An Ensemble Framework for Projecting the Impact of Lymphatic Filariasis Interventions Across Sub-Saharan Africa at a Fine Spatial Scale.

BACKGROUND: Lymphatic filariasis (LF) is a neglected tropical disease targeted for elimination as a public health problem by 2030. Although mass treatments have led to huge reductions in LF prevalence, some countries or regions may find it difficult to achieve elimination by 2030 owing to various factors, including local differences in transmission. Subnational projections of intervention impact are a useful tool in understanding these dynamics, but correctly characterizing their uncertainty is challenging. METHODS: We developed a computationally feasible framework for providing subnational projections for LF across 44 sub-Saharan African countries using ensemble models, guided by historical control data, to allow assessment of the role of subnational heterogeneities in global goal achievement. Projected scenarios include ongoing annual treatment from 2018 to 2030, enhanced coverage, and biannual treatment. RESULTS: Our projections suggest that progress is likely to continue well. However, highly endemic locations currently deploying strategies with the lower World Health Organization recommended coverage (65%) and frequency (annual) are expected to have slow decreases in prevalence. Increasing intervention frequency or coverage can accelerate progress by up to 5 or 6 years, respectively. CONCLUSIONS: While projections based on baseline data have limitations, our methodological advancements provide assessments of potential bottlenecks for the global goals for LF arising from subnational heterogeneities. In particular, areas with high baseline prevalence may face challenges in achieving the 2030 goals, extending the "tail" of interventions. Enhancing intervention frequency and/or coverage will accelerate progress. Our approach facilitates preimplementation assessments of the impact of local interventions and is applicable to other regions and neglected tropical diseases.

Fine-scale heterogeneity in Schistosoma mansoni force of infection measured through antibody response.

Schistosomiasis is among the most common parasitic diseases in the world, with over 142 million people infected in low- and middle-income countries. Measuring population-level transmission is centrally important in guiding schistosomiasis control programs. Traditionally, human Schistosoma mansoni infections have been detected using stool microscopy, which is logistically difficult at program scale and has low sensitivity when people have low infection burdens. We compared serological measures of transmission based on antibody response to S. mansoni soluble egg antigen (SEA) with stool-based measures of infection among 3,663 preschool-age children in an area endemic for S. mansoni in western Kenya. We estimated force of infection among children using the seroconversion rate and examined how it varied geographically and by age. At the community level, serological measures of transmission aligned with stool-based measures of infection (ρ = 0.94), and serological measures provided more resolution for between-community differences at lower levels of infection. Force of infection showed a clear gradient of transmission with distance from Lake Victoria, with 94% of infections and 93% of seropositive children in communities <1.5 km from the lake. Force of infection increased through age 3 y, by which time 65% (95% CI: 53%, 75%) of children were SEA positive in high-transmission communities-2 y before they would be reached by school-based deworming programs. Our results show that serologic surveillance platforms represent an important opportunity to guide and monitor schistosomiasis control programs, and that in high-transmission settings preschool-age children represent a key population missed by school-based deworming programs.

Factors influencing school re-entry among adolescents in Kenya.

BACKGROUND: The number of out-of-school children and adolescents has been increasing globally. In sub-Saharan Africa, an estimated 23 million adolescents leave school due to poverty, teenage pregnancy, and unspecified illnesses. The reasons for absenteeism are well-known but the factors involved in the decision to return to school have not been analyzed. This study aimed to identify the factors that promote primary school re-entry among chronic adolescent absentees in rural sub-Saharan Africa. METHODS: Qualitative data were gathered through participant observation, in-depth interviews, and focus group discussions involving nine pupils who returned to school after chronic absenteeism and 140 adult stakeholders in Mbita sub-county, Kenya. Data were analyzed using thematic analysis. RESULTS: The thematic analysis results showed that four factors promoted school re-entry, namely: (1) social norms: "school for a better life"; (2) linkage of community and school; (3) supportive environment; and (4) using discipline to make adolescents serious about their education. CONCLUSIONS: School re-entry among chronic absentees in Mbita sub-county is promoted by both community and school factors. It was observed that social norms regarded an education as a "passport to a better life." Adolescents, teachers, and community leaders view education as a means of improving one's socio-economic status. Two essential elements of health-promoting schools, a supportive environment and a linkage with community, effectively promoted returning to the school among adolescents. The introduction of health-promoting schools was recommended to implement a school re-entry policy in Kenya effectively.

Has the double burden of malnutrition reached pupils in rural western Kenya?

BACKGROUND: Undernutrition and overnutrition have been considered separate challenges caused by the distinct factors in distinct settings. The double burden of malnutrition is defined as the coexistence of both undernutrition and overnutrition, which has now spread globally, especially in low- and middle-income countries. In Kenya, the double burden of malnutrition is present in the capital city but the situation in rural areas currently remains unknown. The aim of this study was therefore to analyze nutritional status in rural Kenya. METHODS: Data from height and weight measurements conducted by teachers in the third term of school year 2013 were collected from primary schools. Teachers were trained by experts before starting the measurements. The Z-scores of height-for-age, weight-for-age, and body mass index-for-age were calculated using AnthroPlus, and nutritional status was defined according to the World Health Organization guidelines. RESULTS: Data analyzed from 7,447 pupils (3,763 boys and 3,684 girls) showed that 12.4% were stunted and 7.8% were underweight among those ≤120 months old, and 11.7% were thin among those >120 months old. Boys were more likely to be stunted than girls. Boys were more likely to be underweight and girls were more likely to be overweight in the older age group. CONCLUSION: The double burden of malnutrition was not found, and undernutrition was still common among schoolchildren in the study area. However, it is important to monitor nutritional status due to adverse effects of rapid urbanization. Height and weight measurements in schools may be useful for monitoring the nutritional status of schoolchildren.

Effects, equity, and cost of school-based and community-wide treatment strategies for soil-transmitted helminths in Kenya: a cluster-randomised controlled trial.

BACKGROUND: School-based deworming programmes can reduce morbidity attributable to soil-transmitted helminths in children but do not interrupt transmission in the wider community. We assessed the effects of alternative mass treatment strategies on community soil-transmitted helminth infection. METHODS: In this cluster-randomised controlled trial, 120 community units (clusters) serving 150 000 households in Kenya were randomly assigned (1:1:1) to receive albendazole through annual school-based treatment targeting 2-14 year olds or annual or biannual community-wide treatment targeting all ages. The primary outcome was community hookworm prevalence, assessed at 12 and 24 months through repeat cross-sectional surveys. Secondary outcomes were Ascaris lumbricoides and Trichuris trichiura prevalence, infection intensity of each soil-transmitted helminth species, and treatment coverage and costs. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT02397772. FINDINGS: After 24 months, prevalence of hookworm changed from 18·6% (95% CI 13·9-23·2) to 13·8% (10·5-17·0) in the annual school-based treatment group, 17·9% (13·7-22·1) to 8·0% (6·0-10·1) in the annual community-wide treatment group, and 20·6% (15·8-25·5) to 6·2% (4·9-7·5) in the biannual community-wide treatment group. Relative to annual school-based treatment, the risk ratio for annual community-wide treatment was 0·59 (95% CI 0·42-0·83; p<0·001) and for biannual community-wide treatment was 0·46 (0·33-0·63; p<0·001). More modest reductions in risk were observed after 12 months. Risk ratios were similar across demographic and socioeconomic subgroups after 24 months. No adverse events related to albendazole were reported. INTERPRETATION: Community-wide treatment was more effective in reducing hookworm prevalence and intensity than school-based treatment, with little additional benefit of treating every 6 months, and was shown to be remarkably equitable in coverage and effects. FUNDING: Bill & Melinda Gates Foundation, the Joint Global Health Trials Scheme of the Medical Research Council, the UK Department for International Development, the Wellcome Trust, and the Children's Investment Fund Foundation.

Soil-transmitted helminths and schistosomiasis among pre-school age children in a rural setting of Busia County, Western Kenya: a cross-sectional study of prevalence, and associated exposures.

BACKGROUND: Soil-transmitted helminths (STH) and schistosomiasis continue to cause serious health problems among affected communities. To ensure that infection transmission levels are reduced, repeated mass drug administration at regular intervals has been recommended by World Health Organization. Pre-school age children (PSAC) have been neglected both in terms of research activities and in control programmes in the past for reasons that they carry insignificant infection levels. The current study determined risk factors that contribute to differences in infection prevalence among enrolled and non-enrolled PSAC in Busia County, western Kenya. METHODS: This was a comparative cross-sectional study that compared STH and Schistosoma mansoni infections among enrolled and non-enrolled PSAC in Busia County. Simple random sampling was used to select study participants. A total of 327 enrolled and 326 non-enrolled PSAC (n = 653) were recruited from five participating schools, and the neighboring villages. Statistical analysis was performed using STATA version 14 (STATA Corporation, College Station, TX, USA). Differences in proportions were assessed using the z-test statistic for testing sample proportions. Univariable and multivariable logistic regression were used to test the associations between the variables. RESULTS: The prevalence of STH and Schistosoma mansoni infection was 17.0% (95%CI: 13.1-22.1), and 11.8% (95%CI:11.0-12.9) respectively. Specific STH species prevalence were 12.9% (95%CI:7.0-23.5) for Trichuris trichiura, 8.3% (95%CI:8.2-8.3) for Ascaris lumbricoides, and 1.2% (95%CI:1.2-1.2) for hookworms. Prevalence of T. trichiura was higher among enrolled PSAC 16.9% (95%CI: 6.8-41.9); p = 0.003, compared to the non-enrolled 8.9% (95%CI:4.3-18.2). From univariable analysis, lack of improved water source for drinking OR 2.01, (95%CI:1.29-3.13); p = 0.002, and not wearing shoes OR 3.42, (95%CI:1.14-10.29); p = 0.028, were some of the significant factors associated with STH infection. While for multivariable analysis, bathing/swimming in a river daily, aOR 3.99 (95%CI:1.98-8.06); p = 0.001 was a key significant factor for S. mansoni infections. CONCLUSION: There was high prevalence of STH infection among enrolled PSAC despite having participated in the national school-based deworming programme. Hence the need for continued mass drug administration to reduce the intensity of infections among these age group. In addition, further research maybe needed to identify drivers of STH infection particularly T. trichiura among PSAC.

Diversity of Taenia and Hydatigera (Cestoda: Taeniidae) in domestic dogs in Kenya.

Taenia species of domestic dogs can cause cysticercosis and coenurosis in a wide range of intermediate hosts including humans. Most taeniids of dogs are globally distributed, but some wildlife-transmitted species can be specific for certain regions. Generally, little information exists on the species composition and frequency in most regions of the world, which impairs risk assessment and control strategies. This study determined the range of taeniid species in dogs in four widely spaced areas of Kenya by genetic identification of eggs in faeces collected from the environment. Individual taeniid eggs were characterised by nested polymerase chain reaction of NADH dehydrogenase subunit 1 and cytochrome C oxidase 1 genes, restriction fragment length polymorphism and partial sequencing. Overall 79/1621 (4.9%) faecal samples contained eggs of Taenia or Hydatigera (8.0% in Turkana, 4.8% in Isiolo, 3.8% in Maasai Mara and 1.3% in Meru). Taenia hydatigena and T. multiceps were the most frequent, found in 36 and 15 samples, respectively. Other eggs found in the faeces belonged to T. serialis (sensu lato), T. madoquae (the first record in domestic dogs), T. ovis, T. saginata and Hydatigera taeniaeformis. Polymorphism of nad1 sequences revealed 22 and 8 haplotypes of T. hydatigena and T. multiceps, respectively. The results show the involvement of dogs in both domestic and sylvatic transmission cycles. In addition to the species range, this study provides data on the intraspecific diversity of T. hydatigena and T. multiceps in Kenya, which will serve as baseline information for further studies into cysticercosis and coenurosis in livestock and humans in the region.

Implementation of Kenyan comprehensive school health program: improvement and association with students' academic attainment.

There is growing evidence supporting the effectiveness of a comprehensive school health program. However, implementation in developing countries is a challenge. Furthermore, the available information on the association between a comprehensive school health program and students' academic attainment is limited. In Kenya, a project to verify the effects of a comprehensive school health program was carried out in Mbita sub-county, Homa Bay County from September 2012 to August 2017. This study aimed to clarify the improvement of school health during the project years and the association between school health and students' academic attainment. Primary schools in Mbita sub-county were selected as study sites. We assessed 44 schools' scores on a school health checklist developed from the Kenyan Comprehensive School Health Program, the students' mean score on the Kenya Certificate of Primary Education (KCPE), and absenteeism during the project years (2013-16). The mean school health checklist score (n = 44 schools) was 135.6 in 2013, 169.9 in 2014, 158.2 in 2015 and 181.3 in 2016. The difference of the mean score between 2013 and 2016 was significant. In addition, correlation analysis showed a significant association between mean KCPE score in the project years and school health checklist score (Pearson's coefficient was 0.43, p = 0.004). The results of this study suggest improvements of school health by the implementation of the Kenyan Comprehensive School Health Program and students' academic attainment.

Effects of single and integrated water, sanitation, handwashing, and nutrition interventions on child soil-transmitted helminth and Giardia infections: A cluster-randomized controlled trial in rural Kenya.

BACKGROUND: Helminth and protozoan infections affect more than 1 billion children globally. Improving water quality, sanitation, handwashing, and nutrition could be more sustainable control strategies for parasite infections than mass drug administration, while providing other quality of life benefits. METHODS AND FINDINGS: We enrolled geographic clusters of pregnant women in rural western Kenya into a cluster-randomized controlled trial (ClinicalTrials.gov NCT01704105) that tested 6 interventions: water treatment, improved sanitation, handwashing with soap, combined water treatment, sanitation, and handwashing (WSH), improved nutrition, and combined WSH and nutrition (WSHN). We assessed intervention effects on parasite infections by measuring Ascaris lumbricoides, Trichuris trichiura, hookworm, and Giardia duodenalis among children born to the enrolled pregnant women (index children) and their older siblings. After 2 years of intervention exposure, we collected stool specimens from 9,077 total children aged 2 to 15 years in 622 clusters, including 2,346 children in an active control group (received household visits but no interventions), 1,117 in the water treatment arm, 1,160 in the sanitation arm, 1,141 in the handwashing arm, 1,064 in the WSH arm, 1,072 in the nutrition arm, and 1,177 in the WSHN arm. In the control group, 23% of children were infected with A. lumbricoides, 1% with T. trichiura, 2% with hookworm, and 39% with G. duodenalis. The analysis included 4,928 index children (median age in years: 2) and 4,149 older siblings (median age in years: 5); study households had an average of 5 people, <10% had electricity access, and >90% had dirt floors. Compared to the control group, Ascaris infection prevalence was lower in the water treatment arm (prevalence ratio [PR]: 0.82 [95% CI 0.67, 1.00], p = 0.056), the WSH arm (PR: 0.78 [95% CI 0.63, 0.96], p = 0.021), and the WSHN arm (PR: 0.78 [95% CI 0.64, 0.96], p = 0.017). We did not observe differences in Ascaris infection prevalence between the control group and the arms with the individual interventions sanitation (PR: 0.89 [95% CI 0.73, 1.08], p = 0.228), handwashing (PR: 0.89 [95% CI 0.73, 1.09], p = 0.277), or nutrition (PR: 86 [95% CI 0.71, 1.05], p = 0.148). Integrating nutrition with WSH did not provide additional benefit. Trichuris and hookworm were rarely detected, resulting in imprecise effect estimates. No intervention reduced Giardia. Reanalysis of stool samples by quantitative polymerase chain reaction confirmed the reductions in Ascaris infections measured by microscopy in the WSH and WSHN groups. Trial limitations included imperfect uptake of targeted intervention behaviors, limited power to detect effects on rare parasite infections, and that it was not feasible to blind participants and sample collectors to treatment status. However, lab technicians and data analysts were blinded to treatment status. The trial was funded by the Bill & Melinda Gates Foundation and the United States Agency for International Development. CONCLUSIONS: Integration of improved water quality, sanitation, and handwashing could contribute to sustainable control strategies for Ascaris infections, particularly in similar settings with recent or ongoing deworming programs. Combining nutrition with WSH did not provide further benefits, and water treatment alone was similarly effective to integrated WSH. Our findings provide new evidence that drinking water should be given increased attention as a transmission pathway for Ascaris. TRIAL REGISTRATION: ClinicalTrials.gov NCT01704105.

Sickle Cell and α+-Thalassemia Traits Influence the Association between Ferritin and Hepcidin in Rural Kenyan Children Aged 14-26 Months.

Background: The relation between subclinical hemoglobinopathies and concentrations of the iron-regulatory hormone hepcidin is not well characterized. Objective: We investigated the relation of hepcidin concentration with hemoglobinopathies among young children in Kenya. Methods: We quantified serum hepcidin and ferritin in 435 Kenyan children aged 14-20 mo in a subsample of the Water, Sanitation, and Handwashing (WASH) Benefits Trial. Blood samples were genotyped for α+-thalassemia and for sickle cell disorder. Hepcidin was compared across sickle cell and α+-thalassemia genotypes separately by using generalized linear models, and children who were normozygous for both conditions were also compared with those who had either of these conditions. In the association between hepcidin and ferritin, we assessed effect modification by genotype. Results: In this population, we found that 16.2% had sickle cell trait and 0.2% had sickle cell disorder, whereas 40.0% were heterozygous for α+-thalassemia and 8.2% were homozygous. Hepcidin concentration did not differ by genotype, but effect modification was found by genotype in the association between hepcidin and ferritin (P < 0.1). Among normozygous sickle cell children (HbAA), there was an association between hepcidin and ferritin (ß = 0.92; 95% CI: 0.72, 1.10). However, among those with sickle cell trait (HbAS), the association was no longer significant (ß = 0.31; 95% CI: -0.04, 0.66). Similarly, among children who were normozygous (αα/αα) or heterozygous (-α/αα) for α+-thalassemia, hepcidin and ferritin were significantly associated [ß = 0.94 (95% CI: 0.68, 1.20) and ß = 0.77 (95% CI: 0.51, 1.03), respectively]; however, in children who were homozygous for α+-thalassemia (-α/-α), there was no longer a significant association (ß = 0.45; 95% CI: -0.10, 1.00). Conclusion: Hepcidin was not associated with hemoglobin genotype, but there may be a difference in the way hepcidin responds to iron status among those with either sickle cell trait or homozygous α+-thalassemia in young Kenyan children. This trial was registered at clinicaltrials.gov as NCT01704105.

Comparing the performance of circulating cathodic antigen and Kato-Katz techniques in evaluating Schistosoma mansoni infection in areas with low prevalence in selected counties of Kenya: a cross-sectional study.

BACKGROUND: Kato-Katz technique has been the mainstay test in Schistosoma mansoni diagnosis in endemic areas. However, recent studies have documented its poor sensitivity in evaluating Schistosoma mansoni infection especially in areas with lower rates of transmission. It's the primary diagnostic tool in monitoring impact of the Kenya national school based deworming program on infection transmission, but there is need to consider a more sensitive technique as the prevalence reduces. Therefore, this study explored the relationship between results of the stool-based Kato-Katz technique with urine-based point-of-care circulating cathodic antigen (POC-CCA) test in view to inform decision-making by the program in changing from Kato-Katz to POC-CCA test. METHODS: We used two cross-sectional surveys conducted pre- and post- mass drug administration (MDA) using praziquantel in a representative random sample of children from 18 schools across 11 counties. A total of 1944 children were randomly sampled for the study. Stool and urine samples were tested for S. mansoni infection using Kato-Katz and POC-CCA methods, respectively. S. mansoni prevalence using each technique was calculated and 95% confidence intervals obtained using binomial regression model. Specificity (Sp) and sensitivity (Sn) were determined using 2 × 2 contingency tables and compared using the McNemar's chi-square test. RESULTS: A total of 1899 and 1878 children were surveyed at pre- and post-treatment respectively. S. mansoni infection prevalence was 26.5 and 21.4% during pre- and post-treatment respectively using POC-CCA test, and 4.9 and 1.5% for pre- and post-treatment respectively using Kato-Katz technique. Taking POC-CCA as the gold standard, Kato-Katz was found to have significantly lower sensitivity both at pre- and post-treatment, Sn = 12.5% and Sn = 5.2% respectively, McNemar test χ2m = 782.0, p < 0.001. In overall, the results showed a slight/poor agreement between the two methods, kappa index (k) = 0.11, p < 0.001, inter-rater agreement = 77.1%. CONCLUSIONS: Results showed POC-CCA technique as an effective, sensitive and accurate screening tool for Schistosoma mansoni infection in areas of low prevalence. It was up to 14-fold accurate than Kato-Katz which had extremely inadequate sensitivity. We recommend usage of POC-CCA alongside Kato-Katz examinations by Schistosomiasis control programs in low prevalence areas.

Comparing insecticide-treated bed net use to Plasmodium falciparum infection among schoolchildren living near Lake Victoria, Kenya.

BACKGROUND: Under trial conditions insecticide-treated nets have been shown to provide significant clinical and mortality protection under a range of malaria transmission intensity conditions. There are, however, few operational impact data, notably in very intense transmission conditions. This study, reports on malaria infection among Kenyan schoolchildren living in areas of intense malaria transmission and their reported use of insecticide-treated bed nets. METHODS: 5188 children in 54 schools were randomly sampled from seven counties surrounding Lake Victoria between May and June 2014. A questionnaire was administered to schoolchildren in classes 2-6 on the use of a long-lasting, insecticide-treated net (LLIN) the night before the survey and provided a single blood sample for a rapid diagnostic test for malaria infection. Analysis of the impact of insecticide-treated net use on malaria prevalence was undertaken using a multivariable, mixed effects, logistic regression at 95% confidence interval (CI), taking into account hierarchical nature of the data and results adjusted for school clusters. RESULTS: The overall prevalence of malaria infection was 48.7%, two-thirds (67.9%) of the children reported using LLIN, 91.3% of the children reported that their households own at least one LLIN and the household LLIN coverage was 2.5 persons per one LLIN. The prevalence of infection showed variation across the counties, with prevalence being highest in Busia (66.9%) and Homabay (51.8%) counties, and lowest in Migori County (29.6%). Generally, malaria parasite prevalence differed between age groups and gender with the highest prevalence occurring in children below 7 years (50.6%) and males (52.2%). Adjusting for county and school, there was a significant reduction in odds of malaria infection among the schoolchildren who reported LLIN use the previous night by 14 % (aOR 0.86, 95% CI 0.74-0.98, P < 0.027). CONCLUSION: Malaria transmission continues to be high around Lake Victoria. Despite evidence of increasing pyrethroid resistance and the likely overall efficacy of LLIN distributed several years prior to the survey, LLIN continue to provide protection against infection among school-aged children.

Sleeping on the floor decreases insecticide treated bed net use and increases risk of malaria in children under 5 years of age in Mbita District, Kenya.

Children who sleep on the floor are less likely to use long-lasting insecticidal nets (LLINs); however, the relationship between sleeping location and Plasmodium falciparum infection has not been investigated sufficiently. This study revealed whether sleeping location (bed vs floor) is associated with P. falciparum infection among children 7-59 months old. More than 60% of children slept on the floor. Younger children were significantly more likely to sleep in beds [odds ratio, OR 2.31 (95% confidence interval (CI) 2.02-2.67)]. Nearly 70% of children slept under LLINs the previous night. LLIN use among children who slept on the floor was significantly less than ones sleeping in beds [OR 0.49 (95% CI 0.35-0.68)]. The polymerase chain reaction (PCR) based P. falciparum infection rate and slide based infection rate were 65.2 and 29.7%, respectively. Both infections were significantly higher among children slept on the floor [OR1.51 (95% CI 1.08-2.10) for PCR base, OR 1.62 (95% CI 1.14-2.30) for slide base] while net availability was not significant. Sleeping location was also significant for slide based infection with fever (⩾ 37.5 °C) [2.03 (95% CI 1.14-3.84)] and high parasitemia cases (parasite ⩾ 2500 µL(-1)) [2.07 (95% CI 1.03-4.50)]. The results suggest that sleeping location has a direct bearing on the effectiveness of LLINs.

Current status of Schistosoma mansoni and the factors associated with infection two years following mass drug administration programme among primary school children in Mwea irrigation scheme: A cross-sectional study.

BACKGROUND: Schistosomiasis is a major public health problem in Kenya as well as in many other tropical countries and is considered one of the most prevalent diseases in the rural population. Between 2004 and 2009, primary school children in Mwea irrigation scheme were treated for Schistosoma mansoni. In the four year control programme, there was occurrence of light re-infection with S. mansoni. Therefore, the aim of this study was to assess the current prevalence of S. mansoni, infection two years after the withdrawal of mass drug administration (MDA) programme. METHODS: We carried out a cross-sectional study on a population of 387 children attending 3 primary schools located in Mwea irrigation scheme. Children, aged 8-16 years were interviewed and screened for S. mansoni using duplicate Kato-Katz thick smears. Comparisons of prevalence by age group and gender were tested for significance on the basis of the Wald test. Best prediction factors for infection with S. mansoni were selected using forward - stepwise variable selection method. RESULTS: The overall prevalence of S. mansoni was 53.7 %, (95%CI: 49.0-59.0, p-value = 0.000). Male children had higher prevalence of infection, 66.1 % (95%CI: 59.8-73.2, p-value = 0.000) compared to females. The gender (sex) of a child was the only factor reported to be significantly associated with S. mansoni infection, (OR = 1.9, p-value = 0.015, 95%CI: 1.13-3.21). CONCLUSIONS: There was high prevalence of S. mansoni infections in the study area, two years after the withdrawal of MDA programme. We suggest that treatment should be continued in the school children at regular intervals, monitoring and surveillance intensified to ensure interruption of transmission areas.

Insecticide-treated net use before and after mass distribution in a fishing community along Lake Victoria, Kenya: successes and unavoidable pitfalls.

BACKGROUND: Insecticide-treated nets (ITNs) have proven instrumental in the successful reduction of malaria incidence in holoendemic regions during the past decade. As distribution of ITNs throughout sub-Saharan Africa (SSA) is being scaled up, maintaining maximal levels of coverage will be necessary to sustain current gains. The effectiveness of mass distribution of ITNs, requires careful analysis of successes and failures if impacts are to be sustained over the long term. METHODS: Mass distribution of ITNs to a rural Kenyan community along Lake Victoria was performed in early 2011. Surveyors collected data on ITN use both before and one year following this distribution. At both times, household representatives were asked to provide a complete accounting of ITNs within the dwelling, the location of each net, and the ages and genders of each person who slept under that net the previous night. Other data on household material possessions, education levels and occupations were recorded. Information on malaria preventative factors such as ceiling nets and indoor residual spraying was noted. Basic information on malaria knowledge and health-seeking behaviours was also collected. Patterns of ITN use before and one year following net distribution were compared using spatial and multi-variable statistical methods. Associations of ITN use with various individual, household, demographic and malaria related factors were tested using logistic regression. RESULTS: After infancy (<1 year), ITN use sharply declined until the late teenage years then began to rise again, plateauing at 30 years of age. Males were less likely to use ITNs than females. Prior to distribution, socio-economic factors such as parental education and occupation were associated with ITN use. Following distribution, ITN use was similar across social groups. Household factors such as availability of nets and sleeping arrangements still reduced consistent net use, however. CONCLUSIONS: Comprehensive, direct-to-household, mass distribution of ITNs was effective in rapidly scaling up coverage, with use being maintained at a high level at least one year following the intervention. Free distribution of ITNs through direct-to-household distribution method can eliminate important constraints in determining consistent ITN use, thus enhancing the sustainability of effective intervention campaigns.

Bacterial strain sharing between humans, animals, and the environment among urban households.

Identifying bacterial transmission pathways is crucial to inform strategies aimed at curbing the spread of pathogenic and antibiotic-resistant bacteria, especially in rapidly urbanizing low- and middle-income countries. In this study, we assessed bacterial strain-sharing and dissemination of antibiotic resistance across humans, domesticated poultry, canines, household soil, and drinking water in urban informal settlements in Nairobi, Kenya. We collected 321 samples from 50 households and performed Pooling Isolated Colonies-seq (PIC-seq) by sequencing pools of up to five Escherichia coli colonies per sample to capture strain diversity, strain-sharing patterns, and overlap of antibiotic-resistant genes (ARGs). Bacterial strains isolated from the household environment carried clinically relevant ARGs, reinforcing the role of the environment in antibiotic resistance dissemination. Strain-sharing rates and resistome similarities across sample types were strongly correlated within households, suggesting clonal spread of bacteria is a main driver of dissemination of ARGs in the domestic urban environment. Within households, E. coli strain-sharing was rare between humans and animals but more frequent between humans and drinking water. E. coli contamination in stored drinking water was also associated with higher strain-sharing between humans in the same household. Our study demonstrates that contaminated drinking water facilitates human to human strain sharing and water treatment can disrupt transmission.

Context-Seq: CRISPR-Cas9 Targeted Nanopore Sequencing for Transmission Dynamics of Antimicrobial Resistance.

Antimicrobial resistance (AMR) aligns with a One Health framework in that resistant bacteria and antibiotic resistance genes (ARGs) can be transmitted between humans, animals, and the environment. However, there is a critical need to more precisely understand how and to what extent AMR is exchanged between animals and humans. Metagenomic sequencing has low detection for rare targets such as ARGs, while whole genome sequencing of isolates is burdensome and misses exchange between uncultured bacterial species. We developed a novel, targeted sequencing assay using CRISPR-Cas9 to selectively sequence ARGs and their genomic context with long-read sequencing. Using this method, termed Context-Seq, we investigated overlapping AMR elements containing the ARGs bla CTX-M and bla TEM between adults, children, poultry, and dogs in animal-owning households in Nairobi, Kenya. We identified 22 genetically distinct clusters (> 80%ID over ≥ 3000 bp) containing bla TEM and one cluster containing bla CTX-M that were shared within and between households. Half of the clusters were shared between humans and animals, while the other half were shared only between animals (poultry-poultry, dog-dog, and dog-poultry). We identified potentially pathogenic hosts of ARGs including Escherichia coli, Klebsiella pneumonia, and Haemophilus influenzae across sample types. Context-Seq complements conventional methods to obtain an additional view of bacterial and mammalian hosts in the proliferation of AMR.

Evaluation of a modified quantitative polymerase chain reaction assay for genus Schistosoma detection using stool and urine samples from schistosomiasis endemic areas in Kenya.

INTRODUCTION: The microscopy-based Kato-Katz and urine filtration techniques have traditionally faced challenges in the detection of schistosomiasis in areas with low infection levels. A modified singleplex Schistosoma genus-specific quantitative real-time polymerase chain reaction (qPCR) assay was therefore evaluated as a sensitive and confirmatory schistosomiasis diagnostic test. METHODOLOGY: The qPCR assay utilized primers and probe targeting internal transcribed spacer- 2 (ITS2) sequence of S. mansoni, S. haematobium and S. intercalatum. A plasmid (pDMD801, 100pg/ul) was used as an internal amplification control and its qPCR assays were run in parallel to the Schistosoma assays. This assay utilized samples collected from 774 participants and microscopically examined for three consecutive days. A total of 699 day-one samples (urine and stools) from two schistosomiasis endemic sites were analyzed. Similarly, 75 persons from a non-endemic control site provided both urine and stool samples that were also analyzed. RESULTS: Using microscopy, the proportion of positives in the two endemic regions altogether was 289/699 (41.3%). Using qPCR, 50.4% of the samples (352/699) were found to be positive for schistosome infection. The percentage of positive samples was slightly higher at 57.8% (203/351) in the S. mansoni endemic site compared with the S. haematobium site at 42.8% (149/348). Majority of the microscopy results were light infections at 26.8% (n = 94) and 26.1% (n = 91) while qPCR majority of the infections were high at 41.6% (n = 146) and 31.3% (n = 109) for the S. mansoni and S. haematobium sites, respectively. There were no positives detected by either microscopy or qPCR in the non-endemic site. Using Bayesian Latent Class Model, which does not use any technique as a gold standard, qPCR showed higher sensitivity (86.4% (PCI: 82.1-90.3)) compared to microscopy (75.6% (PCI: 71.1-80.0)). CONCLUSIONS: This study documents a single day-one sample modified Schistosoma qPCR assay as a powerful improved molecular assay for the detection of schistosomiasis infection that utilize either stool or urine samples. The assay is therefore recommended for monitoring in areas with low infection levels to enable accurate determination of the disease's control endpoint.

Association between diet quality and risk of stunting among school-aged children in Schistosoma mansoni endemic area of western Kenya: a cross-sectional study.

BACKGROUND: Healthy eating habits are essential for improving nutritional status and strengthening immunity against infectious diseases. This study examined the relationship between diet quality and stunting in school-aged children in an infectious disease-endemic area of western Kenya. METHODS: This cross-sectional study included 260 school-aged children (age 9-17 years) enrolled in primary schools in Mbita Sub-county, western Kenya. The nutritional status was assessed using anthropometric measurements. Dietary intake was measured using food frequency questionnaires and evaluated using the Food Pyramid (FP) score, which indicates adherence to the Kenyan food-based dietary guideline. Information on the children's age, sex, maternal education, and household wealth index was collected using a household-based questionnaire. Infections with the predominant parasites, such as Schistosoma (S.) mansoni, were detected via microscopy. The trend associations of the FP score with food group intake were examined to characterize the dietary intake of this population. Logistic regression analysis was performed to investigate the relationship between stunting and FP score tertiles, adjusted for sociodemographic and economic indicators and parasitic infection status. RESULTS: Among the studied schoolchildren, 15.0% exhibited stunting, while 76.2% were infected with S. mansoni. The mean FP score was 25.6 out of 50 points. A higher FP score was characterized by a high intake of roots and tubers, dairy products, pulses, and fruits and a low intake of cereals and animal-source foods. The analysis revealed a trend: a lower risk of stunting was evident in groups with elevated FP scores (p for trend = 0.065). However, these trend associations were observable among subjects with either negative or light S. mansoni infection (p for trend = 0.016). CONCLUSIONS: A higher quality diet, as evaluated by FP scores, was associated with a low risk of stunting among school-aged children. Notably, this association seemed to weaken in the presence of a high burden of S. mansoni infection. It highlights the importance of enhancing dietary quality through the promotion of diverse nutrient-dense foods alongside effective S. mansoni infection control for improved growth. This study contributes fundamental knowledge for understanding the diet-malnutrition relationship in areas endemic for S. mansoni infection.

Methodological assessment for efficient collection of Schistosoma mansoni environmental DNA and improved schistosomiasis surveillance in tropical wetlands.

Schistosomiasis, caused by trematodes of genus Schistosoma, is among the most seriously neglected tropical diseases. Although rapid surveillance of risk areas for Schistosoma transmission is vital to control schistosomiasis, the habitat and infection status of this parasite are difficult to assess. Environmental DNA (eDNA) analysis, involving the detection of extra-organismal DNA in water samples, facilitates cost-efficient and sensitive biomonitoring of aquatic environments and is a promising tool to identify Schistosoma habitat and infection risk areas. However, in tropical wetlands, highly turbid water causes filter clogging, thereby decreasing the filtration volume and increasing the risk of false negatives. Therefore, in this study, we aimed to conduct laboratory experiments and field surveys in Lake Victoria, Mbita, to determine the appropriate filter pore size for S. mansoni eDNA collection in terms of particle size and filtration volume. In the laboratory experiment, aquarium water was sequentially filtered using different pore size filters. Targeting >3 µm size fraction was found to be sufficient to capture S. mansoni eDNA particles, regardless of their life cycle stage (egg, miracidia, and cercaria). In the field surveys, GF/D (2.7 µm nominal pore size) filter yielded 2.5-times the filtration volume obtained with a smaller pore size filter and pre-filtration methods under the same time constraints. Moreover, a site-occupancy model was applied to the field detection results to estimate S. mansoni eDNA occurrence and detection probabilities and assess the number of water samples and PCR replicates necessary for efficient eDNA detection. Overall, this study reveals an effective method for S. mansoni eDNA detection in turbid water, facilitating the rapid and sensitive monitoring of its distribution and cost-effective identification of schistosomiasis transmission risk areas.