&#x0D; Study Design: A cross sectional study was conducted in households, between July 2017 to September 2017 in Mbengwi health district.&#x0D; Methodology: Two questionnaires were administered; one to the household head and the other to the occupants. Blood samples were obtained to diagnose and quantify malaria parasite and to determine hemoglobin concentrations (HB). A total of 93 households and 440 inhabitants of all sexes and age groups were surveyed.&#x0D; Results: Of the 440 participants, 49 were positive for malaria parasite giving an overall prevalence of 11.1%. From the questionnaires it was observed that 87 (93.5%) of the households owned LLINs, with up to 82 (94.3%) sleeping under the nets. All the owners of LLINs (87; 100%) obtained the nets from the government free of charge. There was no significant difference in bed-net ownership (p=0.978) and usage (p=0.664) between the rural and semi-urban communities. Malaria prevalence was significantly lower among users of LLINs (4.8%) than non-users (23.5%, p&lt;0.001). Malaria parasite density negatively correlated significantly with HB (r= -0.097, p=0.041).&#x0D; Conclusion: Overall, there was a high degree ownership and usage of LLINs by households in both rural and semi-urban communities, which was associated with protection from malaria infection.

Cross-sectional survey of asymptomatic malaria in Dak Nong province in the Central Highlands of Vietnam for the malaria elimination roadmap.

Asymptomatic parasite carriers represent a “silent” infective reservoir for malaria transmission and contributes to malaria persistence. However, limited data are available on asymptomatic malaria in Vietnam. Between November 2018 and March 2019, we conducted a malaria epidemiological survey of asymptomatic people (children ≥ 10 years old and adults ≥18 years old, n = 2,809) residing in three communes in Tuy Duc district, Dak Nong province in the Central Highlands of Vietnam. Based on the national stratification of malaria risk, Dak Buk So, Dak Ngo and Quang Truc communes were classified by the National Malaria Control Programme as low, moderate and high malaria endemic areas, respectively. Using participants’ finger prick blood samples, malaria parasites were detected by one-step reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The median age (Interquartile Range) for adults and children were 35 years (26–50) and 12 years (11–14), respectively. The prevalence of asymptomatic malaria was 1.7% (22/1,328), 3.5% (31/890) and 12.2% (72/591) for participants from Dak Buk So, Dak Ngo and Quang Truc, respectively. The prevalence of asymptomatic malaria was lower in children compared to adults: 2.6% (9/352) versus 4.7% (116/2,457) (Odds Ratio 0.53, 95% Confidence Interval 0.28 to1.02). Ownership of long-lasting insecticide-treated bed nets and hammocks was 97.1%, 99.0% and 94.7% for participants in Dak Buk So, Dak Ngo and Quang Truc, respectively, however, only 66.0%, 57.3% and 42.8% of the participants reported using bed nets every night. Of the several risk factors examined, going to the forest two weeks prior to enrolment into the study and sleeping in the forest had a significant association with participants being infected with asymptomatic malaria in Quang Truc, but not in the other two communes. Knowledge of the prevalence and distribution of asymptomatic malaria will help design and evaluate future intervention strategies for malaria elimination in Vietnam.

La revue systématique et autres types de revue de la littérature : qu’est-ce que c’est, quand, comment, pourquoi ?

Malaria is difficult to control in central India because of geographical terrain, efficient vectors, and perennial transmission of Plasmodium falciparum and socio-cultural practices of ethnic tribes. The objective was to develop a model to prevent and control malaria in hard to reach areas using existing tools. Baigachak (Tribe population 31,900) situated in Dindori district was undertaken for this study. Intervention measures used are indoor residual spray (IRS), long lasting insecticide treated bed nets (LLINs), prompt diagnosis and treatment along with intensive Information, Education and Communication (IEC) involving school children as agent of change. Door to door rapid fever surveys were carried out in the study area from 2009 to 14 and finger prick blood smears were made from all fever cases and examined under microscope. Mosquitoes were assayed for the presence of sporozoites by enzyme-linked immunosorbent assay (ELISA) technique and sibling species by polymerase chain reaction (PCR). There are two highly efficient vectors i.e. Anopheles culicifacies and An. fluviatilis. In monsoon season of 2009, the man hour density for An. culicifacies was 36.2 which declined to 10.9 during monsoon season of 2010-14 (t = 6.52; p < 0.0001). Epidemiological results revealed that malaria positivity was declined from 27% in 2009–3% in 2014 (Trend chi2 = 57.21; p < 0.0001) and P. falciparum declined from 23.6 to 2.4% (Trend chi2 = 48.33; p < 0.0001). Spleen rate was declined from 47% in 2009–5% in 2014 (χ2 for trend = 6.1; p = 0.0135). Baigachak has achieved a remarkable 89% reduction in malaria. This study confirms that the control strategies undertaken in this study are useful and should be extended at multiple sites for further validation.

IMPLICATIONS OF LONG-LASTING INSECTICIDE-TREATED BED NETS (LLINs) FOR MALARIA CONTROL AND PREVENTION IN SOMALIA

In Sub-Saharan Africa, bed nets are mainly aimed at the prevention of the nuisance of mosquito biting rather than against malaria. The species that are involved in malaria infection are all present in Somalia with the leading one being Plasmodium falciparum that causes about 98% of all infections in the country. This alarming spread of malaria underscores the need to develop interventions that can effectively curb the malaria menace. This study sought to examine the implications of the utilization of long-lasting insecticide-treated bed nets (LLINs) for malaria control and prevention. The population constituted 1,100 pregnant women attending MCH clinics and the two thousand two hundred heads of households, totalling three thousand three hundred. A simple random sampling technique was used to obtain a representative sample of households. In surveying 110 pregnant women attending Maternal Child Health (MCH) clinics and 220 heads of households in the Belet Hawo district in Somalia in 2019, the study found that the majority of households knew the effect of LLINs on preventing malaria. They were also knowledgeable about how to control malaria while facing limited access to LLINs. Furthermore, LLIN usage helped households to raise awareness and knowledge about the effect of LLINs on preventing malaria. This study provided the Somalian government with a better understanding of the causes, control, and prevention of malaria.

Factors Associated with Malaria Preventive Measures among Pregnant Women in Guinea.

Background Malaria control interventions have been scaled up, particularly those in pregnant women in Guinea. Despite that, coverage of key malaria preventive measure (MPM) indicators remains low. Therefore, it is vital to understand the reasons behind that, especially for the low coverage of sulfadoxine-pyrimethamine (SP) and long-lasting insecticide-treated bed nets (LLIN). Methods We conducted a cross-sectional survey in nine district hospitals in Guinea. Pregnant women received for delivery were interviewed to collect sociodemographic and obstetrical parameters. Associated factors with MPMs were investigated through univariate analysis and classification and regression tree (CART). Results A total of 2248 parturients participated in this study. Among pregnant women using mosquito nets (63.5% (61.4%, 65.5%)), only 41.2% (39.1%, 43.3%) had used it regularly during the last two weeks preceding delivery. Similarly, most pregnant women (57.9% (55.8%, 59.9%)) had received less than three doses of SP, and only a few pregnant women (23.9% (22.1%, 25.7%)) have benefited from full MPMs. Parturient's age, marital status, time spent in residence, place of residence, level of education, distance from home to the health centre, health conditions, occupation, head of the household's occupation, the presence of garbage and stagnant water in the neighbourhood, source of running water, and the number of pregnancies were significantly statistically associated with MPMs in pregnant women. However, the number of antenatal care visits (ANC), means of transportation used by the pregnant woman to accomplish ANCs, and stagnant water in the neighbourhood were the three preponderant factors. Conclusion The low coverage of SP and LLINs among pregnant women requires revitalising some strategies, especially improving ANC coverage and more efforts to reduce inequalities in access to those services due to sociodemographic status. Education on the benefits of these MPMs should also be emphasised.

Effectiveness of a national mass distribution campaign of long-lasting insecticide-treated nets and indoor residual spraying on clinical malaria in Malawi, 2018–2020

IntroductionMalawi’s malaria burden is primarily assessed via cross-sectional national household surveys. However, malaria is spatially and temporally heterogenous and no analyses have been performed at a subdistrict level throughout the...

Relationship between the Usage of Long-Lasting Insecticide-Treated Bed Nets (LLITNs) and Malaria Prevalence among School-Age Children in Southwestern Nigeria.

Purpose The usage of LLITNs in malaria vector control has resulted in the reduction in malaria deaths among higher-risk groups (pregnant women and under-fives). However, there exists asymptomatic infection among older children, thereby making them a reservoir of malaria transmission. This study aimed at assessing the impact of LLITN usage on malaria prevalence among school-age children (SAC) in Ekiti, South Western Nigeria. Methods Cross-sectional, two-stage cluster sampling technique was used to collect data from SAC during May and June 2017. A total of 1313 (Oye LGA: 657 and Ikole LGA: 656) SAC in selected public primary schools participated in the study. Sociodemographic information as well as data on LLITN usage the previous night was obtained using pretested, semistructured questionnaires adapted from the standardized Malaria Indicator Survey (MIS) tools. Malaria infection was diagnosed by using the rapid diagnostic test (RDT) on blood samples that were collected by finger prick from each child. Data were analyzed using the Statistical Package for Social Sciences (SPSS) for Windows software version 26 (SPSS Inc., Chicago, IL, USA). Results Usage of LLITNs among SAC was significantly higher in Ikole LGA than in Oye (p < 0.001). Socioeconomic factors (access to electricity, mother's occupation, and household size) showed significant associations with LLITN usage (p < 0.001) in both Oye and Ikole LGAs. Malaria prevalence was significantly low among SAC utilizing LLITNs in both Oye and Ikole LGAs (p < 0.001). There was a significant association between gender and malaria prevalence among SAC with males having higher prevalence than females (p < 0.001). Socioeconomic factors were significantly associated with malaria prevalence in both LGAs (p < 0.001). Conclusion The usage of LLITNs caused a significant reduction in malaria prevalence among the school-age children in the study areas; hence, sensitization on usage should be scaled up towards malaria elimination.

Out-of-pocket costs and time spent attending antenatal care services: a case study of pregnant women in selected rural communities in Zinder, Niger

BackgroundDespite an official policy of exemption from health care costs, pregnant women in Niger still face some out-of-pocket costs (OPC) in addition to time costs when they attend antenatal care (ANC) services. We aimed to: 1) assess the OPC for pregnant woman attending ANC, 2) estimate the time spent to attend ANC and the opportunity cost of that time, and 3) assess how OPC and time spent to attend ANC affected ANC attendance.MethodsData were obtained from a quasi-experimental descriptive study carried out in the region of Zinder, Niger, which compared pre- and post-intervention cohorts of pregnant women (n = 1736 women who reported attending ANC during their current pregnancy). An ANC attendance score was developed to describe the timing of ANC attendance in regard to the WHO recommendation of attending 4 ANC sessions. OPC and time spent were evaluated separately for associations with ANC attendance using Spearman correlations.ResultsThe mean (±SD) age of pregnant women was 25.0 ± 6.4 yr, 19.0% were ≤ 19 yr and 99.7% were in their second or third trimester of gestation at the time of the interview. Among those who were > 13 weeks and > 27 weeks of gestation, 4.0 and 74.4% had attended ANC during their first and second trimesters, respectively. The median (1st quartile (Q1), 3rd quartile (Q3)) ANC score was 0 (− 1, 0), reflecting that the majority of women failed to follow the WHO recommendation. More than half of the women (72.5%) experienced OPC related to ANC. The majority of women (> 80%) reported spending ~ 3 h for an ANC visit, including travel and waiting time. Time spent to attend ANC was not associated with ANC attendance score. Women who experienced OPC, and those who received iron folic acid (IFA) or long-lasting insecticide-treated bednets during an ANC visit, were more likely to have a higher ANC attendance score compared to those who did not.ConclusionOPC and time spent were not identified as barriers to ANC visits, and IFA and long-lasting insecticide-treated bednets distribution could be used to motivate pregnant women to attend ANC.Trial registrationThe NiMaNu project was registered at www.clinicaltrials.gov as NCT01832688. Registered 16 April 2013.

Optimal control of a malaria model with long-lasting insecticide-treated nets

&lt;abstract&gt;&lt;p&gt;A deterministic multi-stage malaria model with a non-therapeutic control measure and the effect of loss of immunity due to the use of the Long-Lasting bednets with a control perspective is formulated and analyzed both theoretically and numerically. The model basic reproduction number is derived, and analytical results show that the model's equilibria are locally and globally asymptotically stable when certain threshold conditions are satisfied. Pontryagin's Maximum Principle with respect to a time dependent constant is used to derive the necessary conditions for the optimal usage of the Long-Lasting Insecticide-treated bednets (LLINs) to mitigate the malaria transmission dynamics. This is accomplished by introducing biologically admissible controls and $ \epsilon\% $-approximate sub-optimal controls. Forward-backward fourth-order Runge-Kutta method is used to numerically solve the optimal control problem. We observe that the disadvantage (loss of immunity, even at its maximum) in the use of bednets is compensated by the benefit of the number of susceptible/infected individuals excluded from the malaria disease dynamics, the only danger being the poor use of the long-lasting bednets. Moreover, it is possible to get closer to the optimal results with a realistic strategy. The results from this study could help public health planners and policy decision-makers to design reachable and more practical malaria prevention programs "close" to the optimal strategy.&lt;/p&gt;&lt;/abstract&gt;

Seroprevalence and associated risk factors of Dengue fever in Kassala state, eastern Sudan.

Dengue is a rapidly growing public health threat in Kassala state, eastern Sudan. The objective of this study was to determine the seroprevalence, entomological transmission indices, and socioeconomic risk factors associated with dengue in this region. A cross-sectional community-based study was conducted in four dengue-endemic sites; Khatmia, West Gash, Thoriba, and Shokriya between March 2016 to March 2017. Enzyme-linked immunosorbent assay (ELISA) of immunoglobulin G (IgG) was used to determine the prevalence of dengue virus among the study participants. An entomological survey was conducted using pyrethrum spray catch and dipping for the collection of adults and aquatic stages of Aedes aegypti, respectively. Ribonucleic acid was extracted from the buffy coat of participants as well as from adult female Ae. aegypti to assess the possible circulation of dengue virus using Reverse Transcription Polymerase Chain Reaction (RT-PCR). Multiple logistic regression model was used to estimate the association between potential risk factors and dengue seropositivity. A total of 409 persons were recruited to the study: 45.5% were in the 20–39 years’ age category; 57.9% were living in houses with 6–10 persons; and 29.1% had at most secondary school education. In the majority (65.8%) of the households, the socioeconomic status was low (P<0.001). Long-lasting insecticide-treated bed nets were used in 56.5% of the households. Over three-quarters (77.8%) claimed not to have experienced febrile illness in the last three months. Routine entomological survey across Kassala state identified a total of 3,304 larvae and 390 pupae Ae. aegypti, respectively. The overall house index was 32.8% and Breteau Index was 35.96% (146/406). The overall pupal demographic index was 13.31%, and the pupal children index was 97.26%. Antibodies against IgG were detected from 66 (42.04%) out of a total of 157 sera. Twenty-two positive sera (75.9%) were collected from Khatmia. A total of 329 adults Ae. aegypti were identified but only one (0.3%) was positive for DENV in Khatmia. Finally, four independent risk factors were identified to derive dengue circulation in Kassala: elder age (> 60 years) (OR 6.31, CI 1.09–36.36); type of bathroom (OR 3.52, CI 1.35–9.20); using water-based air conditioner (OR 6.90, CI 1.78–26.85) and previous infection of any household member with dengue (OR 28.73, CI 3.31–249.63). Our findings suggest that Kassala state is facing an increasing occurrence of dengue and emphasizes the need for developing appropriate interventions to address the identified risk factors, and place control programs into actions. Establishment of routine dengue epidemiological and entomological surveillance, and climate warning systems will contribute to early warning and timely detection and response to emerging outbreaks.