Distribution Of Malaria Research Articles

Review of Anopheles Mosquito Species, Abundance, and Distribution in Ethiopia.

Background Malaria is a major mosquito-borne disease in Ethiopia, and it is one of the leading causes of morbidity and mortality. Plasmodium falciparum and P. vivax are the two malaria-causing parasitic species commonly known to cause human malaria in Ethiopia. To better manage and control vectors transmitting malaria parasites, the abundance, distribution, and updated annotated list of Anopheles species present in Ethiopia are very important. Methods In order to compile a list of the species recorded in Ethiopia, 33 original research articles were collected. This work gives an updated list of Anopheles mosquito species in Ethiopia and their abundance, distribution, and composition. Results According to this review, 110305 Anopheles mosquitoes were collected and 35 Anopheles species were recorded in different parts of Ethiopia. A. arabiensis was the most abundant when compared to other species, whereas A. maculipalpis and A. wilsonii were the least abundant species. The most abundant Anopheles species was recorded in central and the least abundant, from eastern Ethiopia. The second, third, and fourth abundant species were also collected from southern, northern, and western parts of Ethiopia.

Malaria infection and severe disease risks in Africa.

The relationship between community prevalence of Plasmodium falciparum and the burden of severe, life-threatening disease remains poorly defined. To examine the three most common severe malaria phenotypes from catchment populations across East Africa, we assembled a dataset of 6506 malaria admissions in children aged 3 months to 9 years from 2006 to 2020. Admissions were paired with data from community parasite infection surveys. A Bayesian procedure was used to calibrate uncertainties in exposure (parasite prevalence) and outcomes (severe malaria phenotypes). Each 25% increase in prevalence conferred a doubling of severe malaria admission rates. Severe malaria remains a burden predominantly among young children (3 to 59 months) across a wide range of community prevalence typical of East Africa. This study offers a quantitative framework for linking malaria parasite prevalence and severe disease outcomes in children.

Childhood malaria

Malaria Understanding how changes in community parasite prevalence alter the rate and age distribution of severe malaria is essential for optimizing control efforts. Paton et al. assessed the incidence of pediatric severe malaria admissions from 13 hospitals in East Africa from 2006 to 2020 (see the Perspective by Taylor and Slutsker). Each 25% increase in community parasite prevalence shifted hospital admissions toward younger children. Low rates of lifetime infections appeared to confer some immunity to severe malaria in very young children. Children under the age of 5 years thus need to remain a focus of disease prevention for malaria control. Science , abj0089, this issue p. [926][1]; see also abk3443, p. [855][2] [1]: /lookup/doi/10.1126/science.abj0089 [2]: /lookup/doi/10.1126/science.abk3443

PREVALENCE AND DISTRIBUTION OF MALARIA BY SEX, AGE GROUPS AND SPECIES IN YEAR 2019 IN SUSPECTED MALARIAL POPULATION OF DISTRICT D.I.KHAN, PAKISTAN

Background: Malaria is communicable disease that exists worldwide and is a cause of morbidity and mortality. Our objectives were to determine the prevalence and distribution of malaria by sex, age groups and species in year 2019 in suspected malarial population of District D.I.Khan, Pakistan.Materials Methods: This cross-sectional study was conducted in Department of Community Medicine, Gomal Medical College, D.I.Khan, Pakistan from October 1, 2020 to October 31, 2020. The data for malaria was retrieved from office of Frontier Primary Healthcare, D.I.Khan for 2019. A sample of 108,849 was calculated from population at risk of 1,306,655, with 0.258154 margin of error, 99% CI and 13.843% assumed prevalence of malaria. Sex, age groups, species and presence of malaria were our four nominal variables. Prevalence and distribution were described by count and percentage with 95% confidence intervals. Four hypotheses for prevalence and distribution were verified by chi-square goodness of fit test.Results: Out of a sample of 108,849 suspected malarial cases, 9,568 (8.79%, 95%CI, 8.62-8.95%) were positive. Out of 9,568 positive cases, 5,406 (4.97%) were men and 4,162 (3.82%) women, 1,062 (0.98%) in age group up to 5 years and 8,506 (7.81%) in age group 5 years and 9,121 (8.38%) were Plasmodium vivax, 437 (0.40%) were Plasmodium falciparum and 10 (0.009%) were mixed malarial infections. Our prevalence of malaria 8.79% was lower to 13.843% expected (p=.00001). Our distribution across sex (p=.00001), age groups (p=.03231) and species (p=.00001) were not similar to expected.Conclusion: The prevalence of malaria in year 2019 in suspected malarial population of District D.I.Khan, Pakistan was 8.79%. The prevalence was lower than expected for our population. The prevalence was higher for men, older age group (5 years) and for Plasmodium vivax. The prevalence for men was higher than expected for men and vice versa for women. The prevalence for age group up to 5 years was higher than expected for age group up to 5 years and vice versa for age group 5 years. The prevalence for Plasmodium vivax was higher than expected for Plasmodium vivax and vice versa for Plasmodium falciparum and mixed cases.

Residual malaria in Jazan region, southwestern Saudi Arabia: the situation, challenges and climatic drivers of autochthonous malaria

BackgroundSaudi Arabia and Yemen are the only two countries in the Arabian Peninsula that are yet to achieve malaria elimination. Over the past two decades, the malaria control programme in Saudi Arabia has successfully reduced the annual number of malaria cases, with the lowest incidence rate across the country reported in 2014. This study aims to investigate the distribution of residual malaria in Jazan region and to identify potential climatic drivers of autochthonous malaria cases in the region.MethodsA cross-sectional study was carried out from 1 April 2018 to 31 January 2019 in Jazan region, southwestern Saudi Arabia, which targeted febrile individuals attending hospitals and primary healthcare centres. Participants’ demographic data were collected, including age, gender, nationality, and residence. Moreover, association of climatic variables with the monthly autochthonous malaria cases reported during the period of 2010–2017 was retrospectively analysed.ResultsA total of 1124 febrile subjects were found to be positive for malaria during the study period. Among them, 94.3 and 5.7% were infected with Plasmodium falciparum and Plasmodium vivax, respectively. In general, subjects aged 18–30 years and those aged over 50 years had the highest (42.7%) and lowest (5.9%) percentages of malaria cases. Similarly, the percentage of malaria-positive cases was higher among males than females (86.2 vs 13.8%), among non-Saudi compared to Saudi subjects (70.6 vs 29.4%), and among patients residing in rural rather than in urban areas (89.8 vs 10.2%). A total of 407 autochthonous malaria cases were reported in Jazan region between 2010 and 2017. Results of zero-inflated negative binomial regression analysis showed that monthly average temperature and relative humidity were the significant climatic determinants of autochthonous malaria in the region.ConclusionMalaria remains a public health problem in most governorates of Jazan region. The identification and monitoring of malaria transmission hotspots and predictors would enable control efforts to be intensified and focused on specific areas and therefore expedite the elimination of residual malaria from the whole region.

Impact of an accelerated melting of Greenland on malaria distribution over Africa

Studies about the impact of future climate change on diseases have mostly focused on standard Representative Concentration Pathway climate change scenarios. These scenarios do not account for the non-linear dynamics of the climate system. A rapid ice-sheet melting could occur, impacting climate and consequently societies. Here, we investigate the additional impact of a rapid ice-sheet melting of Greenland on climate and malaria transmission in Africa using several malaria models driven by Institute Pierre Simon Laplace climate simulations. Results reveal that our melting scenario could moderate the simulated increase in malaria risk over East Africa, due to cooling and drying effects, cause a largest decrease in malaria transmission risk over West Africa and drive malaria emergence in southern Africa associated with a significant southward shift of the African rain-belt. We argue that the effect of such ice-sheet melting should be investigated further in future public health and agriculture climate change risk assessments.

Modeling the relationship between malaria prevalence and insecticide-treated bed net coverage in Nigeria using a Bayesian spatial generalized linear mixed model with a Leroux prior

OBJECTIVESTo evaluate malaria transmission in relation to insecticide-treated net (ITN) coverage in Nigeria.METHODSWe used an exploratory analysis approach to evaluate variation in malaria transmission in relation to ITN distribution in 1,325 Demographic and Health Survey clusters in Nigeria. A Bayesian spatial generalized linear mixed model with a Leroux conditional autoregressive prior for the random effects was used to model the spatial and contextual variation in malaria prevalence and ITN distribution after adjusting for environmental variables.RESULTSSpatial smoothed maps showed the nationwide distribution of malaria and ITN. The distribution of ITN varied significantly across the 6 geopolitical zones (p<0.05). The North-East had the least ITN distribution (0.196±0.071), while ITN distribution was highest in the South-South (0.309±0.075). ITN coverage was also higher in rural areas (0.281±0.074) than in urban areas (0.240±0.096, p<0.05). The Bayesian hierarchical regression results showed a non-significant negative relationship between malaria prevalence and ITN coverage, but a significant spatial structured random effect and unstructured random effect. The correlates of malaria transmission included rainfall, maximum temperature, and proximity to water.CONCLUSIONSReduction in malaria transmission was not significantly related to ITN coverage, although much could be achieved in attempts to curtail malaria transmission through enhanced ITN coverage. A multifaceted and integrated approach to malaria control is strongly advocated.

Avian malaria affecting penguins in zoological gardens, aquariums and wildlife parks in the UK

Avian malaria has caused mortalities in captive penguins worldwide and it is a conservation threat for some wild penguins. The experience of staff working on penguins is highly valuable for the improvement of captivity conditions. An online questionnaire was designed to collect avian malaria information in penguins in the UK. Volunteers with diverse experience reviewed it for scientific value and clarity, and it was supported by the British and Irish Association of Zoos and Aquariums. Forty-two institutions were contacted by email, obtaining 27 complete and five partial responses. Eighteen institutions reported avian malaria in 38 suspected and 37 confirmed outbreaks in the past 20 years, mainly occurring in the summer and recent years. Proportional risk was higher in the south east region of England. Humboldt and African penguins were more commonly affected, and prevalence was mostly low or medium, but lethality was high. Different treatment protocols were reported with inconsistent outcomes. Penguins' susceptibility, their translocation across institutions, and the wide distribution of avian malaria make this disease a constant threat. Preventive and control measures are recommended, including testing for early diagnosis and treatment, avoiding prolonged stressful events in penguins, and monitoring and controlling mosquito vectors.

Significant factors associated with malaria spread in Thailand: a cross-sectional study

PurposeThis paper aims to uncover new factors that influence the spread of malaria.Design/methodology/approachThe historical data related to malaria were collected from government agencies. Later, the data were cleaned and standardized before passing through the analysis process. To obtain the simplicity of these numerous factors, the first procedure involved in executing the factor analysis where factors' groups related to malaria distribution were determined. Therefore, machine learning was deployed, and the confusion matrices are computed. The results from machine learning techniques were further analyzed with logistic regression to study the relationship of variables affecting malaria distribution.FindingsThis research can detect 28 new noteworthy factors. With all the defined factors, the logistics model tree was constructed. The precision and recall of this tree are 78% and 82.1%, respectively. However, when considering the significance of all 28 factors under the logistic regression technique using forward stepwise, the indispensable factors have been found as the number of houses without electricity (houses), number of irrigation canals (canals), number of shallow wells (places) and number of migrated persons (persons). However, all 28 factors must be included to obtain high accuracy in the logistics model tree.Originality/valueThis paper may lead to highly-efficient government development plans, including proper financial management for malaria control sections. Consequently, the spread of malaria can be reduced naturally.

Climate change and the dynamics of age-related malaria incidence in Southern Africa

In the last decade, many malaria-endemic countries, like Zambia, have achieved significant reductions in malaria incidence among children <5 years old but face ongoing challenges in achieving similar progress against malaria in older age groups. In parts of Zambia, changing climatic and environmental factors are among those suspectedly behind high malaria incidence. Changes and variations in these factors potentially interfere with intervention program effectiveness and alter the distribution and incidence patterns of malaria differentially between young children and the rest of the population.We used parametric and non-parametric statistics to model the effects of climatic and socio-demographic variables on age-specific malaria incidence vis-à-vis control interventions. Linear regressions, mixed models, and Mann-Kendall tests were implemented to explore trends, changes in trends, and regress malaria incidence against environmental and intervention variables.Our study shows that while climate parameters affect the whole population, their impacts are felt most by people aged ≥5 years. Climate variables influenced malaria substantially more than mosquito nets and indoor residual spraying interventions. We establish that climate parameters negatively impact malaria control efforts by exacerbating the transmission conditions via more conducive temperature and rainfall environments, which are augmented by cultural and socioeconomic exposure mechanisms. We argue that an intensified communications and education intervention strategy for behavioural change specifically targeted at ≥5 aged population where incidence rates are increasing, is urgently required and call for further malaria stratification among the ≥5 age groups in the routine collection, analysis and reporting of malaria mortality and incidence data.

Abundance and Distribution of Malaria Vectors in Various Aquatic Habitats and Land Use Types in Kakamega County, Highlands of Western Kenya.

Management of malaria transmission relies heavily on vector control. Implementation and sustenance of effective control measures require regular monitoring of malaria vector occurrences, species abundance and distribution. The study assessed mosquito larval species composition, distribution and productivity in Kakamega County, western Kenya. A cross-sectional survey of Anopheline larvae was conducted in various aquatic habitats and land use types in Kakamega County, highlands of western Kenya between the month of March and June 2019. One thousand, five hundred and seventy six aquatic habitats were sampled in various land use types. The mean densities of An. gambiae s.l (46.2), An. funestus (5.3), An. coustani (1.7), An. implexus (0.13) and An. squamosus (2.0) were observed in fish ponds, burrow pits, drainage ditches, and tire tracks, respectively. High mean densities of An. gambiae s.l was reported in farmland (20.4) while high mean abundance of An. funestus s.l (8.2) and An. coustani s.l (4.0) were observed in artificial forests. The study revealed that the productivity of anopheles larvae varied across various habitat types and land use types. Therefore, treatment of potential breeding sites should be considered as an additional strategy for malaria vector control in Kakamega County, western Kenya.

The top 1%: quantifying the unequal distribution of malaria in Brazil

BackgroundAs malaria endemic countries strive towards elimination, intensified spatial heterogeneities of local transmission could undermine the effectiveness of traditional intervention policy.MethodsThe dynamic nature of large-scale and long-term malaria heterogeneity across Brazilian Amazon basin were explored by (1) exploratory analysis of Brazil’s rich clinical malaria reporting database from 2004 to 2018, and (2) adapting Gini coefficient to study the distribution of malaria cases in the region.ResultsAs transmission declined, heterogeneity increased with cases clustering into smaller subpopulations across the territory. In 2004, the 1% of health units with the greatest number of cases accounted for 46% of all reported Plasmodium vivax cases, whereas in 2018 52% of P. vivax cases occurred in the top 1% of health units. Plasmodium falciparum had lower levels of transmission than P. vivax, and also had greater levels of heterogeneity with 75% of cases occurring in the top 1% of health units. Age and gender stratification of cases revealed peri-domestic and occupational exposure settings that remained relatively stable.ConclusionThe pathway to decreasing incidence is characterized by higher proportions of cases in males, in adults, due to importation, and caused by P. vivax. Characterization of spatio-temporal heterogeneity and risk groups can aid stratification for improved malaria control towards elimination with increased heterogeneity potentially allowing for more efficient and cost-effective targeting. Although distinct epidemiological phenomena were clearly observed as malaria transmission declines, the authors argue that there is no canonical path to malaria elimination and a more targeted and dynamic surveillance will be needed if Brazil decides to adopt the elimination target.

Estimating the local spatio\u2010temporal distribution of malaria from routine health information systems in areas of low health care access and reporting

BackgroundReliable surveillance systems are essential for identifying disease outbreaks and allocating resources to ensure universal access to diagnostics and treatment for endemic diseases. Yet, most countries with high disease burdens rely entirely on facility-based passive surveillance systems, which miss the vast majority of cases in rural settings with low access to health care. This is especially true for malaria, for which the World Health Organization estimates that routine surveillance detects only 14% of global cases. The goal of this study was to develop a novel method to obtain accurate estimates of disease spatio-temporal incidence at very local scales from routine passive surveillance, less biased by populations' financial and geographic access to care.MethodsWe use a geographically explicit dataset with residences of the 73,022 malaria cases confirmed at health centers in the Ifanadiana District in Madagascar from 2014 to 2017. Malaria incidence was adjusted to account for underreporting due to stock-outs of rapid diagnostic tests and variable access to healthcare. A benchmark multiplier was combined with a health care utilization index obtained from statistical models of non-malaria patients. Variations to the multiplier and several strategies for pooling neighboring communities together were explored to allow for fine-tuning of the final estimates. Separate analyses were carried out for individuals of all ages and for children under five. Cross-validation criteria were developed based on overall incidence, trends in financial and geographical access to health care, and consistency with geographic distribution in a district-representative cohort. The most plausible sets of estimates were then identified based on these criteria.ResultsPassive surveillance was estimated to have missed about 4 in every 5 malaria cases among all individuals and 2 out of every 3 cases among children under five. Adjusted malaria estimates were less biased by differences in populations’ financial and geographic access to care. Average adjusted monthly malaria incidence was nearly four times higher during the high transmission season than during the low transmission season. By gathering patient-level data and removing systematic biases in the dataset, the spatial resolution of passive malaria surveillance was improved over ten-fold. Geographic distribution in the adjusted dataset revealed high transmission clusters in low elevation areas in the northeast and southeast of the district that were stable across seasons and transmission years.ConclusionsUnderstanding local disease dynamics from routine passive surveillance data can be a key step towards achieving universal access to diagnostics and treatment. Methods presented here could be scaled-up thanks to the increasing availability of e-health disease surveillance platforms for malaria and other diseases across the developing world.

Malaria in Southern Venezuela: The hottest hotspot in Latin America.

Malaria elimination in Latin America is becoming an elusive goal. Malaria cases reached a historical ~1 million in 2017 and 2018, with Venezuela contributing 53% and 51% of those cases, respectively. Historically, malaria incidence in southern Venezuela has accounted for most of the country's total number of cases. The efficient deployment of disease prevention measures and prediction of disease spread to new regions requires an in-depth understanding of spatial heterogeneity on malaria transmission dynamics. Herein, we characterized the spatial epidemiology of malaria in southern Venezuela from 2007 through 2017 and described the extent to which malaria distribution has changed country-wide over the recent years. We found that disease transmission was focal and more prevalent in the southeast region of southern Venezuela where two persistent hotspots of Plasmodium vivax (76%) and P. falciparum (18%) accounted for ~60% of the total number of cases. Such hotspots are linked to deforestation as a consequence of illegal gold mining activities. Incidence has increased nearly tenfold over the last decade, showing an explosive epidemic growth due to a significant lack of disease control programs. Our findings highlight the importance of spatially oriented interventions to contain the ongoing malaria epidemic in Venezuela. This work also provides baseline epidemiological data to assess cross-border malaria dynamics and advocates for innovative control efforts in the Latin American region.

Epidemic situation and diagnosis of imported malaria in Jiangsu, 2015-2019

Objective To elaborate the epidemic of imported malaria in Jiangsu province from 2015 to 2019, and to prevent the importation and re-transmission of malaria, and we provide information for malaria control and elimination. Methods Data on imported malaria cases in Jiangsu Province from 2015-2019 were collected and sorted through the National Infectious Diseases Information Reporting Management System (IDIRMS) and the Parasitic Diseases Information Reporting Management System (PDIRMS). The incidence and distribution of malaria were described in Jiangsu Province from 2015 to 2019. The distribution of three dimension, diagnostic institutions and diagnostic timeliness of imported malaria cases were described and analyzed. Results From 2015 to 2019, a total of 1 439 cases were reported in Jiangsu Province, of which 1 436 were imported cases, and 3 cases were blood transfusion infection cases. The reported cases were comprised of Plasmodium falciparum (1 075, 74.7%), Plasmodium vivax (63, 4.4%), Plasmodium ovale (233, 16.2%), Plasmodium malariae (65, 4.5%), and mixed infections (3, 0.2%). Imported malaria cases mainly came from Africa (97.5%, 1 400/1 436), Asia (1.9%, 28/1 436), South America and Oceania (0.6%, 8/1 436). The cases were reported from 13 cities in Jiangsu Province. The main imported malaria cases were young men aged 35-<50 years. In January, June and October, more cases were reported than other months. And 83.2% of the cases were diagnosed by medical institutions. The percentage of cases diagnosed by disease control agencies has decreased year by year ( P <0.05). The percentage of patients with more than 9 days time interval between onset and diagnosis in 2019 was significantly lower than that in the previous four years ( P <0.01). Conclusion Malaria epidemic situation in Jiangsu Province has been stable in recent five years. Most malaria cases are imported from abroad, a small part of malaria cases are infected by blood transfusion. The interval between onset and diagnosis is shorter. Prevention of the re-transmisson of imported malaria, improving the efficiency of diagnosis and treatment, and strengthen health education are very important for malaria prevention in Jiangsu Province. 摘要:目的 分析江苏省2015—2019年输人性疟疾疫情流行特征及诊断情况,为防止疟疾输人再传播,巩固消除 疟疾成果提供科学参考。 方法 疟疾疫情资料来自国家传染病监测系统和寄生虫病防治信息管理系统,采用流行病 学研究 方法 ,描述2015—2019年江苏省疟疾发病、感染来源和病例三间分布情况,对输人性疟疾病例的诊断以及发病 到诊断的时间间隔进行分析。 结果 2015—2019年,江苏省共报告1 439例疟疾病例,其中1 436例为境外输人病例,3例为输血感染病例。1 439例疟疾病例中,恶性疟1 075例（占74.7%)、间日疟63例（占4.4%)、卵形疟233例（占 16.2%)、三日疟65例（占4.5%)、同一时间发病的混合感染病例3例（占0.2%)。境外输人性疟疾病例中,1 400例来自非 洲（占97.5%),其他来自亚洲28例（占1.9%),以及南美洲和大洋洲8例（占0.6%)。江苏省13个设区市均有疟疾病例报 告;疟疾病例以35~<50岁男性青壮年居多,每年的1、6和10月出现病例报告髙峰。82.3%的病例由医疗机构诊断,由 疾控机构诊断的病例占比逐年降低( P <0.05)。2019年发病到确诊超过9 d的病人所占比明显低于前四年( P <0.01)。 结论 近5年江苏省疟疾疫情稳定,绝大部分为境外输人性病例,存在少数输血感染;病人就诊到确诊间隔时间有所缩 短。继续做好风险人群健康宣教,提髙医疗机构诊治能力,防止发生境外输人再传播,是今后疟疾防控工作的重点。

Reemergence of human malaria in Atlantic Forest of Rio Grande do Sul, Brazil.

Unforeseen Plasmodium infections in the Atlantic Forest of Brazilian Extra-Amazonian region could jeopardise malaria elimination. A human malaria case was registered in Três Forquilhas, in the Atlantic Forest biome of Rio Grande do Sul, after a 45 years’ time-lapsed without any malaria autochthonous notification in this southern Brazilian state. This finding represents the expansion of the malaria distribution areas in Brazil and the southernmost human malaria case record in South America in this decade. The coexistence of the bromeliad-breeding vector Anopheles (Kerteszia) cruzii and non-human primates in the Atlantic Forest regularly visited by the patient claimed for the zoonotic origin of this infection. The reemergence of Atlantic Forest human malaria in Rio Grande do Sul was also discussed.

Spatial distribution and sociodemographic risk factors of malaria in Nigerian children less than 5 years old.

Malaria remains a leading cause of morbidity and mortality among children in Nigeria less than 5 years old (under-5). This study utilized nationally representative secondary data extracted from the 2015 Nigeria Malaria Indicator Survey (NMIS) to investigate the spatial variability in malaria distribution in those under- 5 and to explore the influence of socioeconomic and demographic factors on malaria prevalence in this population group. To account for spatial correlation, a Spatially Generalized Linear Mixed Model (SGMM) was employed and predictive risk maps was developed using Kriging. Highly significant spatial variability in under-5 malaria distribution was observed (P<0.0001) with a higher likelihood of malaria prevalence in this group in the Northwest and North-east of the country. The number of malaria infections increased with age, children aged between 49-59 months were found to be at a higher risk (Odds Ratio=4.680, 95% CI=3.674 to 5.961 at P<0.0001). After accounting for spatial correlation, we observed a strong significant association between the non-availability or non-use of mosquito bed-nets, low household socioeconomic status, low level of mother's educational attainment, family size, anaemia prevalence, rural type of residence and under-5 malaria prevalence. Faced with a high rate of under-5 mortality due to malaria in Nigeria, targeted interventions (which requires the identification of the child's location) may reduce malaria prevalence, and we conclude that socioeconomic impediments need to be confronted to reduce the burden of childhood malaria infection.

Improving national level spatial mapping of malaria through alternative spatial and spatio-temporal models

The most common approach to create spatial prediction of malaria in the literature is to approximate a Gaussian process model using stochastic partial differential equation (SPDE). We compared SPDE to computationally faster alternatives, generalized additive model (GAM) and state-of-the-art machine learning method gradient boosted trees (GBM), with respect to their predictive skill for country-level malaria prevalence mapping. We also evaluated the intuition that incorporation of past data and the use of spatio-temporal models may improve predictive accuracy of present spatial distribution of malaria. Model performances varied among the countries and setting with SPDE and GAM performed well generally. The inclusion of past data is beneficial for GAM and GBM, but not for SPDE. We further investigated the weaknesses of SPDE at spatio-temporal setting and GAM at the edges of the countries. Taken together, we believe that spatial/spatio-temporal SPDE models should be evaluated alongside with the alternatives or at least GAM.

A study of malaria vector surveillance as part of the Malaria Elimination Demonstration Project in Mandla, Madhya Pradesh

BackgroundUnderstanding of malaria vector density, distribution, insecticide resistance, vector incrimination, infection status, and identification of sibling species are some of the essential components of vector control measures for achieving malaria elimination goals.MethodsAs part of the malaria elimination demonstration project, entomological surveillance was carried out from October 2017 to October 2019 by collecting indoor resting mosquitoes using hand catch method. Susceptibility test was done for determining the insecticide resistance status of vector mosquito Anopheles culicifacies using standard protocols by the World Health Organization. The cone bioassay method was used for determining the efficacy and quality of insecticide sprayed. Mosquitoes collected from different ecotypes were identified and processed for parasite identification, vector incrimination and sibling species determination.ResultsThe two known malaria vector species (Anopheles culicifacies and Anopheles fluviatilis) were found in the study area, which have been previously reported in this and adjoining areas of the State of Madhya Pradesh. The prevalence of An. culicifacies was significantly higher in all study villages with peak in July while lowest number was recorded in May. Proportion of vector density was observed to be low in foothill terrains. The other anopheline species viz, Anopheles subpictus, Anopheles annularis, Anopheles vagus, Anopheles splendidus, Anopheles pallidus, Anopheles nigerrimus and Anopheles barbirostris were also recorded in the study area, although their prevalence was significantly less compared to the An. culicifacies. In 2017, An. culicifacies was found to be resistant to dichloro-diphenyl-trichloroethane (DDT) and malathion, with possible resistance to alphacypermethrin and susceptible to deltamethrin. However, in 2019, the species was found to be resistant to alphacypermethrin, DDT, malathion, with possible resistance to deltamethrin. The bioassays revealed 82 to > 98% corrected % mortality of An. culicifacies on day-one post-spraying and 35 to 62% on follow-up day-30. Anopheles culicifacies sibling species C was most prevalent (38.5%) followed by A/D and E while B was least pre-dominant (11.9%). Anopheles fluviatilis sibling species T was most prevalent (74.6%) followed by U (25.4%) while species S was not recorded. One An.culicifacies (sibling species C) was found positive for Plasmodium falciparum by PCR tests in the mosquitoes sampled from the test areas.ConclusionBased on the nine entomologic investigations conducted between 2017–2019, it was concluded that An. culicifacies was present throughout the year while An. fluviatilis had seasonal presence in the study areas. Anopheles culicifacies was resistant to alphacypermethrin and emerging resistance to deltamethrin was observed in this area. Anopheles culicifacies was confirmed as the malaria vector. This type of information on indigenous malaria vectors and insecticide resistance is important in implementation of vector control through indoor residual spraying (IRS) and use of insecticide-impregnated bed nets for achieving the malaria elimination goals.

Geostatistical analysis and mapping of malaria risk in children of Mozambique.

Malaria remains one of the most prevalent infectious diseases in the tropics and subtropics, and Mozambique is not an exception. To design geographically targeted and effective intervention mechanisms of malaria, an up-to-date map that shows the spatial distribution of malaria is needed. This study analyzed 2018 Mozambique Malaria Indicator Survey using geostatistical methods to: i) explore individual, household, and community-level determinants of malaria in under-five children, ii) prepare a malaria prevalence map in Mozambique, and iii) produce prediction prevalence maps and exceedence probability across the country. The results show the overall weighted prevalence of malaria was 38.9% (N = 4347, with 95% CI: 36.9%-40.8%). Across different provinces of Mozambique, the prevalence of malaria ranges from 1% in Maputo city to 57.3% in Cabo Delgado province. Malaria prevalence was found to be higher in rural areas, increased with child's age, and decreased with household wealth index and mother's level of education. Given the high prevalence of childhood malaria observed in Mozambique there is an urgent need for effective public health interventions in malaria hot spot areas. The household determinants of malaria infection that are identified in this study as well as the maps of parasitaemia risk could be used by malaria control program implementers to define priority intervention areas.