Assessment of risk factors associated with malaria transmission in tubu village, northern botswana

Malaria Prevalence and Risk Factors in Outpatients at Teda Health Center, Northwest Ethiopia: A Cross-Sectional Study

Background

Despite extensive efforts and achievements made in prevention and control, malaria is still a public health problem in Ethiopia. Currently, the case number has been climbing, even changing the epidemiology to the previously low-burden reporting locations. Therefore, our study is aimed at assessing malaria prevalence and associated risk factors in outpatients, Northwest Ethiopia.

Methods

A facility-based cross-sectional study was conducted among 318 malaria-suspected outpatients from October 22 to December 15, 2022, at Teda Health Center, Northwest Ethiopia. Sociodemographic characteristics and malaria risk factors were assessed by a face-to-face interview using a pretested questionnaire. Plasmodium parasites were detected by using microscopy on a blood film stained with 10% and 3% Giemsa stain. The data were analyzed using Statistical Package for Social Sciences software version 25, and statistical significance was reported at a p value < 0.05.

Results

Of the 318 study participants, 124 (39.0%; 95%CI = 33.6% - 44.6%) tested positive for Plasmodium infection. Plasmodium vivax, P. falciparum, and mixed infections were identified in 71 (57.3%), 47 (37.9%), and 6 (4.8%), respectively, among positive study participants. Individuals above the age of 15 (AOR = 2.704, 95% CI 1.370-5.336) were more likely to be infected with Plasmodium than under-five-year-old individuals. Rural residents (AOR = 2.56, 95% CI 1.281-5.098), those who sleep or work outside at night (AOR = 1.99, 95% CI 1.020-3.875), and individuals who did not use long-lasting insecticide-treated net (AOR = 3.26, 95% CI 1.633-6.499) and had a family member with a history of malaria (AOR = 2.902, 95%CI = 1.671 - 5.041) had higher odds of acquiring Plasmodium infection than their counterparts.

Conclusion

In our study area, malaria was a major health problem, with P. vivax being the dominant species. Multiple environmental and behavioural factors were associated with the infection acquisition. Therefore, urgent holistic intervention is required.

Community Knowledge, Perceptions and Experiences on Healthcare Services for Malaria Prevention and Treatment in the Okavango Delta, Botswana

This paper analyses community knowledge, perceptions, and experiences of effectiveness of healthcare service provision on malaria prevention/treatment in two disease-endemic villages of the Okavango Delta panhandle in northern Botswana. A stratified random sampling of 355 households was conducted in October-November 2015. Follow-up retrospective cohort interviews were undertaken in August 2016 from 79 households that reported malaria incidences during the household survey. Data were also collected from 16 key informant interviews and 2 focus group discussions participants. Descriptive statistics and content analyses were used to summarise quantitative and qualitative data, respectively. Results indicate that communities in the study sites had positive perceptions about efficiency of health services based on availability, accessibility and utilization, adequacy of prevention and treatment interventions. Local health clinics were crucial information channels used by respondents. Additionally, factors related to acceptability, availability and accessibility are likely to contribute to perceived effectiveness of the interventions provided by healthcare service providers. Affirmation of efficiency health service provision against malaria has public health implications for adherence to treatment/prevention and participation in community health education campaigns and program implementation in the Okavango Delta region.

Occurrence of asymptomatic malaria infection and living conditions in the lowlands of Ethiopia: a community-based cross-sectional study

Background

A significant decline in malaria burden was documented in previously high burden African countries. Even though the global decline in malaria burden is significant, about 95% of it was typically found in 29 African countries and the decline was affected by COVID-19 in 2020. The considerable reduction in malaria incidence was noted due to effective prevention and treatment efforts, and rapid changes in living conditions. The relationship between the occurrence of asymptomatic malaria infection and household living conditions is well unstudied. This study aimed to determine the association between household living conditions and the occurrence of asymptomatic malaria in the lowlands of Ethiopia.

Methods

A community-based cross-sectional study was conducted from January to March 2021 in twelve villages of Gambella, Southern Nation Nationalities and People Region and Afar in Ethiopia. A total of 1366 households were randomly selected, interviewed, and tested for malaria by rapid diagnostic test and blood film microscopic examination. Multiple logistic regression model was used to determine the independent association between living conditions and asymptomatic malaria infection.

Results

The prevalence of asymptomatic malaria infection among individuals living in dwellings built with traditional floor/wall/roof ranges from 8.1% to 8.4% while it ranges from 2.0% to 4.6% among those living in modern floor/wall/roof houses. Dwellings built with traditional wall materials (P = 0.050), spending nights with cattle in the same house (P < 0.001), and availability of kitchen in the main house with no partition (P = 0.004) were significantly associated with asymptomatic malaria infection.

Conclusions

Asymptomatic malaria infection was 4.3 times higher among occupants residing in dwellings built with traditional wall materials; 5.6 times higher among households spending nights with cattle in the same house, and 2.3 times higher among households with kitchen in the main house with no partition. Therefore, policies and strategies on malaria elimination need to address or target improvements of the above listed living conditions for the community. A multi sectoral action is required to use these social determinants as a vector control strategic addition; and malaria elimination programs are expected to coordinate the implementation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-022-01018-3.

Five-Year Trend of Malaria Prevalence in Mojo Town, Central Ethiopia: Shifting Burden of the Disease and Its Implication for Malaria Elimination: A Retrospective Study

Introduction

Malaria continues to strike hardest against the health and economic development in Ethiopia. The peak of malaria incidence follows the main rainfall season in each year; however, its transmission tends to be highly heterogeneous within or between years and from area to area. Thus, this study was aimed to determine the trend prevalence of malaria in Mojo town, central Ethiopia.

Methods

A retrospective study was conducted in Mojo town, East Shoa zone, Ethiopia from February to March 2021. Malaria cases and related data documented between 2016 and 2020 were carefully reviewed from laboratory registration logbooks. The collected data were analyzed using descriptive statistics.

Results

A total of 19,106 blood films were examined from malaria-suspected patients. The overall microscopically confirmed prevalence of malaria was 4.2% (793/19,106). Plasmodium vivax was the predominant species accounting for 76.2% (604/793) of positive samples. Malaria cases declined from 259 in 2016 to 77 in 2020. The proportion of malaria was higher among males (64.8%, 514/793) than females (35.2%, 279/793) (P < 0.0001). Higher malaria cases were observed from the age group 15–24 years followed by the age group of 25–34 (P < 0.0001). The number of malaria cases was at a high level from September to November and lowest from December to February.

Conclusion

Despite a declining trend of malaria prevalence, it remains a public health burden in the area. P. vivax, the predominant species, should get attention during prevention and control strategies for the successful progress of the malaria elimination program.

Malaria infection and anemia status in under-five children from Southern Tanzania where seasonal malaria chemoprevention is being implemented

Background

Malaria and anemia remain major public health challenges in Tanzania. Household socioeconomic factors are known to influence these conditions. However, it is not clear how these factors influence malaria transmission and anemia in Masasi and Nanyumbu Districts. This study presents findings on malaria and anemia situation in under-five children and its influencing socioeconomic factors in Masasi and Nanyumbu Districts, surveyed as part of an ongoing seasonal malaria chemoprevention operational study.

Methods

A community-based cross-sectional survey was conducted between August and September 2020. Finger-prick blood samples collected from children aged 3–59 months were used to test for malaria infection using malaria rapid diagnostic test (mRDT), thick smears for determination of asexual and sexual parasitemia, and thin smear for parasite speciation. Hemoglobin concentration was measured using a HemoCue spectrophotometer. A structured questionnaire was used to collect household socioeconomic information from parents/caregivers of screened children. The prevalence of malaria was the primary outcome. Chi-square tests, t-tests, and logistic regression models were used appropriately.

Results

Overall mRDT-based malaria prevalence was 15.9% (373/2340), and was significantly higher in Nanyumbu (23.7% (167/705) than Masasi District (12.6% (206/1635), p<0.001. Location (Nanyumbu), no formal education, household number of people, household number of under-fives, not having a bed net, thatched roof, open/partially open eave, sand/soil floor, and low socioeconomic status were major risks for malaria infection. Some 53.9% (1196/2218) children had anemia, and the majority were in Nanyumbu (63.5% (458/705), p<0.001. Location (Nanyumbu), mRDT positive, not owning a bed net, not sleeping under bed net, open/partially open eave, thatched window, sex of the child, and age of the child were major risk factors for anemia.

Conclusion

Prevalence of malaria and anemia was high and was strongly associated with household socioeconomic factors. Improving household socioeconomic status is expected to reduce the prevalence of the conditions in the area.

Malaria Infection is High at Transit and Destination Phases Among Seasonal Migrant Workers in Development Corridors of Northwest Ethiopia: A Repeated Cross-Sectional Study

Purpose

Malaria is a leading public health problem in Ethiopia. Every year, thousands of seasonal farm workers travel to farm corridors in Northwest Ethiopia and fall at risk of malaria infection. However, the magnitude of malaria infection and risk factors during harvest time were not well identified. This study aimed at estimating the prevalence and risk factors of malaria infection among seasonal migrant workers in Northwest Ethiopia.

Methods

A repeated cross-sectional study was conducted at transit and destination phases in Metema district from September 15, 2018 to October 30, 2019. Data were collected using a structured questionnaire. A capillary blood sample was collected to examine infection with malaria parasite using a microscope. A multivariate logistic regression technique was used to determine risk factors.

Results

The malaria prevalence at transit and destination phases among migrant workers was 13.5% (95% CI: 12.07–14.93%) and 18.7% (95% CI: 16.40–21.02%), respectively. The combined prevalence was 16.1% (95% CI: 14.67–17.63%). The odds of malaria infection among migrant workers at the destination phase was 1.5 (OR=1.5, 95% CI 1.167–1.846) times higher compared to the transit phase. Education (AOR=8.198; 95% CI: 4.318–15.564), knowledge of antimalarial drugs (AOR=2.4; 95% CI: 1.43–3.95), and use of long-lasting insecticidal nets (AOR=5.0; 95% CI: 3.34–4.43) were significantly associated with malaria infection at migration phases.

Conclusion

This study showed that the burden of malaria among seasonal migrant workers was high at transit and destination phases. Malaria prevalence was higher at the destination phase compared to the transit phase. A tailored malaria prevention intervention is needed including awareness creation, screening, treatment, repellent, and prophylaxis at both phases to reduce malaria infections.

Malaria Diagnosed in an Urban Setting Strongly Associated with Recent Overnight Travel: A Case-Control Study from Kampala, Uganda

Malaria is frequently diagnosed in urban Kampala, despite low transmission intensity. To evaluate the association between recent travel out of Kampala and malaria, we conducted a matched case-control study. Cases were febrile outpatients with a positive malaria test; controls were febrile outpatients with a negative test. For every two cases, five controls were selected, matching on age. Data were collected on recent overnight travel out of Kampala (past 60 days), destination and duration of travel, and behavioral factors, including sleeping under an insecticide-treated net (ITN) during travel. From July to August 2019, 162 cases and 405 controls were enrolled. The locations of residence of cases and controls were similar. More controls were female (62.7% versus 46.3%, P < 0.001). Overall, 158 (27.9%) participants reported recent overnight travel. Travelers were far more likely to be diagnosed with malaria than those who did not travel (80.4% versus 8.6%, OR 58.9, 95% CI: 23.1-150.1, P < 0.001). Among travelers, traveling to a district not receiving indoor residual spraying of insecticide (OR 35.0, 95% CI: 4.80-254.9, P < 0.001), no ITN use (OR 30.1, 95% CI: 6.37-142.7, P < 0.001), engaging in outdoor activities (OR 22.0, 95% CI: 3.42-141.8, P = 0.001), and age < 16 years (OR 8.36, 95% CI: 2.22-56.2, P = 0.03) were associated with increased odds of malaria. Kampala residents who traveled overnight out of the city were at substantially higher risk of malaria than those who did not travel. For these travelers, personal protection measures, including sleeping under an ITN when traveling, should be advocated.

Are Vulnerable Communities Thoroughly Informed on Mosquito Bio-Ecology and Burden?

Mosquitoes account for a significant burden of morbidity and mortality globally. Despite evidence of (1) imminent anthropogenic climate and environmental changes, (2) vector-pathogen spatio-temporal dynamics and (3) emerging and re-emerging mosquito borne infections, public knowledge on mosquito bio-ecology remain scant. In particular, knowledge, attitude and practices (KAPs) on mosquitoes are often neglected despite otherwise expensive remedial efforts against consequent infections and other indirect effects associated with disease burden. To gather baseline KAPs that identify gaps for optimising vector-borne disease control, we surveyed communities across endemic and non-endemic malaria sub-districts (Botswana). The study revealed limited knowledge of mosquitoes and their infections uniformly across endemic and non-endemic areas. In addition, a significant proportion of respondents were concerned about mosquito burdens, although their level of personal, indoor and environmental protection practices varied significantly across sub-districts. Given the limited knowledge displayed by the communities, this study facilitates bridging KAP gaps to minimise disease burdens by strengthening public education. Furthermore, it provides a baseline for future studies in mosquito bio-ecology and desirable control practices across differential spheres of the rural-urban lifestyle, with implications for enhanced livelihoods as a consequence of improved public health.

Past and current biological factors affecting malaria in the low transmission setting of Botswana: A review

Malaria continues to be one of the top infectious agents contributing to morbidity and mortality in sub-Saharan Africa. Annually, Botswana accounts only for a small proportion of cases (<<1%). Despite significantly reduced incidence rate, the country still experiences sporadic outbreaks that hamper the goal of malaria elimination. This review evaluated previous and current biological factors that impact malaria in Botswana, specifically focussing on the vectors, the parasite and the host. This was accomplished via a literature review evaluating these variables in Botswana. Current literature suggests that Anopheles arabiensis is the main malaria vector in the country. Several other potential vectors have been found widely distributed throughout Botswana in high numbers, yet remain largely unstudied with regards to their contribution to the country's malaria burden. We also report the most up to date list of all Anopheles species that have been found in Botswana. Plasmodium falciparum is responsible for the vast majority of symptomatic malaria in the country and some drug resistance markers have been documented for this species. Plasmodium vivax has been reported in asymptomatic subjects, even though a large proportion of the Botswana population appears to be Duffy antigen negative. Very little is known about the true distribution of P. vivax and no point of care testing infrastructure for this species exists in Botswana, making it difficult to tailor treatment to address possible recrudescence or relapse. Due to a genetically diverse population with a substantial Khoisan contribution into the Bantu genetic background, several phenotypes that potentially impact prevalence and severity of malaria exist within the country. These include sickle cell trait, Glucose-6-Phosphate Dehydrogenase deficiency, and Duffy negativity. This review highlights the information that currently exists on malaria in Botswana. It also postulates that a comprehensive understanding of these aforementioned biological factors may help to explain malaria persistence in Botswana.

Travel Is a Key Risk Factor for Malaria Transmission in Pre-Elimination Settings in Sub-Saharan Africa: A Review of the Literature and Meta-Analysis

By sustaining transmission or causing malaria outbreaks, imported malaria undermines malaria elimination efforts. Few studies have examined the impact of travel on malaria epidemiology. We conducted a literature review and meta-analysis of studies investigating travel as a risk factor for malaria infection in sub-Saharan Africa using PubMed. We identified 22 studies and calculated a random-effects meta-analysis pooled odds ratio (OR) of 3.77 (95% CI: 2.49–5.70), indicating that travel is a significant risk factor for malaria infection. Odds ratios were particularly high in urban locations when travel was to rural areas, to more endemic/high transmission areas, and in young children. Although there was substantial heterogeneity in the magnitude of association across the studies, the pooled estimate and directional consistency support travel as an important risk factor for malaria infection.

Large Variations in Malaria Parasite Carriage by Afebrile School Children Living in Nearby Communities in the Central Region of Ghana

Background

Indicators of successful malaria control interventions include a reduction in the prevalence and densities of malaria parasites contained in both symptomatic and asymptomatic infections as well as a reduction in malaria transmission. Individuals harboring malaria parasites in asymptomatic infections serve as reservoirs for malaria transmission. This study determined the prevalence of asymptomatic malaria parasite carriage in afebrile children attending six different schools in two districts, the Cape Coast Metropolitan Assembly (CCMA) and the Komenda Edina Eguafo Abirem (KEEA) of the Central Region of Ghana.

Methods

This cross sectional study recruited afebrile children aged between 3 and 15 years old from six randomly selected schools in the Central Region of Ghana. Finger-pricked blood was collected and used to prepare thick and thin blood smears as well as spot a strip of filter paper (Whatman #3). Nested PCR was used to identify Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale, and Plasmodium vivax in DNA extracted from the filter paper spots. The multiplicity of P. falciparum infection was determined using merozoite surface protein 2 genotyping.

Results

Out of the 528 children sampled, PCR identified 27.1% to harbor Plasmodium parasites in asymptomatic infections, whilst microscopy identified malaria parasites in 10.6% of the children. The overall PCR estimated prevalence of P. falciparum and P. malariae was 26.6% and 1.3%, respectively, with no P. ovale or P. vivax identified by PCR or microscopy. The RDT positivity rate ranged from 55.8% in Simiw to 4.5% in Kuful. Children from the Simiw Basic School accounted for 87.5% of all the asymptomatic infections. The multiplicity of P. falciparum infection was predominantly monoclonal and biclonal.

Conclusions

The low prevalence of asymptomatic malaria parasite carriage by the children living in the Cape Coast Metropolis suggests that the malaria control interventions in place in CCMA are highly effective and that additional malaria control interventions are required for the KEEA district to reduce the prevalence of asymptomatic malaria parasite carriers. No molecular evidence of P. ovale and P. vivax was identified in the afebrile children sampled from the selected schools.

Malaria Risk Factors in Banjarnegara, Indonesia: A Matched Case-Control Study

Malaria is a matter of concern in public health worldwide. Identifying its risk factors is essential to determine control efforts. We studied the potential environmental and human behaviour risk factors in malaria by a matched case-control study conducted in the Banjarmangu I Public Health Centre area, Banjarnegara, from June to August 2018. A structured questionnaire and checklist were employed to collect data from 50 participants. Data were analysed by Chi-Square, Fisher exact and logistic regression. A positive association was found between malaria and not sleeping under bed mosquito netting (OR=2.087 [95% CI: 1.148 - 3.795]), not using wire netting in the house ventilation (OR = 3.907 [95% CI: 0.647 - 24.452]), and inadequate prevention practices during outdoor activities (OR = 2.020 [95% CI: 1.033 - 3.953]). These three factors were identified as independent risk factors for malaria.

Association Between Recent Overnight Travel and Risk of Malaria: A Prospective Cohort Study at 3 Sites in Uganda

Background

Human movement can undermine malaria control efforts. However, understanding of the association between travel and malaria infection in Africa is limited. We evaluated the association between recent overnight travel and malaria incidence in Uganda.

Methods

All children aged 0.5-10 years and 1 adult living in 266 randomly selected households within 3 different regions of Uganda were followed up prospectively. Information on overnight travel was collected in 2015-2016. Malaria, defined as fever with parasites detected by microscopy, was measured using passive surveillance.

Results

At least 1 overnight trip was reported by 64 of 275 (23.3%) participants in Walukuba, 37 of 317 (11.7%) in Nagongera, and 19 of 314 (6.1%) in Kihihi. Among individuals who traveled, the incidence of malaria was higher in the first 60 days after traveling, compared with periods without recent travel at all 3 sites (overall, 1.15 vs 0.33 episodes per person-year; incidence rate ratio, 3.53; 95% confidence interval, 1.85-6.73; P < .001). Risk factors for malaria within 60 days after overnight travel included young age (19.5% in children vs 4.9% in adults; odds ratio, 5.29; 95% confidence interval, 1.34-21.0; P = .02) and not using an insecticide-treated net during travel (18.0% for no use vs 4.1% for any use; 5.10; 1.07-24.5; P = .04).

Conclusions

Recent overnight travel was associated with a higher incidence of malaria. Individuals who travel may represent a high-risk group that could be targeted for malaria control interventions, particularly use of insecticide-treated nets.

Clinical features and haematological parameters among malaria patients in Mangaluru city area in the southwestern coastal region of India

The aim of this study was to assess the clinical profile, severity and complications of patients suffering from malaria in Mangaluru, a southwestern coastal city in India. A total of 579 patients, who were treated at the District Wenlock Hospital, Mangaluru, and 168 healthy controls were recruited in this study. The clinical profile, haematological and biochemical parameters, and disease complications were assessed. The majority of patients were treated as outpatients and patients who had severe clinical conditions were admitted to the hospital for treatment and supportive care. Among the total 579 patients recruited in this study, the distribution of P. vivax, P. falciparum and mixed infections were 364 (62.9%), 150 (25.9%) and 65 (11.2%), respectively. Among these, 506 (87.4%) had mild malaria, whereas 73 (12.6%) had severe malaria. Overall, the clinical features and severity of malaria in P. vivax and mixed infection patients were comparable to P. falciparum patients, albeit with some significant differences. The clinical complications in severe malaria cases included thrombocytopenia (50.7%), metabolic acidosis (30.1%), severe anaemia (26.0%), jaundice (21.9%), hepatic dysfunction (15.1%), acute renal failure (6.8%), haematuria (8.2%), hypotension (9.6%), cerebral malaria (1.4%) and acute respiratory distress syndrome (1.4%). All the patients with severe malaria recruited in our study were successfully treated and discharged. Majority of patients had mild malaria, likely due to seeking treatment soon after experiencing symptoms and/or having preexisting immune protection. However, a significant number of patients had severe malaria and required hospital admission indicating that there is a substantial need for creating awareness among vulnerable immigrant population. Implementing effective surveillance and vector control measures in malaria hotspot locations in the city and educating people about preventive measures are likely to reduce the malaria burden in this endemic region.

Evaluating a 24-h mobile reporting system for malaria notifications in comparison with a paper-based system in South Africa, 2015

BACKGROUND

As South Africa strives to achieve malaria elimination by 2018 (zero local cases) the country needs to strengthen its disease surveillance system by reducing the timeliness from case diagnosis to notification of key stakeholders in the malaria programme. This study evaluated the feasibility of a 24-h mobile reporting system, designed for speeding up malaria notifications, from primary healthcare facilities to district, provincial, and national malaria programmes in South Africa.

METHODS

A prospective descriptive study utilizing primary data collected from structured interviews with healthcare workers in public healthcare facilities was used to compare two reporting systems (24-h mobile reporting system and the paper-based reporting system) in malaria endemic provinces (Limpopo, Mpumalanga and KwaZulu-Natal). Data on completeness of reporting, simplicity, user acceptability and technical limitations were analysed. A Wilcoxon signed-rank test was used to compare the time difference between the two reporting systems.

RESULTS

There were 1819 cases of malaria reported through the paper-based system, and 63.2% (1149) of those cases were also reported through the 24-h mobile reporting system. Out of the 272 healthcare workers who were interviewed, 40% (108) had seen malaria patients and reported a case through the 24-h mobile reporting system. The median time for cases to be reported through the 24-h mobile reporting system was significantly shorter at < 1 day (range < 1 to 31 days) compared to the paper-based system at 3 days (range 2 to > 39 days) (p < 0.001). It was found that 26% (28) were able to use the system and send reports within 2 min, 94% (256) were willing to continue to use the system. Of the 108 healthcare workers who reported a case, 18.5% (20) experienced network challenges.

CONCLUSIONS

The 24-h mobile reporting system is user friendly and trained healthcare workers are willing to use the system, despite network limitations. The 24-h mobile reporting system reduces the time required for diagnosed cases to be notified by the health care facility to district, provincial and national levels. The 24-h mobile reporting system is a feasible option for malaria notification in South Africa and will assist with early detection of malaria outbreaks.

Assessment of individual and household malaria risk factors among women in a South African village

There is need to understand how various malaria risk factors interact at the individual, household and community levels, as well as wider contexts, in order to guide the design and implementation of effective and more comprehensive control strategies. Using a cross-sectional approach, this study investigated various malaria risk factors among residents of Mgedula Village, a malaria-endemic community located in Jozini Local Municipality, UMkhanyakude District, South Africa from May to August 2014. Data from 121 randomly sampled women were collected using close-ended questionnaires. The women were aged between 18 and 40 years; and had been residents in the study area for five years or more. A multivariable logistic regression model was used to measure the association between a history of malaria infection in the previous 12 months and various potential risk factors. The results showed that practicing animal husbandry (OR 20), residing in household structures that had not been sprayed (OR 16.7) and cross-border movement (OR 14.3) were greatly associated with malaria infection. Other factors that were significantly associated with this infection included illiteracy (OR 9.1), having a largely populated household (OR 6.1) and low income (OR 1.65). Individuals with a history of malaria infection were less likely to lack basic malaria-related knowledge (OR 0.58), to have negative attitude towards malaria (OR 0.29) and also to have poor malaria practices (OR 0.3). There was no association between a malaria episode and residing at a long distance from the health facility. Indoor residual spraying indicated a notable reduction of malaria risk at the community level. However, other socio-economic, geographical and socio-demographic factors interacted at different levels to increase this risk among different individuals and households. To achieve malaria elimination by the year 2018, these aspects should be considered when developing and implementing elimination strategies at the individual, household and community levels, among high-risk populations.

Preliminary survey on Anopheles species distribution in Botswana shows the presence of Anopheles gambiae and Anopheles funestus complexes

Background

Botswana is one of the four front line malaria elimination countries in Southern Africa, with malaria control activities that include routine vector control. Past and recent studies have shown that Anopheles arabiensis is the only known vector of Plasmodium parasites in the country. This report presents a preliminary evaluation on Anopheles species composition in seven districts of Botswana with some inferences on their vectorial role.

Results

Overall, 404 Anopheles mosquito females were collected, of which 196 were larvae collected from several breeding sites, and 208 were adults obtained from indoor pyrethrum spray catches (PSC). Anopheles arabiensis (58.9%) accounted for the highest relative frequency in 5 out of 7 districts sampled. The other species collected, among those identified, were barely represented: Anopheles longipalpis type C (16.3%), Anopheles parensis (8.9%), Anopheles quadriannulatus (5.4%), and Anopheles leesoni (0.2%). PCR test for human β-globin on mosquitoes collected by PSC showed that An. arabiensis and An. parensis had bitten human hosts. Moreover, An. arabiensis showed a non-negligible Plasmodium falciparum infection rate in two sites (3.0% and 2.5% in Chobe and Kweneng West districts, respectively).

Conclusions

This work provides first time evidence of Anopheles diversity in several areas of Botswana. Anopheles arabiensis is confirmed to be widespread in all the sampled districts and to be vector of P. falciparum. Moreover, the presence of Anopheles funestus group in Botswana has been assessed. Further research, entomological surveillance activities and possibly vector control programmes need to be better developed and implemented as well as targeting outdoors resting vectors.

Parasites and vectors of malaria on Rusinga Island, Western Kenya

Background

There is a dearth of information on malaria endemicity in the islands of Lake Victoria in western Kenya. In this study malaria prevalence and Plasmodium sporozoite rates on Rusinga Island were investigated. The contribution of different Anopheles species to indoor and outdoor transmission of malaria was also determined.

Methods

Active case detection through microscopy was used to diagnose malaria in a 10% random sample of the human population on Rusinga Island and a longitudinal entomological survey conducted in Gunda village in 2012. Nocturnally active host-seeking mosquitoes were captured indoors and outdoors using odour-baited traps. Anopheles species were tested for the presence of Plasmodium parasites using an enzyme linked immunosorbent assay. All data were analyzed using generalized linear models.

Results

Single infections of Plasmodium falciparum (88.1%), P. malariae (3.96%) and P. ovale (0.79%) as well as multiple infections (7.14%) of these parasites were found on Rusinga Island. The overall malaria prevalence was 10.9%. The risk of contracting malaria was higher among dwellers of Rusinga West than Rusinga East locations (Odds Ratio [OR] = 1.5, 95% Confidence Interval [CI] 1.14 – 1.97, P = 0.003). Parasite positivity was significantly associated with individuals who did not use malaria protective measures (OR = 2.65, 95% CI 1.76 – 3.91, p < 0.001). A total of 1,684 mosquitoes, including 74 anophelines, were captured. Unlike Culex species, more of which were collected indoors than outdoors (P < 0.001), the females of An. gambiae s.l. (P = 0.477), An. funestus s.l. (P = 0.153) and Mansonia species captured indoors versus outdoors were not different. The 46 An. gambiae s.l. collected were mainly An. arabiensis (92.3%). Of the 62 malaria mosquitoes tested, 4, including 2 indoor and 2 outdoor-collected individuals had Plasmodium.

Conclusion

The rather significant and unexpected contribution of P. malariae and P. ovale to the overall malaria prevalence on Rusinga Island underscores the epidemiological importance of these species in the big push towards eliminating malaria. Although current entomological interventions mainly target indoor environments, additional strategies should be considered to prevent outdoor transmission of malaria.