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An. funestus is a major Afrotropical vector of human malaria. This study sought to investigate the larval ecology, sporozoite infection rates and blood meal sources of An. funestus in western Kenya. Larval surveys were carried out in Bungoma (Highland) and Kombewa (lowland) of western Kenya. Aquatic habitats were identified, characterized, georeferenced and carefully examined for mosquito larvae and predators. Indoor resting mosquitoes were sampled using pyrethrum spray catches. Adults and larvae were morphologically and molecularly identified to species. Sporozoite infections and blood meal sources were detected using real-time PCR and ELISA respectively. Of the 151 aquatic habitats assessed, 62/80 (78%) in Bungoma and 58/71(82%) in Kombewa were positive for mosquito larvae. Of the 3,193 larvae sampled, An. funestus larvae constitute 38% (1224/3193). Bungoma recorded a higher number of An. funestus larvae (85%, 95%, CI, 8.722-17.15) than Kombewa (15%, 95%, CI, 1.33-3.91). Molecular identification of larvae showed that 89% (n = 80) were An. funestus. Approximately 59%, 35% and 5% of An. funestus larvae co-existed with An. gambiae s.l, Culex spp and An. coustani in the same habitats respectively. Of 1,221 An. funestus s.l adults sampled, molecular identifications revealed that An. funestus constituted 87% (n = 201) and 88% (n = 179) in Bungoma and Kombewa, respectively. The Plasmodium falciparum sporozoite rate of An. funestus in Bungoma and Kombewa was 2% (3/174) and 1% (2/157), respectively, and the human blood index of An. funestus was 84% (48/57) and 89% (39/44) and for Bungoma and Kombewa, respectively. Man-made ponds had the highest abundance of An. funestus larvae. Multiple regression and principal component analyses identified the distance to the nearest house as the key environmental factor associated with the abundance of An. funestus larvae in aquatic habitats. This study serves as a guide for the control of An. funestus and other mosquito species to complement existing vector control strategies.

Background The widespread use of indoor-based malaria vector control interventions has been shown to alter the behaviour of vectors in Africa. There is an increasing concern that such changes could sustain residual transmission. This study was conducted to assess vector species composition, feeding behaviour and their contribution to indoor and outdoor malaria transmission in western Kenya. Methods Anopheles mosquito collections were carried out from September 2015 to April 2016 in Ahero and Iguhu sites, western Kenya using CDC light traps (indoor and outdoor), pyrethrum spray catches (PSCs) (indoor) and pit shelters (outdoor). Species within Anopheles gambiae s.l. and Anopheles funestus s.l. were identified using polymerase chain reaction (PCR). Enzyme-linked immunosorbent assay (ELISA) was used to determine mosquito blood meal sources and sporozoite infections. Results A total of 10,864 female Anopheles mosquitoes comprising An. gambiae s.l. (71.4%), An. funestus  s.l. (12.3%),  Anopheles coustani (9.2%) and Anopheles pharoensis (7.1%) were collected. The majority (61.8%) of the anopheline mosquitoes were collected outdoors. PCR result (n = 581) revealed that 98.9% An. arabiensis and 1.1% An. gambiae s.s. constituted An. gambiae s.l. in Ahero while this was 87% An. gambiae s.s. and 13% An. arabiensis in Iguhu. Of the 108 An. funestus s.l. analysed by PCR, 98.1% belonged to An. funestus s.s. and 1.9% to Anopheles leesoni . The human blood index (HBI) and bovine blood index (BBI) of An. arabiensis was 2.5 and 73.1%, respectively. Anopheles gambiae s.s. had HBI and BBI of 50 and 28%, respectively. The HBI and BBI of An. funestus was 60 and 22.3%, respectively. Forage ratio estimate revealed that An. arabiensis preferred to feed on cattle, An. gambiae s.s. showed preference for both human and cattle, while An. funestus preferred human over other hosts. In Ahero, the sporozoite rates for An. arabiensis and An. funestus were 0.16 and 1.8%, respectively, whereas in Iguhu, the sporozoite rates for An. gambiae s.s. and An. funestus were 2.3 and 2.4%, respectively. In Ahero, the estimated indoor and outdoor entomological inoculation rate (EIR) was 108.6 infective bites/person/year (79.0 from An. funestus and 29.6 from An. arabiensis ) and 43.5 infective bites/person/year (27.9 from An. arabiensis and 15.6 from An. funestus ), respectively. In Iguhu, the estimated indoor and outdoor EIR was 24.5 infective bites/person/year (18.8 from An. gambiae s.s. and 5.7 from An. funestus ) and 5.5 infective bites/person/year (all from An. gambiae s.s.), respectively. Conclusion Anopheles gambiae s.s. showed an increasing tendency to feed on cattle. Anopheles arabiensis was highly zoophagic, whereas An. funestus showed anthropophagic behaviour. While the majority of malaria transmission occurred indoor, the magnitude of outdoor transmission was considerably high. Additional control tools that complement the existing interventions are required to control residual transmission.

Background Timely molecular surveillance of Plasmodium falciparum kelch 13 ( k13 ) gene mutations is essential for monitoring the emergence and stemming the spread of artemisinin resistance. Widespread artemisinin resistance, as observed in Southeast Asia, would reverse significant gains that have been made against the malaria burden in Africa. The purpose of this study was to assess the prevalence of k13 polymorphisms in western Kenya and Ethiopia at sites representing varying transmission intensities between 2018 and 2022. Methods Dried blood spot samples collected through ongoing passive surveillance and malaria epidemiological studies, respectively, were investigated. The k13 gene was genotyped in P. falciparum isolates with high parasitaemia: 775 isolates from four sites in western Kenya (Homa Bay, Kakamega, Kisii, and Kombewa) and 319 isolates from five sites across Ethiopia (Arjo, Awash, Gambella, Dire Dawa, and Semera). DNA sequence variation and neutrality were analysed within each study site where mutant alleles were detected. Results Sixteen Kelch13 haplotypes were detected in this study. Prevalence of nonsynonymous k13 mutations was low in both western Kenya (25/783, 3.19%) and Ethiopia (5/319, 1.57%) across the study period. Two WHO-validated mutations were detected: A675V in three isolates from Kenya and R622I in four isolates from Ethiopia. Seventeen samples from Kenya carried synonymous mutations (2.17%). No synonymous mutations were detected in Ethiopia. Genetic variation analyses and tests of neutrality further suggest an excess of low frequency polymorphisms in each study site. Fu and Li’s F test statistic in Semera was 0.48 (P > 0.05), suggesting potential population selection of R622I, which appeared at a relatively high frequency (3/22, 13.04%). Conclusions This study presents an updated report on the low frequency of k13 mutations in western Kenya and Ethiopia. The WHO-validated R622I mutation, which has previously only been reported along the north-west border of Ethiopia, appeared in four isolates collected from eastern Ethiopia. The rapid expansion of R622I across Ethiopia signals the need for enhanced monitoring of the spread of drug-resistant P. falciparum parasites in East Africa. Although ACT remains currently efficacious in the study areas, continued surveillance is necessary to detect early indicators of artemisinin partial resistance.

Background Zika virus (ZIKV) is an emerging mosquito-borne arbovirus that can produce serious public health consequences. In 2016, ZIKV caused an epidemic in many countries around the world, including the United States. ZIKV surveillance and vector control is essential to combating future epidemics. However, challenges relating to the timely publication of case reports significantly limit the effectiveness of current surveillance methods. In many countries with poor infrastructure, established systems for case reporting often do not exist. Previous studies investigating the H1N1 pandemic, general influenza and the recent Ebola outbreak have demonstrated that time- and geo-tagged Twitter data, which is immediately available, can be utilized to overcome these limitations. Methods In this study, we employed a recently developed system called Cloudberry to filter a random sample of Twitter data to investigate the feasibility of using such data for ZIKV epidemic tracking on a national and state (Florida) level. Two auto-regressive models were calibrated using weekly ZIKV case counts and zika tweets in order to estimate weekly ZIKV cases 1 week in advance. Results While models tended to over-predict at low case counts and under-predict at extreme high counts, a comparison of predicted versus observed weekly ZIKV case counts following model calibration demonstrated overall reasonable predictive accuracy, with an R 2 of 0.74 for the Florida model and 0.70 for the U.S. model. Time-series analysis of predicted and observed ZIKV cases following internal cross-validation exhibited very similar patterns, demonstrating reasonable model performance. Spatially, the distribution of cumulative ZIKV case counts (local- & travel-related) and zika tweets across all 50 U.S. states showed a high correlation ( r  = 0.73) after adjusting for population. Conclusions This study demonstrates the value of utilizing Twitter data for the purposes of disease surveillance. This is of high value to epidemiologist and public health officials charged with protecting the public during future outbreaks.

Background Ethiopia is one of the African countries where Plasmodium falciparum and P. vivax co-exist. Monitoring and evaluation of current malaria transmission status is an important component of malaria control as it is a measure of the success of ongoing interventions and guides the planning of future control and elimination efforts. Main text We evaluated changes in malaria control policy in Ethiopia, and reviewed dynamics of country-wide confirmed and clinical malaria cases by Plasmodium species and reported deaths for all ages and less than five years from 2001 to 2016. Districts level annual parasite incidence was analysed to characterize the malaria transmission stratification as implemented by the Ministry of Health. We found that Ethiopia has experienced major changes from 2003 to 2005 and subsequent adjustment in malaria diagnosis, treatment and vector control policy. Malaria interventions have been intensified represented by the increased insecticide treated net (ITN) and indoor residual spraying (IRS) coverage, improved health services and improved malaria diagnosis. However, countrywide ITN and IRS coverages were low, with 64% ITN coverage in 2016 and IRS coverage of 92.5% in 2016 and only implemented in epidemic-prone areas of > 2500 m elevation. Clinical malaria incidence rate dropped from an average of 43.1 cases per 1000 population annually between 2001 and 2010 to 29.0 cases per 1000 population annually between 2011 and 2016. Malaria deaths decreased from 2.1 deaths per 100 000 people annually between 2001 and 2010 to 1.1 deaths per 100 000 people annually between 2011 to 2016. There was shrinkage in the malaria transmission map and high transmission is limited mainly to the western international border area. Proportion of P. falciparum malaria remained nearly unchanged from 2000 to 2016 indicating further efforts are needed to suppress transmission. Conclusions Malaria morbidity and mortality have been significantly reduced in Ethiopia since 2001, however, malaria case incidence is still high, and there were major gaps between ITN ownership and compliance in malarious areas. Additional efforts are needed to target the high transmission area of western Ethiopia to sustain the achievements made to date.

Background Malaria continues to represent an important public health problem in Ethiopia. The expansion of irrigated agricultural development projects turns out to be a major impediment to long-lasting and sustainable malaria prevention and control efforts in the country. The aim of this study was to determine the micro-epidemiology of malaria and associated risk factors in and around Gojeb Horizon Irrigation Plantation in southwest Ethiopia. Methods A community-based comparative cross-sectional study was conducted from May to June 2018 in Gimbo District, southwest Ethiopia. A total of 186 households (94 from irrigated village and 92 from non-irrigated village) were randomly selected from among the communities living around the Gojeb Horizon plantation. In total, 718 individuals (368 from irrigated village and 350 from non-irrigated village) were recruited from the selected households. A finger-prick blood sample was obtained from each participant. Socio-demographic data from the households and individual study participants were collected using a semi-structured questionnaire. Multivariate regression was used to assess factors associated with micro-epidemiology of malaria. P-value < 0.05 was considered statistically significant. Results The prevalence of malaria in irrigated and non-irrigated villages was 8.2% and 3.4%, respectively. Plasmodium falciparum , Plasmodium vivax and mixed infections accounted for 57.1%, 38.1%, and 4.8% of the cases, respectively. Individuals living in the irrigated villages were 2.53 (95% CI: 1.23–5.20) times at higher risk of Plasmodium infection as compared to those living in the non-irrigated village. Age (AOR = 1.03, 95% CI: 1.01–1.06) and non-use of long-lasting insecticidal net (AOR = 2.72, 95% CI: 1.03–7.22) were co-predictors of malaria infection in the area. Conclusion This study revealed that communities living in irrigation village were at a higher risk of Plasmodium infection than those living in non-irrigated village, which necessitates the development of tailored interventions that are both targeted and customized.

Background In Ethiopia, the fight against malaria faces significant challenges, including the emergence of insecticide resistance, vector behavioral change, population movement, climate change, civil unrest, emergence of COVID-19 pandemic, unplanned urbanization, invasion and spread of urban malaria vector Anopheles stephensi . Modeling the complex relationship and contribution of these factors to malaria infection is essential for ultimate malaria elimination. Hence, the aim of this study is to model the direct and indirect effect of factors affecting the risk of urban malaria infection in eastern Ethiopia where an invasive malaria vector has been recently detected. Methods A facility based cross-sectional study was conducted among 329 febrile urban resident patients visiting public health facilities of Dire Dawa city using an interviewer administered questionnaire. Structural Equation Modeling (SEM) was done to identify the direct and indirect effects of factors for malaria infection. Lavaan (Latent variable analysis) package was used in R and diagonally weighted least square (DWLS) estimation method was employed. Results The confirmatory factor analysis indicated that all selected factors were significantly loaded on their respective latent variables. The direct effect of the final model indicated that wealth index had a negative statistically significant effect on insecticide treated nets (ITN) utilization (-0.66; p  < 0.001) and knowledge on malaria and its prevention (-0.63; p  < 0.001). Attitude had positive effect on ITN utilization (0.16; p  = 0.049) and having history of travel outside the city had significant positive effect on malaria infection (0.969; p  = 0.01). The indirect effect analysis revealed two pathways in which attitude and utilization as the mediating factor significantly influenced the risk of malaria infection (indirect path coefficient=-0.091; p  = 0.038) and (indirect path coefficient = 0.029; p  = 0.048) respectively. Conclusion SEM is an effective technique that identified the direct and indirect effects of wealth index, ITN utilization, knowledge, attitude and history of travel on risk of urban malaria infection. Hence, strengthening holistic approach and urban-targeted malaria interventions should be enhanced to prevent and control malaria infection in urban settings.

The presence of invasive Anopheles stephensi has been confirmed from field studies in several urban, peri-urban and rural areas of Ethiopia. Recent studies have shown that these mosquitoes are resistant to common public health insecticides, namely pyrethroids (deltamethrin, permethrin, and alpha-cypermethrin), Carbamates (bendiocarb and propoxur), and organophosphates (pirimiphos-methyl). This study aimed to assess the susceptibility of populations of An. stephensi from Ethiopia to novel chemical insecticides recently recommended for vector control, namely, broflanilide (a meta-diamide targeting GABA receptors), clothianidin (a neonicotinoid disrupting nerve signals), and chlorfenapyr (a pyrrole disrupting respiratory pathways ), as well as pyriproxyfen (an insect growth regulator mimicking an insect juvenile hormone which results in adult mosquito emergence inhibition), which is recommended for mosquito larval control. The WHO bottle bioassay test was conducted to assess the susceptibility level of populations of An. stephensi reared from larval collections exposed to recommended diagnostic doses of broflanilide, clothianidin, chlorfenapyr, and pyriproxyfen at 18 µg/bottle, 10 µg/bottle 100 µg/bottle, and 100 µg/bottle, respectively. The solvent used was either a mixture of Mero and acetone or acetone alone. Control bottles were treated with solvent only. Mortality was recorded 24 hours post- exposure for all the insecticides and continued to 72 hours post- exposure for chlorfenapyr and pyriproxyfen. The effect of pyriproxyfen on mosquito fecundity (oviposition) was also assessed over four days after 72 hours holding period.Mortality rates of An. stephensi 24 hrs post-exposure to broflanilide and clothianidin was 100% (100/100), while mortality rates at 24 and 48 hrs post-exposure to chlorfenapyr was 66% (66/100), and 100% (100/100), respectively indicating high susceptibility of populations of An stephensi to the three candidate chemical insecticides. Mortality rates of An. stephensi 24hr , 48hr and 72 hr post-exposure to pyriproxyfen was 0%, 11% (11/100), and 15% (15/100), respectively. There was no mosquito mortality in the controls. Moreover, oviposition inhibition rate in adult female of An. stephensi exposed to pyriproxyfen was 100% while oviposition rate in adult female of An.stephensi in the control was 100%.The study revealed that populations of An. stephensi from Ethiopia were fully susceptible to the three novel chemical insecticides (broflanilide, chlorfenapyr and clothianidin) and an insect growth regulator ( Pyriproxyfen) resulted in complete oviposition inhibition. These findings suggest that the tested candidate chemical insecticides and insect growth regulator (IGR) can be used for indoor residual spraying (IRS) and larviciding, respectively for the control of an invasive malaria vector An. stephensi in Ethiopia.

Background Malaria control in African cities faces challenges mainly due to unplanned urbanization and the spread of Anopheles stephensi . Urbanization is changing malaria dynamics, driven by environmental changes and population growth, with nearly 70% of people projected to live in urban areas by 2050. This scoping review maps the epidemiology of urban malaria in sub-Saharan Africa, identifying research gaps and guiding strategies for control and elimination. Methods A structured search across multiple databases was performed using predefined eligibility criteria to select articles. Accordingly, PubMed, Medline EBSCO, Google scholar, Science direct, Cochrane library and grey literature sources were searched for relevant articles. The Joanna Briggs Institute (JBI) guidelines were followed for evidence selection, data extraction, and presentation of findings. Peer-reviewed and gray literature published in English after 2014 that reported on the prevalence, incidence, or risk factors of urban malaria in sub-Saharan Africa was included in the review. Results Of the 2459 records identified from various databases, 32 articles were selected for review. A majority of those reviewed studies were community-based studies conducted in urban settings of sub-Saharan African countries. This review found the prevalence of malaria between 0.06% and 58%. This heterogeneity in prevalence is due to differences in diagnostic methods, study design, population characteristics, diagnostic methods, and environmental factors. A majority of those reviewed studies reported the prevalence between 10 and 30% with Plasmodium falciparum and Plasmodium vivax the dominant species. The review identified key factors associated with urban malaria infection, including socioeconomic status, travel history, prior infection, proximity to water sources, availability of vegetation in the compound, temperature, humidity, livestock ownership, and ITN utilization. Conclusion This review found a high prevalence of urban malaria infection in sub-Saharan Africa and there was regional variation. Sociodemographic and socioeconomic status, travel history, ITN utilization, previous history of malaria infection and environmental factors like proximity to water sources, presence of vegetation, temperature, humidity, and livestock ownership were identified as factors associated with urban malaria infection. Hence, there is a need for a comprehensive approach to control urban malaria, including environmental management, improved diagnostics and treatment, socio-economic interventions, and better urban planning.

Background Malaria prevention and control strategies have been hampered by urbanization and the spread of Anopheles stephensi . The spread of this vector into Africa further complicates the already complex malaria situation, that could put about 126 million Africans at risk of infection. Hence, this study aimed to assess the determinants of urban malaria, focusing on the role of urbanization and the distribution of An. stephensi in Eastern Ethiopia. Methods A matched case control study was conducted among febrile urban residents of Dire Dawa (malaria positive as cases and negative as a control). A capillary blood sample was collected for parasite identification using microscopic examination and an interviewer administered questionnaire was used to collect additional data. Centers for Disease Control and Prevention miniature light traps (CDC-LT) and Prokopack aspirator were used to collect adult mosquito vectors from the selected cases and control houses to identify the mosquito vector species. Then, the data were exported to STATA for analysis. Conditional logistic regression was done to identify determinants, and principal component Analysis (PCA) was done for some independent variables. Results This study enrolled 132 cases and 264 controls from urban setting only. Of the 132 cases, 90 cases were positive for Plasmodium falciparum , 34 were positive for Plasmodium vivax and 8 had mixed infections. All cases and controls were similar with regard to their respective age and sex. Travel history (AOR: 13.1, 95% CI 2.8–61.4), presence of eves and holes on walls (AOR: 2.84, 95% CI 1.5–5.5), history of malaria diagnosis (AOR: 2.4, 95% CI 1.1–5.3), owning any livestock (AOR: 7.5, 95% CI 2.4–22.8), presence of stagnant water in the area (AOR: 3.2, 95% CI 1.7–6.1), sleeping under bed net the previous night (AOR: 0.21, 95% CI 0.1–0.6) and knowledge on malaria and its prevention (AOR: 2.2, 95% CI 1.2–4.1) were determinants of urban malaria infection. About 34 adult Anopheles mosquitoes were collected and identified from those selected cases and control houses and 27 of them were identified as An. stephensi . Conclusion Among the cases, the dominant species were P. falciparum . This study identified travel history, house condition, past infection, livestock ownership, stagnant water, bed net use, and malaria knowledge as determinants of infection. This study also found the dominance of the presence of An. stephensi among the collected mosquito vectors. This suggests that the spread of An. stephensi may be impacting malaria infection in the study area. Hence, strengthening urban-targeted malaria interventions should be enhanced to prevent and control further urban malaria infection and spread.