Indoor Residual Spraying Research Articles

Monitoring alpha-cypermethrin susceptibility of Phlebotomus argentipes, the vector of visceral leishmaniasis in India, using the CDC bottle bioassay

BackgroundVisceral leishmaniasis (VL), known as Kala-azar on the Indian subcontinent, is a parasitic disease caused by the flagellated protozoa Leishmania donovani and can be fatal if left untreated. The sand fly Phlebotomus argentipes is the only proven vector of VL in the Southeast Asia region, and VL control in this region has relied on the use of synthetic insecticides for indoor residual spraying (IRS). The use of DDT in VL control programmes has led to the development of resistance to this insecticide in sand flies, resulting in DDT being replaced with the insecticide alpha-cypermethrin. However, alpha-cypermethrin has a similar mode of action as DDT and, therefore, the risk of resistance development in sand flies increases under the pressure of regular exposure to this insecticide. In the present study we assessed the susceptibility status of wild-caught sand flies and F1 progeny using the CDC bottle bioassay.MethodsSand flies were collected from 10 villages in Muzaffarpur District, Bihar, India. Eight of these villages are receiving continuous IRS with alpha-cypermethrin, one village had discontinued IRS with alpha-cypermethrin and one village had never received IRS with alpha-cypermethrin. The collected sand flies were exposed to a pre-determined diagnostic dose for a specific time duration (3 µg/ml for 40 min), and knockdown and mortality at 24 h post-exposure were recorded.ResultsKnockdown ranged from 91.19% to 99.47% for wild-caught sand flies and from 91.70% to 98.89% for their F1 progeny. At 24 h post-exposure, mortality ranged from 89.34% to 98.93% for wild-caught sand flies and from 90.16% to 98.33% for F1 progeny.ConclusionsThe results of this study showed that P. argentipes is potentially developing resistance, signalling the need for continuous monitoring and vigilance to sustain the validation of elimination once achieved.Graphical

Malaria parasite burden and heterogeneity of risk factors among Central African Republic refugees: a cross-sectional study in the Gado-Badzere refugee camp in Eastern Cameroon

BackgroundRefugees are vulnerable populations especially in malaria endemic areas where the disease claims many lives and constitutes an emerging challenge for humanitarian response. This study assessed how the influx and settlement of Central African Republic (CAR) refugees influences malaria burden in the Gado-Badzere refugee camp, Eastern Cameroon.MethodsA cross-sectional malariometric survey was conducted between November 2022 and October 2023 in 324 households comprising 1,304 individuals aged 1 month and above. Malaria parasite burden was determined using rapid diagnostic tests (RDTs) and Giemsa-stained microscopy. Demographic characteristics, malaria risk factors, treatment-seeking behaviors and costs to cure malaria were assessed using semi-structured questionnaires.ResultsOf the 1,304 participants, 525 (40.3%) were malaria parasite positive with moderate geometric mean parasite density (GMPD) of 1100 parasites/μl of blood. Plasmodium falciparum was the main species (99.8%), with mixed P. vivax infections (0.2%). Insecticide treated net (ITN) ownership was 53.7%, but its utilization was significantly low (22.4%) (P < 0.001). Reason for no ITN ownership was net damaged (74.7%). Net insufficiency (77.8%) accounted for non-frequent ITN use. Mean expenditure to treat malaria in the hospital was higher (USD 13.64 ± 8.67) than auto-medication (USD 1.13 ± 1.18). Significantly, malaria parasite prevalence and risk were higher for 0-5 years age (43.7%, OR = 1; P = 0.02), residents of sector 8 (49.2%, OR = 2.53; P < 0.001) of the camp, non-frequent ITN users (41.7%, OR = 2.08; P < 0.001), people living around stagnant water (44.4%, OR = 1.55; P < 0.001) and during the rainy season (43.5%, OR = 1.31; P = 0.02). The GMPD/µl was significantly higher in the 0-5 years age group (1456, P < 0.0001), inhabitants of sector 9 (1626, P = 0.04) and participants living around stagnant water (2097, P = 0.01).ConclusionThe malaria burden in CAR refugees may represent the reservoir for malaria transmission, especially with the circulation of P. vivax. The improper use of ITNs could be ameliorated through sensitization. Seasonal chemoprevention mainly during the rainy season and Indoor Residual Spraying (IRS) might be implemented for effective malaria control in refugee settings.

Prevalence and factors associated with placental malaria in Lira District, Northern Uganda: a cross-sectional study

BackgroundMalaria has a stable perennial transmission across Uganda. Placental malaria is associated with adverse maternal, fetal, and neonatal outcomes. The factors associated with placental malaria are poorly understood in the study setting. The aim of the study was to assess the prevalence of placental malaria and to determine its associated factors among parturient women in Lira District, Uganda.MethodsThis was a cross-sectional study among 366 pregnant women who delivered at Lira Regional Referral Hospital. Data were collected from December 2018 to February 2019 using an interviewer-administered questionnaire. The variables were socio-demographic, obstetric characteristics, and malaria preventive practices. Standard Diagnostic Bioline Rapid Diagnostic Tests were used to detect placental malaria present in placental blood. Microscopy was used to quantify the grade of placental malaria parasitaemia. Logistic regression was used to assess factors associated with placental malaria.ResultsThe mean age of the participants was 25.34 years (standard deviation [SD] 5.73). The prevalence of placental malaria was [4.4% (16/366) 95% CI (2.5 to 7.0)]. Of these, only 7/16 were positive on microscopy, with 2/7 having moderate parasitemia and 5/7 having mild parasitaemia. Women aged less than 20 years [AOR 3.48, 95% CI (1.13 to 10.72)], and those not taking iron supplements during pregnancy [AOR = 3.55, 95% CI (1.02 to 12.31)] were associated with an increased likelihood of having placental malaria.ConclusionThe prevalence of placental malaria was low in this setting. This may have reflected the low malaria transmission rates following intensive indoor residual spraying. Placental malaria infection was associated with younger age and not taking iron supplements during pregnancy. Public health measures need to scale up and emphasise adherence to malaria preventive measures during pregnancy especially among teenage mothers.

Socio-demographic factors, housing characteristics, and clinical symptoms associated with falciparum malaria in two rapidly urbanizing areas in the Ashanti region of Ghana

BackgroundMalaria has been described as a disease of poverty, affecting the poorest populations typically living in rural areas. As hitherto rural areas transition into semi-urban environments, this study investigated the prevalence of falciparum malaria and associated risk factors in two rapidly urbanizing districts in the Ashanti Region of Ghana.MethodsA cross-sectional, hospital-based study was conducted at Agona and Mankranso Government Hospitals located within the Sekyere South and Ahafo Ano Southwest districts respectively, in the Ashanti Region of Ghana. Five µL of venous blood was obtained from suspected malaria patients and tested for malaria using rapid diagnostic test (RDT). Data on socio-demographic factors, clinical symptoms, and housing characteristics were collected using a structured questionnaire. Univariate and multivariate logistic regression analysis were performed to identify risk factors associated with malaria.ResultsA total of 1739 participants were enrolled in the study between January and June 2021 with median age of 22 years (IQR = 6–36). Overall malaria prevalence was 24.8%. Compared to > 30-year-olds, children between 0 and 5 years (aOR = 3.36) and those aged between 6 and 14 (aOR = 6.71) were three and six times more likely to test positive for malaria, respectively. Similarly, farming (aOR = 1.74), compared to other occupations, living close to stagnant water (aOR = 1.34), experiencing chills (aOR = 1.5), and vomiting (aOR = 1.93) were associated with increased odds of malaria infection. Having roofing ceiling (aOR = 0.66) and screened doors (aOR = 0.75) were associated with decreased risk of malaria. However, sleeping under insecticide-treated nets (ITNs), using mosquito coils/repellents, and indoor residual spraying (IRS) were not statistically significantly associated with infection.ConclusionChildren between 0 and 5 years and those aged between 6 and 14 years continue to shoulder the highest burden of malaria. Efforts to improve housing characteristics such as installation of roofing ceiling, screening doors, and clearing potential mosquito breeding sites should be encouraged in these rapidly urbanizing areas.

The Prevalence of Childhood Asthma, Respiratory Symptoms and Associated Air Pollution Sources Among Adolescent Learners in Selected Schools in Vhembe District, South Africa.

A cross-sectional survey was conducted with 2855 adolescents from fourteen (14) selected schools in communities exposed to high levels of air pollution from indoor residual spraying (IRS) that is used for malaria vector control in the Vhembe region. Data were collected using a self-administered standardized International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Statistical software STATA version 17 was used to analyze the data. Binary logistic regression was used to determine the relationship between air pollution sources and childhood asthma/symptoms. The prevalences of asthma, 'wheeze ever' and 'wheeze in the past' were 18.91%, 37.69% and 24.69%, respectively. The results from the adjusted binary logistic regression model indicated that exposure to tobacco smoke (OR = 1.84; 95% CI: 1.08-3.16), smoking a water pipe (OR = 1.65; 95% CI: 1.16-2.36) and the use of paraffin as fuel for heating (OR = 1.70; 95% CI: 0.97-2.88) and cooking (OR = 0.48; 95% CI: 0.29-1.00) were significant risk factors for asthma. Trucks passing through the streets, having a cat at home and using open fires were significantly associated with 'wheeze in the past'. Finally, using gas for cooking (OR = 0.72; 95% CI: 0.53-0.99), open fires for heating (OR = 0.53; 95% CI: 0.35-0.80) and smoking a water pipe (OR = 2.47; 95% CI: 1.78-3.44) were associated with 'wheeze ever'. School children living in these communities had an increased risk of developing asthma and presenting with wheezing due to exposure to environmental air pollution sources.

Efficacy of attractive targeted sugar bait stations against malaria in Western Province Zambia: epidemiological findings from a two-arm cluster randomized phase III trial

BackgroundAttractive targeted sugar bait (ATSB) stations containing bait (to attract) and ingestion toxicant (to kill) sugar-foraging mosquitoes are hypothesized to reduce malaria transmission by shortening the lifespan of Anopheles vectors.MethodsA two-arm cluster-randomized controlled trial (cRCT) was conducted in Western Province Zambia. Seventy clusters of 250–350 households were assigned (1:1) by restricted randomization to an intervention arm (ATSB) or control arm (no ATSB) in the context of standard of care vector control (insecticide-treated nets and/or indoor residual spraying). Two ATSB stations (Westham Sarabi, 0.11% dinotefuran w/w) were maintained on exterior walls of eligible household structures for a 7-month deployment period (December-June) during the high malaria transmission season. The primary outcome was clinical malaria incidence among two consecutive seasonal cohorts of children aged 1–14 years, followed-up monthly from January-June in 2022 and 2023. Secondary outcome was Plasmodium falciparum prevalence among individuals aged over six months. Analysis compared clinical malaria incidence and prevalence between arms among the intention-to-treat population.ResultsATSB coverage, assessed by cross-sectional survey, was 98.3% in March–April 2022 and 89.5% in March–April 2023. 4494 children contributed any follow-up time to the cohort, with 2313 incident malaria cases in the intervention arm (1.28 per child per six-month transmission season), and 2449 in the control arm (1.38 per child-season). The incidence rate ratio between the two arms was 0.91 (95% CI 0.72–1.15, p = 0.42). 2536 individuals participated in cross-sectional surveys, with prevalence of P. falciparum 50.7% in the intervention arm and 53.5% in the control arm. The odds ratio between the two arms was 0.89 (95% CI 0.66–1.18, p = 0.42). Secondary covariable-adjusted and subgroup analyses did not substantially alter the findings. No serious adverse events associated with the intervention were reported.ConclusionsTwo ATSB stations deployed per eligible structure for two consecutive transmission seasons did not result in a statistically significant reduction in clinical malaria incidence among children aged 1–14 years or in P. falciparum prevalence in rural western Zambia. Further studies are needed to assess the efficacy of ATSB stations in different settings and with different deployment strategies.Trial registrationThe trial is registered with Clinicaltrials.gov (NCT04800055).

Environmental Factors to Malaria Incidence : A Literature Review

Malaria remains a major public health concern in Indonesia, particularly due to its high mortality rate among children under five, accounting for approximately two-thirds of all cases. The disease is transmitted by female Anopheles mosquitoes, which carry the Plasmodium parasite. In 2019, malaria caused 409,000 deaths globally, with 229 million cases reported, particularly in remote areas with poor access to healthcare, commonly in low-income countries. This literature review highlighted the environmental risk factors contributing to malaria incidence, based on studies from 24 scientific journals using data from the Sinta and Scopus databases. The study identified key environmental factors, including physical, chemical, biological, and socio-cultural elements, with the most significant risk linked to vector breeding sites. Among the reviewed articles, 62.5% (15 out of 24) found a statistically significant association between the presence of mosquito breeding sites and malaria incidence. Additional risk factors included the use of mosquito nets, housing conditions (specifically wall density), and nighttime outdoor activities. Effective malaria control measures require addressing these environmental factors, as they play a crucial role in the disease’s transmission. Strategies to disrupt the transmission cycle include eliminating mosquito breeding sites, applying larvicides to stagnant water, cleaning vector resting areas, promoting the use of insecticide-treated nets, and implementing Indoor Residual Spraying (IRS). A community-based, integrated approach to environmental management is essential to reducing malaria transmission and controlling its spread in affected regions.

Assessing agricultural practices and insecticides resistance for effective malaria vector control in northwestern Iran

BackgroundAfter three years with no local transmission of malaria, an outbreak occurred in Iran in 2022. Key malaria control methods in Iran are including indoor residual spraying (IRS), long-lasting insecticide-treated nets (LLINs), and prompt diagnosis and treatment of malaria cases. Anopheles sacharovi is one of the main malaria vectors in Iran. This study aimed to determine the insecticides resistance status of An. sacharovi in northwestern Iran, to inform effective vector control programs in this region.MethodsLarval stages of An. sacharovi were collected from various larval habitats located in the villages along the Aras River. Adult susceptibility tests were performed on An. sacharovi using diagnostic doses of insecticides accordance to World Health Organization (WHO) guidelines. The study also evaluated agricultural insecticide and fertilizer usage alongside the presence of natural mosquito predators in breeding sites in the study area.ResultsAlongside various chemicals such as silica, humic acid, superphosphate, sulfur, urea, and solupotasse at different dose levels, organophosphorus and pyrethroid insecticides are commonly used in rice fields and orchards. Anopheles sacharovi displayed diverse reactions to insecticides, demonstrating resistance to DDT but sensitivity to malathion, and showing similar reactions to carbamate and pyrethroid insecticides.ConclusionsThese results provide significant insights into agricultural practices and the presence of mosquito larvae in the study area. The extensive use of a specific herbicide illustrates its popularity among farmers for weed control, while other agricultural products focus on enhancing soil fertility and productivity. The absence of mosquito larvae in habitats with predators indicates the usefulness of these predators in controlling the population of mosquitoes. The resistance of mosquitoes to certain insecticides highlights the need for careful selection and intermittent use of insecticides in vector control programs. These findings can inform the development of targeted strategies to reduce malaria transmission risks. Further research is essential for assessing the effectiveness of these interventions.

Emerging public health strategies in malaria control: innovations and implications.

Malaria remains a significant global health challenge, particularly in regions with limited resources and tropical climates. Despite extensive efforts, the disease continues to cause significant morbidity and mortality, with ~229 million cases and 409000 deaths reported in 2020. However, recent years have seen promising advancements in public health strategies aimed at malaria control and elimination. Technological advancements have played a crucial role in improving malaria control efforts. Genomic surveillance techniques enable the monitoring of malaria parasite populations, aiding in the detection of drug resistance and informing targeted interventions. Additionally, innovative diagnostic technologies, such as rapid diagnostic tests (RDTs) and molecular assays, have enhanced the speed and accuracy of malaria diagnosis, facilitated prompt treatment and reduced transmission. These tools are instrumental in achieving the WHO goals of reducing malaria cases and deaths by at least 90% by 2030. Novel vector control methods offer innovative approaches to reduce malaria transmission. Insecticide-treated nets (ITNs) and indoor residual spraying (IRS) remain foundational strategies, with advancements including the development of next-generation insecticides and long-lasting insecticidal nets (LLINs). Furthermore, genetic modification of mosquitoes, such as gene drive technology, holds promise for reducing mosquito populations and interrupting malaria transmission. These vector control innovations complement other strategies, contributing to comprehensive malaria control efforts aimed at achieving sustainable disease reduction and eventual elimination.

Effect of Indoor Residual Spraying on Malaria in Pregnancy and Pregnancy Outcomes: A Systematic Review.

Malaria in pregnancy increases maternal and perinatal morbidity and mortality. Indoor residual spraying (IRS) is a core vector control strategy used to reduce transmission in endemic areas; however, its efficacy in reducing the sequelae of malaria in pregnancy is not well described. PubMed, Embase, Cochrane, and Web of Science were searched for all studies assessing IRS exposure during pregnancy. Abstracts and full texts were reviewed independently by two researchers, with discrepancies adjudicated by a third. Of 3,319 studies that met the search criteria, 17 met the inclusion criteria. Thirteen studies reported on the effect of IRS on malaria endpoints during pregnancy, five on birth outcomes, and one on a fetal anomaly. Twelve of the 13 studies exploring maternal malaria and 3 of 3 studies reporting on placental malaria demonstrated a reduction among those exposed to IRS during pregnancy. Results were more mixed for obstetric outcomes. Two of the best-quality studies showed reductions in preterm birth, low birthweight, and fetal/neonatal mortality; a third high-quality study did not demonstrate a reduction in perinatal mortality but did not evaluate preterm birth. One study found a significantly increased risk of preterm birth in those exposed to IRS, although the study was of lower quality. A final study demonstrated a small, although statistically significant, association between IRS and male urogenital birth defects. In malaria-endemic areas, the published literature suggests that IRS during pregnancy reduces the incidence of malaria parasitemia. However, without high-quality prospective studies directly examining IRS in pregnancy, the impact on birth outcomes is less clear.

Anopheles gambiae Re-Emergence and Resurgent Malaria Transmission in Eastern Rwanda, 2010-2020.

Rwanda achieved unprecedented malaria control gains from 2000 to 2010, but cases increased 20-fold between 2011 and 2017. Vector control challenges and environmental changes were noted as potential explanations, but no studies have investigated causes of the resurgence or identified which vector species drove transmission. We conducted a retrospective study in four sites in eastern Rwanda that conducted monthly entomological surveillance and outpatient malaria care. We compared sporozoite rates, human blood index (HBI), and relative abundance of the primary vectors, Anopheles gambiae and Anopheles arabiensis, from 2017 to 2020. We then modeled the effects of vector control interventions, insecticide resistance, and temperature changes on species composition and reported malaria incidence. Sporozoite rates were 28 times higher and HBI was four times higher in An. gambiae compared with An. arabiensis. Insecticide-treated bed nets, first distributed nationally in 2010, were associated with decreased An. gambiae relative abundance. However, increased pyrethroid resistance was associated with increased An. gambiae relative abundance and malaria incidence. Epidemic malaria peaks corresponded to periods of model-predicted An. gambiae re-emergence, and increased regional air temperatures during the period were further associated with increased malaria incidence. Indoor residual spraying (IRS), implemented with non-pyrethroid insecticides later in the period, was associated with 86% reductions in An. gambiae relative abundance and 75% reductions in malaria incidence. These findings suggest that increased pyrethroid resistance and the re-emergence of An. gambiae were closely linked to the malaria resurgence in eastern Rwanda. Non-pyrethroid IRS or other control measures that effectively target An. gambiae may help prevent future resurgences.

Insecticide Resistance and Target-Site Mutations kdr, N1575Y, and Ace-1 in Anopheles gambiae s.l. Populations in a Low-Malaria-Transmission Zone in the Sudanian Region of Senegal.

Background/Objectives: Significant progress in malaria control has been achieved through long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), raising hopes for malaria elimination. However, emerging insecticide resistance threatens these gains. This study assessed the susceptibility of Anopheles gambiae s.l. populations to public health insecticides, examined the frequencies of kdr, Ace-1, and N1575Y mutations, and explored their associations with phenotypic resistance in Dielmo and Ndiop, Senegal. Methods: Anopheles larvae collected between September and December 2022 were reared to adulthood. Adult mosquitoes were exposed to discriminating concentrations of various insecticides following WHO guidelines. Knockdown times (KDT50 and KDT95) for pyrethroids were calculated using the Probit model. RT-qPCR detected target-site mutations (kdr: L1014F and L1014S, Ace-1, N1575Y) and assessed correlations with phenotypic resistance. Species-specific PCR identified species within the An. gambiae complex. Results/Conclusions: The populations of Dielmo and Ndiop showed susceptibility to pirimiphos-methyl and bendiocarb, with no Ace-1 mutation detected. Resistance to DDT and pyrethroids was observed. The knockdown times indicated that alphacypermethrin and lambdacyhalothrin were more effective than permethrin and deltamethrin. The L1014F allele was widespread, while L1014S was absent in Ndiop and low in Dielmo. The N1575Y mutation occurred only in populations with L1014F. The L1014S mutation was significantly associated with resistance to lambdacyhalothrin in both villages and to deltamethrin in Ndiop.

Molecular xenomonitoring reveals Anopheles funestus and An. rivulorum as the primary vectors of lymphatic filariasis in coastal Kenya

BackgroundLymphatic filariasis (LF) is an infectious neglected tropical disease caused by mosquito-borne nematodes such as Wuchereria bancrofti, Brugia malayi, and Brugia timori. Globally, LF affects 51 million people, with approximately 863 million at risk in 47 countries. In Kenya, filariasis is endemic along the entire coastal strip, and more recently, at the Kenya–Ugandan border. The World Health Organization (WHO) recommends mass drug administration to reduce disease transmission and morbidity. Monitoring the effectiveness of such interventions relies on robust surveillance, achieved through microscopic examination of microfilariae in nighttime blood, detection of circulating filarial antigens (CFA), and molecular xenomonitoring. We focused on molecular xenomonitoring along the Kenyan coast due to its noninvasive nature and the opportunity to identify new vectors.MethodsIn 2022, mosquitoes were collected from Kilifi, Kwale, and Taita-Taveta counties located within the LF endemic region in Kenya. Subsequently, genomic deoxyribonucleic acid (gDNA) was extracted from these mosquitoes for speciation and analysis of Wuchereria bancrofti infection rates. The impact of sociodemographic and household attributes on infection rates was assessed using generalized estimating equations.ResultsA total of 18,121 mosquitoes belonging to Culicinae (63.0%, n = 11,414) and Anophelinae (37.0%, n = 6707) subfamilies were collected. Morphological identification revealed that Anopheline mosquitoes were dominated by An. funestus (45.4%, n = 3045) and An. gambiae (42.8%, n = 2873). Wuchereria bancrofti infection rates were highest in Kilifi (35.4%; 95% CI 28.0–43.3%, n = 57/161) and lowest in Taita Taveta (5.3%; 95% CI 3.3–8.0%, n = 22/412). The major vectors incriminated are An. rivulorum, An. funestus sensu stricto, and An. arabiensis. Mosquitoes of the An. funestus complex were significantly associated with LF transmission (OR 18.0; 95% CI 1.80–180; p = 0.014). Additionally, a higher risk of transmission was observed outdoors (OR 1.74; 95% CI 1.08–2.82; p = 0.024) and in homesteads that owned livestock (OR 2.00; 95% CI 1.09–3.66; p = 0.025).ConclusionsIn this study, we identified An. funestus s.l. sibling species, An. rivulorum and An. funestus s.s., as the primary vectors of lymphatic filariasis along the Kenyan coast. These findings also highlight that a significant portion of disease transmission potentially occurs outdoors where indoor-based vector control tools, including long-lasting insecticidal nets and indoor residual spray, may not be effective. Therefore, control measures targeting outdoor resting mosquitoes such as zooprophylaxis, larval source management, and attractive sugar baits may have potential for LF transmission reduction.Graphical

High-resolution spatio-temporal risk mapping for malaria in Namibia: a comprehensive analysis

BackgroundNamibia, a low malaria transmission country targeting elimination, has made substantial progress in reducing malaria burden through improved case management, widespread indoor residual spraying and distribution of insecticidal nets. The country's diverse landscape includes regions with varying population densities and geographical niches, with the north of the country prone to periodic outbreaks. As Namibia approaches elimination, malaria transmission has clustered into distinct foci, the identification of which is essential for deployment of targeted interventions to attain the southern Africa Elimination Eight Initiative targets by 2030. Geospatial modelling provides an effective mechanism to identify these foci, synthesizing aggregate routinely collected case counts with gridded environmental covariates to downscale case data into high-resolution risk maps.MethodsThis study introduces innovative infectious disease mapping techniques to generate high-resolution spatio-temporal risk maps for malaria in Namibia. A two-stage approach is employed to create maps using statistical Bayesian modelling to combine environmental covariates, population data, and clinical malaria case counts gathered from the routine surveillance system between 2018 and 2021.ResultsA fine-scale spatial endemicity surface was produced for annual average incidence, followed by a spatio-temporal modelling of seasonal fluctuations in weekly incidence and aggregated further to district level. A seasonal profile was inferred across most districts of the country, where cases rose from late December/early January to a peak around early April and then declined rapidly to a low level from July to December. There was a high degree of spatial heterogeneity in incidence, with much higher rates observed in the northern part and some local epidemic occurrence in specific districts sporadically.ConclusionsWhile the study acknowledges certain limitations, such as population mobility and incomplete clinical case reporting, it underscores the importance of continuously refining geostatistical techniques to provide timely and accurate support for malaria elimination efforts. The high-resolution spatial risk maps presented in this study have been instrumental in guiding the Namibian Ministry of Health and Social Services in prioritizing and targeting malaria prevention efforts. This two-stage spatio-temporal approach offers a valuable tool for identifying hotspots and monitoring malaria risk patterns, ultimately contributing to the achievement of national and sub-national elimination goals.

Assessment of Risk Factors Associated with Malaria Infection Among Adult Populations in Selected Internally Displaced Camps in Goma, North Kivu Province, Dr. Congo

Malaria remains a significant public health concern in many parts of the world, particularly in Africa. The Democratic Republic of the Congo (DRC) is one of the countries most heavily affected by malaria, with millions of cases reported annually. In the Eastern region of the DRC, ongoing conflict has resulted in large numbers of people living in precarious conditions within IDP camps, where the risk of malaria transmission is heightened due to unsuitable housing conditions, lack of bed net, overcrowded and unsanitary conditions with limited access to essential healthcare services. This study aims to assess the risk factors associated with malaria infection among adult populations in the Kashaka and Shabindu IDP camps in Goma, North Kivu Province. The study employed a cross-sectional design using a mixed-method approach. Data were collected from 371 households through interviews and medical record reviews. Chi-square tests were performed for bivariate analysis, and then logistic regression to evaluate the impact of multiple variables simultaneously. All participants pointed to mosquitoes as the causal agent. Around 97.8% confirmed that fever is the main symptom followed by chills (75.2%), headache (54.5%), and sweating (10.2%). Bed net was identified as a preventive measure at (100%), mosquito repellents (71.7%), and Indoor residual spraying (68;2%). Approximately 43.9% of households had at least one case of malaria with an increasing incidence in April (26.7%) and October (35.9%). The most significant factors affecting the spread of malaria were gender (OR: 1.73; p-value < 0.001), lack of bed net (OR: 5.231; p-value < 0.001), outdoor activities at night (OR: 0.661; p-value = 0.0364), and being close to sanitation facilities (OR: 2.458; p-value = 0.0013). These underscore the critical need for targeted malaria prevention measures, including increased bed net availability and usage, enhanced sanitation infrastructure, and heightened awareness about the dangers of outdoor nighttime activities.

A century of medical records reveal earlier onset of the malaria season in Haut-Katanga induced by climate change

BackgroundDespite worldwide efforts to eradicate malaria over the past century, the disease remains a significant challenge in the Democratic Republic of the Congo (DRC) today. Climate change is even anticipated...

Prevalence of Malaria among Patients Visiting Public Hospitals in Mogadishu, Somalia-Cross-Sectional Study

Background: In tropical and subtropical areas, malaria is one of the main causes of death and morbidity. Malaria is a major worldwide health concern, especially in sub-Saharan Africa, which includes Somalia, where the majority of cases and deaths from the disease occur. Malaria has a negative impact on both public health and the economic growth of many developing nations. Examining and quantifying the prevalence of malaria among outpatients who have visited hospitals were the study's goal. Study was conducted between September, and November 2023. Methods: A structured questionnaire was administered to 278 were collected patients visit two general hospitals at single time with obtained consented, blood samples were diagnosis used by rapid diagnosis test (RDTs), this study was identified the species of plasmodium used standard keys. Thus, this study design was cross-sectional and quantitative study. The data source was primary information, and was nonrandom sampling. The data generated was analysis using percentage and present in graph forms. Chi- square was used to determine the degree of association between malaria prevalence and factors influencing its transmission, performed by (SPSS 20 version). Results: total of 278 was recruited to conduct the study at outpatient department OPD in two hospitals, Mogadishu, Somalia. Out of 278 persons examined for malaria parasites, 12 (4.3%) were positive. Females were more participated than males 185 (66.5%). The respondents were observed 43.5% use it most of the time sleep under mosquito net. Conclusion: The investigation clearly showed that the persons with malaria infection was minimal. Because the participants aware of the threat posed by mosquitoes in their area, they placed a strong emphasis on vector control measures as reduce the number of mosquito breeding sites. They also understood the significance of indoor residual spray (IRS), which is essential for both mosquito prevention and control.

Impact of Indoor Residual Spray (IRS) and Insecticide Treated Nets (ITNs) for sand flies (Diptera: Psychodidae) elimination in some remote communities

Impact of Indoor Residual Spray (IRS) and Insecticide Treated Nets (ITNs) for sand flies (Diptera: Psychodidae) elimination in some remote communities

The TIRS trial: Enrollment procedures and baseline characterization of a pediatric cohort to quantify the epidemiologic impact of targeted indoor residual spraying on Aedes-borne viruses in Merida, Mexico.

Aedes mosquito-borne viruses (ABVs) place a substantial strain on public health resources in the Americas. Vector control of Aedes mosquitoes is an important public health strategy to decrease or prevent spread of ABVs. The ongoing Targeted Indoor Residual Spraying (TIRS) trial is an NIH-sponsored clinical trial to study the efficacy of a novel, proactive vector control technique to prevent dengue virus (DENV), Zika virus (ZIKV), and chikungunya virus (CHIKV) infections in the endemic city of Merida, Yucatan, Mexico. The primary outcome of the trial is laboratory-confirmed ABV infections in neighborhood clusters. Despite the difficulties caused by the COVID-19 pandemic, by early 2021 the TIRS trial completed enrollment of 4,792 children aged 2-15 years in 50 neighborhood clusters which were allocated to control or intervention arms via a covariate-constrained randomization algorithm. Here, we describe the makeup and ABV seroprevalence of participants and mosquito population characteristics in both arms before TIRS administration. Baseline surveys showed similar distribution of age, sex, and socio-economic factors between the arms. Serum samples from 1,399 children were tested by commercially available ELISAs for presence of anti-ABV antibodies. We found that 45.1% of children were seropositive for one or more flaviviruses and 24.0% were seropositive for CHIKV. Of the flavivirus-positive participants, most were positive for ZIKV-neutralizing antibodies by focus reduction neutralization testing which indicated a higher proportion of participants with previous ZIKV than DENV infections within the cohort. Both study arms had statistically similar seroprevalence for all viruses tested, similar socio-demographic compositions, similar levels of Ae. aegypti infestation, and similar observed mosquito susceptibility to insecticides. These findings describe a population with a high rate of previous exposure to ZIKV and lower titers of neutralizing antibodies against DENV serotypes, suggesting susceptibility to future outbreaks of flaviviruses is possible, but proactive vector control may mitigate these risks.

The impact of Bacillus thuringiensis var. israelensis (Vectobac® WDG) larvicide sprayed with drones on the bio-control of malaria vectors in rice fields of sub-urban Kigali, Rwanda

BackgroundThe core vector control tools used to reduce malaria prevalence are currently long-lasting insecticidal nets (LLINs), and indoor residual spraying (IRS). These interventions are hindered by insecticide resistance and behavioural adaptation by malaria vectors. Thus, for effective interruption of malaria transmission, there is a need to develop novel vector control interventions and technologies to address the above challenges. Larviciding using drones was experimented as an innovative tool that could complement existing indoor interventions to control malaria.MethodsA non-randomized larviciding trial was carried out in irrigated rice fields in sub-urban Kigali, Rwanda. Potential mosquito larval habitats in study sites were mapped and subsequently sprayed using multirotor drones. Application of Bacillus thuringiensis var. israelensis (Bti) (Vectobac® WDG) was followed by entomological surveys that were performed every two weeks over a ten-month period. Sampling of mosquito larvae was done with dippers while adult mosquitoes were collected using CDC miniature light traps (CDC-LT) and pyrethrum spraying collection (PSC) methods. Malaria cases were routinely monitored through community health workers in villages surrounding the study sites.ResultsThe abundance of all-species mosquito larvae, Anopheles larvae and all-species pupae declined by 68.1%, 74.6% and 99.6%, respectively. Larval density was reduced by 93.3% for total larvae, 95.3% for the Anopheles larvae and 61.9% for pupae. The total adult mosquitoes and Anopheles gambiae sensu lato collected using CDC-Light trap declined by 60.6% and 80% respectively. Malaria incidence also declined significantly between intervention and control sites (U = 20, z = − 2.268, p = 0.023).ConclusionsThe larviciding using drone technology implemented in Rwanda demonstrated a substantial reduction in abundance and density of mosquito larvae and, concomitant decline in adult mosquito populations and malaria incidences in villages contingent to the treatment sites. The scaling up of larval source management (LSM) has to be integrated in malaria programmes in targeted areas of malaria transmission in order to enhance the gains in malaria control.