Malaria Infection Rates Research Articles

Location and timing of infection drives a sex-bias in Haemoproteus prevalence in a hole-nesting bird.

Sex biases in prevalence of disease are often attributed to intrinsic factors, such as physiological differences while a proximate role of extrinsic factors such as behavioural or ecological differences may be more difficult to establish. We combined large-scale screening for the presence and lineage identity of avian malaria (haemosporidian) parasites, in 1234 collared flycatchers (Ficedula albicollis) with life-history information from each bird to establish the location and timing of infection. We found an overall infection rate of 36.2% ± 0.03 (95% CI) with 25 distinct malaria lineages. Interestingly, first-year breeding males and females had similar infection prevalence while females accrued a significantly higher infection rate than males later in life. The sex difference in infection rate was driven by the most abundant Haemoproteus, lineage, hPHSIB1, while the infection rate of Plasmodium lineages was similar in males and females. Furthermore, when infections were assigned to an apparent transmission location, we found that the sex difference in infection rate trend was driven by lineages transmitted in Europe, more specifically by one lineage (the hPHSIB1), while no similar pattern was found in African lineages. We deduce that the observed infection patterns are likely to be caused by differences in breeding behaviour, with incubating females (and nestling individuals of both sexes) being easy targets for the biting insects that are the vectors of avian malaria parasites. Overall, our results are most consistent with ecological factors rather than intrinsic factors underlying the observed sex-biased infection rate of avian malaria in collared flycatchers.

Seasonal Variation of Malaria Infections among Outpatients Attending Muhammad Abdullahi Wase Teaching Hospital Kano State, Nigeria

Malaria is a serious public health problem in Sub-saharan Africa including Nigeria, with the potential to increase significantly in response to seasonal changes. The aim of the study was to determine the influence of seasonal variations on the prevalence of malaria infection among outpatient attending Muhammad Abdullahi Wase teaching hospital Kano state, Nigeria. The objectives were to establishing the correlation between malaria infections and seasonal variations, and also determining the prevalence during different seasons, and evaluating the gender distribution of infection. The study was carried out from January to December, 2019, involving the use of microscopic examination of 840 blood samples using thick and thin film methods. Out of 840 patients examined (57.1%) had a malaria infection. Wet season had the highest prevalence rate of malaria infection (33.2%) than dry season (23.9%).There was a statistically significant differences (P<0.05) in the prevalence rate of malaria infection in relation to season. In relation to the gender females had higher (31.9%) prevalence rate of malaria infection than males (25.2%) and there was no significant difference in the prevalence rate of the infection in relation to sex (P>0.05). Concerning age groups, patients aged 26-30 years had the highest prevalence rate (9.04%), while those aged 40 and above had the lowest. However, the variation in prevalence among age groups was not statistically significant (P>0.05).This study confirmed that malaria infection still remains an important public health problem in the study area. Therefore, full implementation of adequate public health measures need to be undertaken to mitigate the endemicity of the disease, such as the Roll Back Malaria control Strategies as well as health education and environmental modifications are advocated is recommended.

Plasmodium Parasitaemia and Urine Alterations among Pregnant Women Attending Antenatal Care in Aba Metropolis, Abia State, Nigeria.

Malaria presents a huge threat to pregnant women, their foetus, and children below five years. This study is aimed at assessing malaria prevalence, associated clinical symptoms, and urine abnormalities among pregnant women in Aba metropolis, Abia State, Nigeria. A cross-sectional study involving 450 pregnant women purposively selected from nine health care centres was conducted. Data were analysed using SPSS version 26. The overall malaria prevalence rate was 68.4% (n = 308). Age group of 21-25 years had the highest prevalence rate of 20.4% (n = 92) while the least was recorded among the age group of 41-45 years (17 (3.8%)). Pregnant women in their first trimester had the greatest prevalence rate of 28.6% (n = 129), and the least prevalence was recorded among those in their third trimester (7 (15.6%)). The primigravidae were mostly infected at the rate of 27.7% (n = 125) whereas the multigravidae recorded the least prevalence of 85 (18.9%). Participants with secondary education were the most susceptible at the rate of 38.6% (n = 174). The infected participants exhibited significantly higher frequencies of reported fever (p > 0.001, OR 12.881, 95% CI 3.977-41.725) and headaches (p < 0.001, OR 4.688, 95% CI 1.819-12.083). However, cold, cough, body pains, poor appetite, and catarrh showed no significant association with malaria infection at p > 0.05. Participants using long-lasting insecticidal nets (LLINs) showed significantly lower prevalence rate of malaria infection (p < 0.001, OR 2.485, 95% CI 1.619-3.814). Malaria-infected participants showed statistically significant frequencies of proteinuria (p < 0.001, OR 274.14, 95% CI 16.91-4444.0), bilirubinuria (p < 0.001, OR 49.29, 95% CI 11.01-186.34), and urobilinogenuria (p < 0.001, OR 65.16, 95% CI 4.00-1062.40) than those not infected. Ascorbic acid, nitrate, and ketone showed no significant associations with malaria infection at p > 0.005. Infected participants had statistically significant amber and clear urine colour whereas there was no statistically significant difference between the pH levels of urine of the malaria-infected and malaria-noninfected pregnant women.

Co-infections of malaria and hepatitis B among pregnant women in Igbo-Eze North LGA of Enugu State, Nigeria

Acute hepatitis B virus (HBV) and malaria infections pose serious health risks to the general population and may worsen victims' physical and financial well-being. The objective of this study was to determine the frequency of HBV and malaria co-infections during LGA among expectant mothers. This study used a cross-sectional, prospective design. Blood samples were collected from both pregnant and non-pregnant women for parasitological and serological examinations in the study area. This was performed to compare the severity of infections between pregnant and non- pregnant women, as pregnant women are more susceptible to infections. The study included 50 women who attended antenatal care at the time of this project and 10 non-pregnant women who came to the hospitals for check-ups. Samples of people aged 18 to 52 years were collected. Age groups of 18-28 and 40-50 years had the greatest 30(50%) and lowest 8(13%) populations of women screened for malaria and hepatitis B co-infection, respectively. The 1st and 3rd trimesters were followed by the 2nd trimester, which had the highest prevalence. Only the second trimester had a 2% prevalence rate of hepatitis B. Farmers were the group most likely to contract malaria (92%). The percentage of government employees who had malaria and hepatitis B was the highest 20%), followed by traders (5%). Ogrute, the seat of the Local Government had a high rate of malaria infection despite having several medical facilities and less farming activities. Olido (25%), followed by Ogrute (14 point 3%), had the highest rate of co-infection with hepatitis B and malaria. The PCV ranges of 25–27(100%) and 28–30(100%) had the highest prevalence of malaria. This study shows how persistent malaria and hepatitis B are also associated with decreased packed cell volume (PCV) in pregnant women.

Use of Mapping Technologies to Study the Spatial Distribution of Malaria Incidence in Vietnam

Background: Malaria is one of the major public health issues globally. Malaria infection spreads through mosquito bites from infected female Anopheles mosquitoes. This study aims to apply mapping technologies to investigate the spatial distribution of malaria cases and incidence in Vietnam. Materials and Methods: Malaria cases in 2019 were first collected from the websites of the Vietnam Ministry of Health (VMH). The incidence of malaria will be then computed. The histogram is employed to study the distribution of malaria cases and incidence. Mapping technologies is then used to study the spatial distribution of malaria cases and incidence. In addition, a scatter plot is also used to investigate the relationship between population density and the incidence of malaria. Finally, results and findings will be discussed and summarised. Results: the study results showed that the highest rate of malaria infection was detected in Gia Lai, followed by Phu Yen, Dak Lak, and Binh Phuoc. Areas of high malaria infection rates were mainly concentrated in rural areas in the south-central region having with high vegetation coverage. Whereas, areas with no or low malaria infection rates were mainly concentrated in urban areas in the northeastern and southeastern regions of Vietnam. In addition, there was a negative correlation between population density and the incidence of malaria. Conclusion: It can be concluded that the combination of histograms, mapping technologies and a scatter plot prove their effectiveness in the study of malaria. Findings in this study provide an insight into how to apply mapping technologies to study and prevent the spread of such an infectious disease as malaria. Keywords: Spatial distribution, Malaria cases, Malaria incidence, Histogram, Scatter plot, Mapping technologies.

Paediatric Malaria: Associated Symptoms and Risk Factors among Children in Isheri, Alimosho Local Government Area, Lagos State, Nigeria

Malaria is a significant health issue, especially in tropical and subtropical regions. Children are particularly vulnerable to malaria due to their underdeveloped immune systems. Although many countries have implemented interventions to control and eliminate malaria, the disease remains a major public health challenge in endemic areas. This study is a cross-sectional survey conducted to determine the prevalence of paediatric malaria and identify associated risk factors in children under 5 years old at the Isheri Primary Health Centre in the Alimosho Local Government Area of Lagos State. The survey was carried out from June to September 2023. Blood samples were collected from 219 children, 44.7% male and 55.3% female. Parasitological analysis was conducted according to WHO standards, and data on associated risk factors and malaria prevention practices were collected through a pretested structured questionnaire. Statistical analyses such as T-test and One-way ANOVA were employed, with significance set at p&gt;0.05. The findings revealed an overall prevalence of paediatric malaria in the study location at 49.3% (n=108), with P. falciparum being the main parasite. Males had a 55.1% malaria infection rate, while females had a rate of 40.5%. All malaria-infected children tested positive for the asexual malaria parasite, with parasite density ranging from 2087 to 328000μL-1 and a mean value of 47267 — 80 (95% CI 35244-59292). Children &lt; 5years of age (55324 μL-1, 95% CI 29378-81271) had slightly higher asexual parasite density than those &gt; 5 years (44045μL-1, 95% CI 30440-576550). Haematological analysis showed that the infected children had a significantly higher count of neutrophils than the uninfected (p = 0.002). Furthermore, children who did not report experiencing fever and chills had a significantly higher parasite density than those who did (p&lt;0.05). The use of insecticide-treated bed nets (ITN) also had an impact, with children under 5 years of age not using ITNs having a higher parasite density (65390 μL-1, 95% CI 18219-112562) than those who did. The study also assessed environmental risk factors and found that stagnant water and poultry farms did not significantly impact the prevalence of paediatric malaria. The study concluded that improved access to malaria interventions is essential to interrupt transmission, particularly in the at-risk groups, to achieve the United Nations Sustainable Development Goals agenda for health.

Spatial variation and clustering of anaemia prevalence in school-aged children in Western Kenya.

Anaemia surveillance has overlooked school-aged children (SAC), hence information on this age group is scarce. This study examined the spatial variation of anaemia prevalence among SAC (5-14 years) in western Kenya, a region associated with high malaria infection rates. A total of 8051 SAC were examined from 82 schools across eight counties in Western Kenya in February 2022. Haemoglobin (Hb) concentrations were assessed at the school and village level and anaemia defined as Hb<11.5g/dl for age 5-11yrs and Hb <12.0g/dl for 12-14yrs after adjusting for altitude. Moran's I analysis was used to measure spatial autocorrelation, and local clusters of anaemia were mapped using spatial scan statistics and local indices of spatial association (LISA). The prevalence of anaemia among SAC was 27.8%. The spatial variation of anaemia was non-random, with Global Moran's I 0.2 (p-value < 0.002). Two significant anaemia cluster windows were identified: Cluster 1 (LLR = 38.9, RR = 1.4, prevalence = 32.0%) and cluster 2 (LLR = 23.6, RR = 1.6, prevalence = 45.5%) at schools and cluster 1 (LLR = 41.3, RR = 1.4, prevalence = 33.3%) and cluster 2 (LLR = 24.5, RR = 1.6, prevalence = 36.8%) at villages. Additionally, LISA analysis identified ten school catchments as anaemia hotspots corresponding geographically to SatScan clusters. Anaemia in the SAC is a public health problem in the Western region of Kenya with some localised areas presenting greater risk relative to others. Increasing coverage of interventions, geographically targeting the prevention of anaemia in the SAC, including malaria, is required to alleviate the burden among children attending school in Western Kenya.

Effects of Mobile Phone Tele-Reminder on the Prevalence of Malaria and Antenatal Care Satisfaction among Pregnant Women Availing Antenatal Care at Phebe and Charles B. Dunbar Hospitals, Bong County, Monrovia-Liberia A Cluster-Randomized Controlled Trial

Pregnant women with malaria and other associated infections have an increased risk of developing anemia later in pregnancy. This study aimed to determine the effect of mobile phone tele-reminder delivered through phone calls and SMS on the prevalence of malaria infection during pregnancy. The study recruited 150 pregnant women seeking antenatal care for the first time at the Phebe and Charles B. Dunbar hospitals in Bong County, Liberia. The antenatal care screening room (units of randomization) in both hospitals were randomized into six clusters. The 150 pregnant women were randomly assigned to an intervention group and a control group. A binary logistic regression using a generalized estimating equation model was run with a 95% Confidence Interval (CI). Malaria prevalence and antenatal care satisfaction were the primary outcome variables. The secondary outcome variable was the prevalence of anemia. Although there was a reduction in malaria infection in both groups, malaria prevalence between the intervention and control groups was not statistically significant (5 vs. 15%) (OR, 1.15; 95% CI, 0.71-1.85). Pregnant women in the intervention group were 4 times more likely to be very satisfied with ANC services compared with the control group (aOR, 4.01; 95%CI, 1.72-9.53). There was a positive trend toward anemia reduction among those in the intervention group. Integrating mobile phone technology in antenatal care services may help reduce the malaria infection rate and increase ANC satisfaction levels.

Plasmodium falciparum infection and naturally acquired immunity to malaria antigens among Ghanaian children in northern Ghana

BackgroundThe surge in malaria cases and deaths in recent years, particularly in Africa, despite the widespread implementation of malaria-control measures could be due to inefficiencies in malaria control and prevention measures in malaria-endemic communities. In this context, this study provides the malaria situation report among children in three Municipalities in Northern Ghana, where Seasonal Malaria Chemotherapy (SMC) is implemented by Ghana Health Service (GHS). MethodsA cross-sectional household survey was carried out to assess the malaria knowledge, attitudes, and practices (KAP) and malaria prevalence in 394 households in 13 rural communities in the Kumbugu, Nanton and Tolon Municipalities, Northern Region, Ghana. This was followed by screening for P. falciparum infection with anti-HRP2 RDT and PCR among children 1–17 years in the households. Plasma levels of IgG specific for crude P. falciparum antigen (3D7) and four recombinant malaria antigens (CSP, GLURP, MSP3, and Pfs230) were assessed by ELISA. The malaria and parasitaemia data were converted into frequency and subgroup proportions and disaggregated by study sites and demographic information of the participants. The ELISA data was converted to arbitrary units (AU) and similarly compared across study sites and demographic information. ResultsThe P. falciparum infection rate and frequency of malaria were high in the study areas with significant age-dependent and inter-community differences, which were reflected by differences in plasma levels of P. falciparum-specific IgG. Over 60% of households reported the use of bed nets and indoor insecticide sprays/coils, and 14% mentioned bush clearing around homes (14%) as malaria preventive measures. Community health centres were the preferred place for households (88%) to seek malaria treatment but over-the-counter drug stores were the major source (66%) of their antimalarials. Overall, malaria preventive and treatment practices were sub-optimal. ConclusionsP. falciparum infection and malaria are still high in the studied communities, indicating that preventive and control measures against the disease in the region remain inadequate. Efforts to ensure high SMC compliance and to improve preventative and treatment practices thus seem cost-beneficial “low-hanging fruits” in the fight against malaria in the Northern Region of Ghana.

Heme promotes sexual conversion of Plasmodium falciparum in human erythrocytes

Between 2018 and 2020, the global population experienced a 55% increase in deaths attributed to the most prominent malaria-causing pathogen, Plasmodium falciparum. Transmission of P. falciparum from a human host to the mosquito vector is completely reliant on the formation of sexual stage gametocytes, which arise from asexually replicating parasites during the intraerythrocytic stage of infection. Defining specific factors that promote the formation of transmissible sexual stages from the disease-causing asexual stages is important for developing new malaria control methods. Malaria infection rates are known to be affected by genetic variation of the hemoglobin (Hb) protein, and epidemiological studies have shown that Hb variants may positively influence the production of sexual stage parasites. However, the mechanisms involved are poorly defined. Here, we show P. falciparum sexual conversion rates (SCR) are significantly higher in erythrocytes expressing Hb S compared to those that express Hb A. We then found parasitic enzyme-mediated digestion of Hb S to occur more rapidly than Hb A, suggesting an increased release of heme groups carried by each Hb subunit. Upon manipulating both intracellular and extracellular heme concentrations, we found significant increases in SCR, ultimately indicating heme acts as an inducer of sexual conversion (SC). As levels of both intracellular and extracellular heme are increased in individuals with Hb variants, we propose heme to be a contributing factor for increased sexual stage conversion observed in these populations. These findings support further investigation into how heme concentrations may be directly manipulated to prevent commitment to sexual-stage formation and ultimately disease transmission.

Effects of Temperature and Nutrition during the Larval Period on Life History Traits in an Invasive Malaria Vector Anopheles stephensi.

Anopheles stephensi is an Asian and Middle Eastern malaria vector, and it has recently spread to the African continent. It is needed to measure how the malaria parasite infection in A. stephensi is influenced by environmental factors to predict its expansion in a new environment. Effects of temperature and food conditions during larval periods on larval mortality, larval period, female wing size, egg production, egg size, adult longevity, and malaria infection rate were studied using a laboratory strain. Larval survival and female wing size were generally reduced when reared at higher temperatures and with a low food supply during the larval period. Egg production was not significantly affected by temperature during the larval period. Egg size was generally smaller in females reared at higher temperatures during the larval period. The infection rate of mosquitoes that fed on blood from malaria-infected mice was not affected by rearing temperature or food conditions during the larval period. Higher temperatures may reduce infection. A. stephensi; however, larger individuals can still be infective. We suggest that routinely recording the body size of adults in field surveys is effective in finding productive larval breeding sites and in predicting malaria risk.

The association between female newborn and placental malaria infection: A case-control study

IntroductionThere are few published data on the influence of the sex of the fetus or the newborn on the rate of malaria infection. Moreover, the results of these studies are not conclusive. This study was conducted to investigate the association between sex of the newborn and placental malaria infection. MethodsA case-control study was conducted at Al Jabalian maternity hospital in central Sudan during the rainy and post rainy seasons from May to December 2020. The cases were women who had placental malaria, while the controls were subsequent women who had no placental malaria. A questionnaire was filled out by each woman in the case and control groups in order to gather demographic data as well as medical and obstetric history. Malaria was diagnosed using blood films. Logistic regression analyses were performed. ResultsThere were 678 women in each arm of the study. Compared with the women without placental malaria (controls), women with placental malaria had a significantly lower age and parity. A significantly higher number of the cases had delivered female newborns, 453 (66.8%) vs. 208 (30.7%), P < 0.001. In logistic regression, women with placental malaria: lived in rural areas, had low antenatal attendance, did not use bed nets, and had more female newborns (adjusted odds ratio, AOR = 2.90, 95% CI = 2.08–4.04). DiscussionWomen who delivered female were more likely to have placental malaria. Further research into the immunologic and biochemical parameters is warranted.

Study on the use and effectiveness of malaria preventive measures reported by employees of Chinese construction companies in Western Africa in 2021

BackgroundAs malaria continues to be a significant global public health concern, especially in Sub-Saharan Africa, Chinese workers in Africa are at increased risk of malaria. The effectiveness of malaria prevention measures implemented by Chinese companies and workers is a question that may correlate with the malaria infection rate in this population. This study explored the use and effectiveness of malaria prevention measures for Chinese employees in West Africa to provide a reference for companies and individuals on improving malaria prevention and control.MethodsUsing a cross-sectional approach, we surveyed 256 participants in 2021, mainly from Nigeria, Mali, Côte d’Ivoire, Ghana, Guinea, Sierra Leone, and Senegal in West Africa. The survey duration is from July to the end of September 2021. We selected two companies from the 2020 ENR "World’s Largest 250 International Contractors" list, which featured 6 Chinese companies, all of which are state-owned and have a 61.9% market share in Africa. The participants were Chinese workers with more than a year of work experience in construction companies in Africa. A 20-minute WeChat-based structured online questionnaire was used to obtain information on malaria infection status and malaria prevention measures. Descriptive statistical analysis, chi-square test, principal components analysis, and ordinal logistic regression analysis are used to analyze the data obtained. The difference in Statistical significance was set at P < 0.05.ResultsNinety six (37.5%) participants contracted malaria more than once within a year. The principal components analysis found a low correlation between public and individual preventive measures. No significant correlation was found between public preventive measures and malaria infection (p > 0.05), while standardized use of mosquito nets (P = 0.016) and pesticide spraying (P = 0.047) contributed significantly to fewer malaria infections at the individual level, but the removal of vegetation around houses (P = 0.028) at the individual level related to higher malaria infection.ConclusionsIn our sample of Chinese construction workers going to Africa, some individual preventive measures had a stronger association with malaria prevention than a variety of public environmental measures. Furthermore, individual and public preventive measures were not associated with each other. Both of these findings are surprising and require further investigation in larger and more diverse samples. This- study provides important clues about the challenges that risk reduction programs face for migrant workers from China and elsewhere.

Comparative Analytic Epidemiology of Plasmodium Parasitized Pregnant and Non-Pregnant Women Attending Tertiary Health Care Facility in Port Harcourt, Niger Delta

Malaria remains a public health burden in Nigeria. This study compared and determined the prevalence of malaria parasites and other possible risk factors among pregnant and non-pregnant women in Port Harcourt. A total of 200 blood samples (capillary) were collected from 100 pregnant and 100 non-pregnant women as a control through convenience sampling technique research design. The subjects for the study were drawn from women attending antenatal clinic in Braithwaite Memorial Hospital Port Harcourt, Rivers State, Nigeria. Thick and thin films were made on clean grease free glass slide and stained after drying with 3% solution of Giemsa stain to detect and identify the species of malaria parasites. SPSS version 21 was used to estimate frequency and percentage outcome. The results showed that out of 100 slides examined for pregnant women, 68% had malaria infection while 32% were negative. There were high prevalence rate of malaria infection among pregnant women of 20-23 years and 32-35 years age group while those ≥ 40 years showed least rate of 33%. The control samples showed infection rate of 71% with 29% negative. Showing that, non-pregnant women have a high prevalence rate when compared to pregnant women. It was discovered that illiterate pregnant women showed high prevalence rate than their educated counterparts. The use of indigenous (drug) herbs by some pregnant women proved 100% sensitive to P. falciparum as none were positive for malaria infection as captured through the administration of well-structured questionnaire. Intermittent treatment is therefore, recommended and further robust research should be channelled towards indigenous (drug) herbs for malaria treatment, especially in the developing communities. There is also urgent need for more inclusive malaria public health education in the region, especially among the vulnerable groups.

Impact of malaria control interventions on malaria infection and anaemia in low malaria transmission settings: a cross-sectional population-based study in Sudan.

The past two decades were associated with innovation and strengthening of malaria control interventions, which have been increasingly adopted at large scale. Impact evaluations of these interventions were mostly performed in moderate or high malaria transmission areas. This study aimed to evaluate the use and performance of malaria interventions in low transmission areas on malaria infections and anaemia. Data from the 2016 Sudan malaria indicator survey was used. Multi-level logistic regression analysis was used to assess the strength of association between real-life community-level utilization of malaria interventions [diagnosis, artemisinin-based combination therapies (ACTs) and long-lasting insecticidal nets (LLINs)] and the study outcomes: malaria infections and anaemia (both overall and moderate-to-severe anaemia). The study analysis involved 26,469 individuals over 242 clusters. Malaria infection rate was 7.6%, overall anaemia prevalence was 47.5% and moderate-to-severe anaemia prevalence was 4.5%. The average community-level utilization was 31.5% for malaria diagnosis, 29.9% for ACTs and 35.7% for LLINs. The odds of malaria infection was significantly reduced by 14% for each 10% increase in the utilization of malaria diagnosis (adjusted odds ratio (aOR) per 10% utilization 0.86, 95% CI 0.78-0.95, p = 0.004). However, the odds of infection was positively associated with the utilization of LLINs at community-level (aOR per 10% utilization 1.20, 95% CI 1.11-1.29, p < 0.001). No association between malaria infection and utilization of ACTs was identified (aOR per 10% utilization 0.97, 95% CI 0.91-1.04, p = 0.413). None of the interventions was associated with overall anaemia nor moderate-to-severe anaemia. There was strong evidence that utilization of malaria diagnosis at the community level was highly protective against malaria infection. No protective effect was seen for community utilization of ACTs or LLINs. No association was established between any of the interventions and overall anaemia or moderate-to-severe anaemia. This lack of effectiveness could be due to the low utilization of interventions or the low level of malaria transmission in the study area. Identification and response to barriers of access and low utilization of malaria interventions are crucial. It is crucial to ensure that every suspected malaria case is tested in a timely way, notably in low transmission settings.

A mass rearing cost calculator for the control of Culex quinquefasciatus in Hawaiʻi using the incompatible insect technique

BackgroundHawaiʻi’s native forest avifauna is experiencing drastic declines due to climate change-induced increases in temperature encroaching on their upper-elevation montane rainforest refugia. Higher temperatures support greater avian malaria infection rates due to greater densities of its primary vector, the southern house mosquito Culex quinquefasciatus, and enhance development of the avian malaria parasite Plasmodium relictum. Here we propose the use of the incompatible insect technique (IIT) or the combined IIT/sterile insect technique (SIT) for the landscape-scale (i.e., area-wide) control of Cx. quinquefasciatus, and have developed a calculator to estimate the costs of IIT and IIT/SIT applications at various sites in Hawaiʻi.MethodsThe overall cost of the infrastructure, personnel, and space necessary to produce incompatible adult males for release is calculated in a unit of ~ 1 million culicid larvae/week. We assessed the rearing costs and need for effective control at various elevations in Hawaiʻi using a 10:1 overflooding ratio at each elevation. The calculator uses a rate describing the number of culicids needed to control wild-type mosquitoes at each site/elevation, in relation to the number of larval rearing units. This rate is a constant from which other costs are quantified. With minor modifications, the calculator described here can be applied to other areas, mosquito species, and similar techniques. To test the robustness of our calculator, the Kauaʻi-specific culicid IIT/SIT infrastructure costs were also compared to costs from Singapore, Mexico, and China using the yearly cost of control per hectare, and purchasing power parity between sites for the cost of 1000 IIT/SIT males.ResultsAs a proof of concept, we have used the calculator to estimate rearing infrastructure costs for an application of IIT in the Alakaʻi Wilderness Reserve on the island of Kauaʻi. Our analysis estimated an initial investment of at least ~ $1.16M with subsequent yearly costs of approximately $376K. Projections of rearing costs for control at lower elevations are ~ 100 times greater than in upper elevation forest bird refugia. These results are relatively comparable to those real-world cost estimates developed for IIT/SIT culicid male production in other countries when inflation and purchasing power parity are considered. We also present supplemental examples of infrastructure costs needed to control Cx. quinquefasciatus in the home range of ʻiʻiwi Drepanis coccinea, and the yellow fever vector Aedes aegypti.ConclusionsOur cost calculator can be used to effectively estimate the mass rearing cost of an IIT/SIT program. Therefore, the linear relationship of rearing infrastructure to costs used in this calculator is useful for developing a conservative cost estimate for IIT/SIT culicid mass rearing infrastructure. These mass rearing cost estimates vary based on the density of the targeted organism at the application site.Graphic

Risk factors and housing effect on malaria infection: A case-control study

Background: This study aims to demonstrate the different risk factors between low and high endemicity area and housing effect on malaria infection. Methods: This study is a case-control study with a ratio of 1:2 comparing low (Jambi) and high (Sumba) endemicity areas. Initial screening of malaria was done to assign cases and controls following inclusion criteria. The selected cases and controls were then assessed with a structured questionnaire in relation to risk factors of malaria infection. Additionally, to discover the impact of house type on malaria infection, a total of 72 houses was observed in a series of six weeks (between 28 June and 12 August 2018) human landing catch (HLC) observations that includes three types of houses; malaria, non-malaria, and permanent dwellings. The HLC was done indoors and outdoors for each house type each night. A weekly screening was taken to monitor the malaria infection rate of each house type. Results: Jambi and Sumba shared several similar individual and environmental risk factors. However, agricultural activity or visiting forestry areas is a protective factor for malaria infection in Jambi but is a risk factor in Sumba. The general linear mixed univariate model result indicates the difference in risk factor variables between Jambi and Sumba. The entomological survey found that only malaria houses significantly differed in the number of means collected mosquitoes compared with the other type of houses. Weekly screening found that the incidence rate of malaria houses is highest among others. Conclusion: The risk factors are inevitably crucial for malaria prevention strategy. Risk factor management needs to consider the location where the endemicity level may differ for each risk factor, and housing improvement is not a proper strategy before controlling other environmental factors.

Malaria in pregnancy control and pregnancy outcomes: a decade’s overview using Ghana’s DHIMS II data

BackgroundMalaria in pregnancy control interventions have been implemented through antenatal care services for more than 2 decades in Ghana. The uptake of these interventions has seen steady improvement over the years. This has occurred within the context of decreasing global trends of malaria infection confirmed by decreasing malaria in pregnancy prevalence in Ghana. However, not much is known about how these improvements in interventions uptake and reduction in malaria infection prevalence have impacted pregnancy outcomes in the country. This study aimed at describing trends of maternal anaemia and low birth weight prevalence and uptake of malaria in pregnancy control interventions over the last decade using data from Ghana’s District Health Information Management System (DHIMS II).MethodsData from Ghana’s DHIMS II on variables of interest covering the period 2012 to 2021 was analysed descriptively using Microsoft Excel 365. Results were computed as averages and percentages and presented in tables and graphs.ResultsThe prevalence of maternal anaemia at booking and at term and low birth weight increased marginally from 31.0%, 25.5% and 8.5% in 2012 to 36.6%, 31.9% and 9.5% in 2021 respectively. Severe anaemia prevalence at booking and at term remained under 2% over the study period. Women making at least 4 ANC visits, receiving at least 3 doses of intermittent preventive treatment of malaria and an insecticide-treated net increased from 77.0%, 41.4% and 4.1% in 2012 to 82%, 55.0% and 93.3% in 2021, respectively. Malaria test positivity rate reduced from 54.0% to 34.3% between 2014 and 2021 while women receiving iron and folate supplementation for 3 and 6 months rose from 43.0% and 25.5% to 89.7% and 61.8%, respectively between 2017 and 2021.ConclusionMaternal anaemia and low birth weight prevalence showed marginal upward trends over the last decade despite reduced malaria infection rate and improved uptake of malaria in pregnancy control interventions. There is room for improvement in current intervention implementation levels but the complex and multi-factorial aetiologies of maternal anaemia and low birth weight need urgent investigation and quantification to inform policy and practice.

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.

Predicting malaria outbreaks from sea surface temperature variability up to 9 months ahead in Limpopo, South Africa, using machine learning.

Malaria is the cause of nearly half a million deaths worldwide each year, posing a great socioeconomic burden. Despite recent progress in understanding the influence of climate on malaria infection rates, climatic sources of predictability remain poorly understood and underexploited. Local weather variability alone provides predictive power at short lead times of 1–2 months, too short to adequately plan intervention measures. Here, we show that tropical climatic variability and associated sea surface temperature over the Pacific and Indian Oceans are valuable for predicting malaria in Limpopo, South Africa, up to three seasons ahead. Climatic precursors of malaria outbreaks are first identified via lag-regression analysis of climate data obtained from reanalysis and observational datasets with respect to the monthly malaria case count data provided from 1998–2020 by the Malaria Institute in Tzaneen, South Africa. Out of 11 sea surface temperature sectors analyzed, two regions, the Indian Ocean and western Pacific Ocean regions, emerge as the most robust precursors. The predictive value of these precursors is demonstrated by training a suite of machine-learning classification models to predict whether malaria case counts are above or below the median historical levels and assessing their skills in providing early warning predictions of malaria incidence with lead times ranging from 1 month to a year. Through the development of this prediction system, we find that past information about SST over the western Pacific Ocean offers impressive prediction skills (~80% accuracy) for up to three seasons (9 months) ahead. SST variability over the tropical Indian Ocean is also found to provide good skills up to two seasons (6 months) ahead. This outcome represents an extension of the effective prediction lead time by about one to two seasons compared to previous prediction systems that were more computationally costly compared to the machine learning techniques used in the current study. It also demonstrates the value of climatic information and the prediction framework developed herein for the early planning of interventions against malaria outbreaks.