Combining school-catchment area models with geostatistical models for analysing school survey data from low-resource settings: Inferential benefits and limitations.

School-based sampling has been used to inform targeted responses for malaria and neglected tropical diseases. Standard geostatistical methods for mapping disease prevalence use the school location to model spatial correlation, which is questionable since exposure to the disease is more likely to occur in the residential location. In this paper, we propose to overcome the limitations of standard geostatistical methods by introducing a modelling framework that accounts for the uncertainty in the location of the residence of the students. By using cost distance and cost allocation models to define spatial accessibility and in absence of any information on the travel mode of students to school, we consider three school catchment area models that assume walking only, walking and bicycling and, walking and motorized transport. We illustrate the use of this approach using two case studies of malaria in Kenya and compare it with the standard approach that uses the school locations to build geostatistical models. We argue that the proposed modelling framework presents several inferential benefits, such as the ability to combine data from multiple surveys some of which may also record the residence location, and to deal with ecological bias when estimating the effects of malaria risk factors. However, our results show that invalid assumptions on the modes of travel to school can worsen the predictive performance of geostatistical models. Future research in this area should focus on collecting information on the modes of transportation to school which can then be used to better parametrize the catchment area models.

Annual Primary Care 2030 Convening: Creating an Enabling Ecosystem for Person-Centered Primary Healthcare Models to Achieve Universal Health Coverage in Low- and Middle-Income Countries.

Background: The 2019 United Nations General Assembly High-Level Meeting on Universal Health Coverage and the 2018 Declaration of Astana reaffirm the highest level of political commitment by United Nations Member States to achieve access to health services and primary healthcare for all. Both documents emphasize the importance of person-centered care in both healthcare services and systems design. However, there is limited consensus on how to build a strong primary healthcare system to achieve these goals. Methods: We convened a diverse group of global stakeholders for a high-level dialogue on how to create a person-centered primary healthcare system, using the country examples of the Republic of Kenya and the Socialist Republic of Vietnam. We focused our discussion on four themes to enable the creation of person-centered primary healthcare systems in Kenya and Vietnam: (1) strengthened community, person and patient engagement in subnational and national decision making; (2) improved service delivery; (3) impactful use of innovation and technology; and (4) meaningful and timely use of measurement and data. Findings: Here, we present a summary of our convening's proceedings, with specific insights on how to enable a person-centered primary healthcare system within each of these four domains. Conclusions: Following the 2019 United Nations General Assembly High-Level Meeting on Universal Health Coverage and the 2018 Declaration of Astana, there is high-level commitment and global consensus that a person-centered approach is necessary to achieve high-quality primary healthcare and universal health coverage. We offer our recommendations to the global community to catalyze further discourse and inform policy-making and program development on the path to Universal Health Coverage by 2030.

Anaemia among Kenyan children: a call for improved monitoring and intervention in school-aged children.

BACKGROUND: Anaemia has long been recognised as a major public health problem among young children in lower- and middle-income countries and is an indicator of both poor nutrition and health status. There has been little progress towards improvement of anaemia in part due to its complex aetiology. An added impediment to the progress is that the monitoring of anaemia does not routinely target the whole population, with school-aged children (SAC) largely overlooked. METHODS: We re-examined data on the prevalence of anaemia among children aged <15 y sampled from 2008-2015 in Kenya. RESULTS: Approximately one in four Kenyan children aged <15 y were described as anaemic, including 12% with WHO-defined moderate anaemia and 1% who were severely anaemic. Average haemoglobin concentrations increased with age and the risk of having anaemia decreased with age. However, one in five SAC in Kenya were suffering from anaemia; most were either mild (11.4%) or moderately (10.9%) anaemic. CONCLUSIONS: The monitoring of anaemia in SAC continues to be a neglected area limiting a careful articulation of the need to target interventions in this age group.

Geographic-genetic analysis of Plasmodium falciparum parasite populations from surveys of primary school children in Western Kenya.

Background. Malaria control, and finally malaria elimination, requires the identification and targeting of residual foci or hotspots of transmission. However, the level of parasite mixing within and between geographical locations is likely to impact the effectiveness and durability of control interventions and thus should be taken into consideration when developing control programs. Methods. In order to determine the geographic-genetic patterns of Plasmodium falciparum parasite populations at a sub-national level in Kenya, we used the Sequenom platform to genotype 111 genome-wide distributed single nucleotide polymorphic (SNP) positions in 2486 isolates collected from children in 95 primary schools in western Kenya. We analysed these parasite genotypes for genetic structure using principal component analysis and assessed local and global clustering using statistical measures of spatial autocorrelation. We further examined the region for spatial barriers to parasite movement as well as directionality in the patterns of parasite movement. Results. We found no evidence of population structure and little evidence of spatial autocorrelation of parasite genotypes (correlation coefficients <0.03 among parasite pairs in distance classes of 1km, 2km and 5km; p value<0.01). An analysis of the geographical distribution of allele frequencies showed weak evidence of variation in distribution of alleles, with clusters representing a higher than expected number of samples with the major allele being identified for 5 SNPs. Furthermore, we found no evidence of the existence of spatial barriers to parasite movement within the region, but observed directional movement of parasites among schools in two separate sections of the region studied. Conclusions. Our findings illustrate a pattern of high parasite mixing within the study region. If this mixing is due to rapid gene flow, then "one-off" targeted interventions may not be currently effective at the sub-national scale in Western Kenya, due to the high parasite movement that is likely to lead to re-introduction of infection from surrounding regions. However repeated targeted interventions may reduce transmission in the surrounding regions.

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.

Changing Malaria Prevalence on the Kenyan Coast since 1974: Climate, Drugs and Vector Control.

BACKGROUND: Progress toward reducing the malaria burden in Africa has been measured, or modeled, using datasets with relatively short time-windows. These restricted temporal analyses may miss the wider context of longer-term cycles of malaria risk and hence may lead to incorrect inferences regarding the impact of intervention. METHODS: 1147 age-corrected Plasmodium falciparum parasite prevalence (PfPR2-10) surveys among rural communities along the Kenyan coast were assembled from 1974 to 2014. A Bayesian conditional autoregressive generalized linear mixed model was used to interpolate to 279 small areas for each of the 41 years since 1974. Best-fit polynomial splined curves of changing PfPR2-10 were compared to a sequence of plausible explanatory variables related to rainfall, drug resistance and insecticide-treated bed net (ITN) use. RESULTS: P. falciparum parasite prevalence initially rose from 1974 to 1987, dipped in 1991-92 but remained high until 1998. From 1998 onwards prevalence began to decline until 2011, then began to rise through to 2014. This major decline occurred before ITNs were widely distributed and variation in rainfall coincided with some, but not all, short-term transmission cycles. Emerging resistance to chloroquine and introduction of sulfadoxine/pyrimethamine provided plausible explanations for the rise and fall of malaria transmission along the Kenyan coast. CONCLUSIONS: Progress towards elimination might not be as predictable as we would like, where natural and extrinsic cycles of transmission confound evaluations of the effect of interventions. Deciding where a country lies on an elimination pathway requires careful empiric observation of the long-term epidemiology of malaria transmission.

Malaria in school-age children in Africa: an increasingly important challenge.

School-age children have attracted relatively little attention as a group in need of special measures to protect them against malaria. However, increasing success in lowering the level of malaria transmission in many previously highly endemic areas will result in children acquiring immunity to malaria later in life than has been the case in the past. Thus, it can be anticipated that in the coming years there will be an increase in the incidence of both uncomplicated and severe malaria in school-age children in many previously highly endemic areas. In this review, which focuses primarily on Africa, recent data on the prevalence of malaria parasitaemia and on the incidence of clinical malaria in African school-age children are presented and evidence that malaria adversely effects school performance is reviewed. Long-lasting insecticide treated bednets (LLIN) are an effective method of malaria control but several studies have shown that school-age children use LLINs less frequently than other population groups. Antimalarial drugs are being used in different ways to control malaria in school-age children including screening and treatment and intermittent preventive treatment. Some studies of chemoprevention in school-age children have shown reductions in anaemia and improved school performance but this has not been the case in all trials and more research is needed to identify the situations in which chemoprevention is likely to be most effective and, in these situations, which type of intervention should be used. In the longer term, malaria vaccines may have an important role in protecting this important section of the community from malaria. Regardless of the control approach selected, it is important this is incorporated into the overall programme of measures being undertaken to enhance the health of African school-age children.

Reliability of school surveys in estimating geographic variation in malaria transmission in the western Kenyan highlands.

BACKGROUND: School surveys provide an operational approach to assess malaria transmission through parasite prevalence. There is limited evidence on the comparability of prevalence estimates obtained from school and community surveys carried out at the same locality. METHODS: Concurrent school and community cross-sectional surveys were conducted in 46 school/community clusters in the western Kenyan highlands and households of school children were geolocated. Malaria was assessed by rapid diagnostic test (RDT) and combined seroprevalence of antibodies to bloodstage Plasmodium falciparum antigens. RESULTS: RDT prevalence in school and community populations was 25.7% (95% CI: 24.4-26.8) and 15.5% (95% CI: 14.4-16.7), respectively. Seroprevalence in the school and community populations was 51.9% (95% CI: 50.5-53.3) and 51.5% (95% CI: 49.5-52.9), respectively. RDT prevalence in schools could differentiate between low (<7%, 95% CI: 0-19%) and high (>39%, 95% CI: 25-49%) transmission areas in the community and, after a simple adjustment, were concordant with the community estimates. CONCLUSIONS: Estimates of malaria prevalence from school surveys were consistently higher than those from community surveys and were strongly correlated. School-based estimates can be used as a reliable indicator of malaria transmission intensity in the wider community and may provide a basis for identifying priority areas for malaria control.

Use of rapid diagnostic tests in malaria school surveys in Kenya: does their under-performance matter for planning malaria control?

Malaria rapid diagnostic tests (RDTs) are known to yield false-positive results, and their use in epidemiologic surveys will overestimate infection prevalence and potentially hinder efficient targeting of interventions. To examine the consequences of using RDTs in school surveys, we compared three RDT brands used during a nationwide school survey in Kenya with expert microscopy and investigated the cost implications of using alternative diagnostic approaches in identifying localities with differing levels of infection. Overall, RDT sensitivity was 96.1% and specificity was 70.8%. In terms of classifying districts and schools according to prevalence categories, RDTs were most reliable for the < 1% and > 40% categories and least reliable in the 1-4.9% category. In low-prevalence settings, microscopy was the most expensive approach, and RDT results corrected by either microscopy or polymerase chain reaction were the cheapest. Use of polymerase chain reaction-corrected RDT results is recommended in school malaria surveys, especially in settings with low-to-moderate malaria transmission.

Plasmodium infection, anaemia and mosquito net use among school children across different settings in Kenya.

OBJECTIVE: To investigate risk factors, including reported net use, for Plasmodium infection and anaemia among school children and to explore variations in effects across different malaria ecologies occurring in Kenya. METHODS: This study analysed data for 49 975 school children in 480 schools surveyed during a national school malaria survey, 2008-2010. Mixed effects logistic regression was used to investigate factors associated with Plasmodium infection and anaemia within different malaria transmission zones. RESULTS: Insecticide-treated net (ITN) use was associated with reduction in the odds of Plasmodium infection in coastal and western highlands epidemic zones and among boys in the lakeside high transmission zone. Other risk factors for Plasmodium infection and for anaemia also varied by zone. Plasmodium infection was negatively associated with increasing socio-economic status in all transmission settings, except in the semi-arid north-east zone. Plasmodium infection was a risk factor for anaemia in lakeside high transmission, western highlands epidemic and central low-risk zones, whereas ITN use was only associated with lower levels of anaemia in coastal and central zones and among boys in the lakeside high transmission zone. CONCLUSIONS: The risk factors for Plasmodium infection and anaemia, including the protective associations with ITN use, vary according to malaria transmission settings in Kenya, and future efforts to control malaria and anaemia should take into account such heterogeneities among school children.

Plasmodium-helminth coinfection and its sources of heterogeneity across East Africa.

BACKGROUND: Plasmodium-helminth coinfection can have a number of consequences for infected hosts, yet our knowledge of the epidemiology of coinfection across multiple settings is limited. This study investigates the distribution and heterogeneity of coinfection with Plasmodium falciparum and 3 major helminth species across East Africa. METHODS: Cross-sectional parasite surveys were conducted among 28 050 children in 299 schools across a range of environmental settings in Kenya, Uganda, and Ethiopia. Data on individual, household, and environmental risk factors were collected and a spatially explicit Bayesian modeling framework was used to investigate heterogeneities of species infection and coinfection and their risk factors as well as school- and individual-level associations between species. RESULTS: Broad-scale geographical patterns of Plasmodium-helminth coinfection are strongly influenced by the least common infection and by species-specific environmental factors. At the individual level, there is an enduring positive association between P. falciparum and hookworm but no association between P. falciparum and Schistosoma species. However, the relative importance of such within-individual associations is less than the role of spatial factors in influencing coinfection risks. CONCLUSIONS: Patterns of coinfection seem to be influenced more by the distribution of the least common species and its environmental risk factors, rather than any enduring within-individual associations.

Preparing for national school-based deworming in Kenya: the validation and large-scale distribution of school questionnaires with urinary schistosomiasis.

OBJECTIVE: School questionnaires of self-reported schistosomiasis provide a rapid and simple approach for identifying schools at high risk of Schistosoma haematobium and requiring mass treatment. This study investigates the reliability of school questionnaires to identify such schools and infected children within the context of a national school-based deworming programme in Kenya. METHODS: Between November 2008 and March 2009, 6182 children from 61 schools in Coast Province, Kenya were asked by an interviewer whether they had blood in urine or urinary schistosomiasis (kichocho), and their results were compared with results from microscopic examination of urine samples. Subsequently, in 2009, a school-based questionnaire survey for self-reported schistosomiasis was distributed by the Ministry of Education to all schools in Coast Province, and its results were compared against results from the parasitological survey. The questionnaire survey results were linked to a schools database and mapped. RESULTS: Prevalence of self-reported blood in urine was lower among girls than boys among all ages. The use of a 30% threshold of reported blood in urine was both highly sensitive (91.7%) and specific (100%) in identifying high (>50%) prevalence schools in Coast Province. Questionnaires were however less reliable in diagnosing S. haematobium infection in individuals, particularly among young girls. Comparable levels of reliability were observed when the questionnaire was distributed through the existing education systems and administered by class teachers. CONCLUSIONS: The results confirm that blood in urine questionnaires can be reliably used to target mass treatment with praziquantel at national scales. The mapped results of the Ministry of Education survey serve to describe the spatial variation of urinary schistosomiasis and identify schools requiring mass treatment.

Spatial modelling of soil-transmitted helminth infections in Kenya: a disease control planning tool.

BACKGROUND: Implementation of control of parasitic diseases requires accurate, contemporary maps that provide intervention recommendations at policy-relevant spatial scales. To guide control of soil transmitted helminths (STHs), maps are required of the combined prevalence of infection, indicating where this prevalence exceeds an intervention threshold of 20%. Here we present a new approach for mapping the observed prevalence of STHs, using the example of Kenya in 2009. METHODS AND FINDINGS: Observed prevalence data for hookworm, Ascaris lumbricoides and Trichuris trichiura were assembled for 106,370 individuals from 945 cross-sectional surveys undertaken between 1974 and 2009. Ecological and climatic covariates were extracted from high-resolution satellite data and matched to survey locations. Bayesian space-time geostatistical models were developed for each species, and were used to interpolate the probability that infection prevalence exceeded the 20% threshold across the country for both 1989 and 2009. Maps for each species were integrated to estimate combined STH prevalence using the law of total probability and incorporating a correction factor to adjust for associations between species. Population census data were combined with risk models and projected to estimate the population at risk and requiring treatment in 2009. In most areas for 2009, there was high certainty that endemicity was below the 20% threshold, with areas of endemicity ≥ 20% located around the shores of Lake Victoria and on the coast. Comparison of the predicted distributions for 1989 and 2009 show how observed STH prevalence has gradually decreased over time. The model estimated that a total of 2.8 million school-age children live in districts which warrant mass treatment. CONCLUSIONS: Bayesian space-time geostatistical models can be used to reliably estimate the combined observed prevalence of STH and suggest that a quarter of Kenya's school-aged children live in areas of high prevalence and warrant mass treatment. As control is successful in reducing infection levels, updated models can be used to refine decision making in helminth control.

Implementing school malaria surveys in Kenya: towards a national surveillance system.

OBJECTIVE: To design and implement surveys of malaria infection and coverage of malaria control interventions among school children in Kenya in order to contribute towards a nationwide assessment of malaria. METHODS: The country was stratified into distinct malaria transmission zones based on a malaria risk map and 480 schools were visited between October 2008 and March 2010. Surveys were conducted in two phases: an initial opportunistic phase whereby schools were selected for other research purposes; and a second phase whereby schools were purposively selected to provide adequate spatial representation across the country. Consent for participation was based on passive, opt-out consent rather than written, opt-in consent because of the routine, low-risk nature of the survey. All children were diagnosed for Plasmodium infection using rapid diagnostic tests, assessed for anaemia and were interviewed about mosquito net usage, recent history of illness, and socio-economic and household indicators. Children's responses were entered electronically in the school and data transmitted nightly to Nairobi using a mobile phone modem connection. RDT positive results were corrected by microscopy and all results were adjusted for clustering using random effect regression modelling. RESULTS: 49,975 children in 480 schools were sampled, at an estimated cost of US$ 1,116 per school. The overall prevalence of malaria and anaemia was 4.3% and 14.1%, respectively, and 19.0% of children reported using an insecticide-treated net (ITN). The prevalence of infection showed marked variation across the country, with prevalence being highest in Western and Nyanza provinces, and lowest in Central, North Eastern and Eastern provinces. Nationally, 2.3% of schools had reported ITN use >60%, and low reported ITN use was a particular problem in Western and Nyanza provinces. Few schools reported having malaria health education materials or ongoing malaria control activities. CONCLUSION: School malaria surveys provide a rapid, cheap and sustainable approach to malaria surveillance which can complement household surveys, and in Kenya, show that large areas of the country do not merit any direct school-based control, but school-based interventions, coupled with strengthened community-based strategies, are warranted in western and coastal Kenya. The results also provide detailed baseline data to inform evaluation of school-based malaria control in Kenya.

The use of artemether-lumefantrine by febrile children following national implementation of a revised drug policy in Kenya.

OBJECTIVES: To examine access to, timing and use of artemisinin-based combination therapy among rural Kenyan febrile children before and following the introduction of artemether-lumefantrine (AL) as first-line antimalarial drug policy. METHODS: In August 2006, a cohort was established within 72 rural clusters in four sentinel districts to monitor the period prevalence of fever and treatment in children aged 0-4 years through four repeat cross-sectional surveys (one prior to introduction of AL and three post-AL introduction: January-June 2007). Mothers/guardians of children were asked about fever in the last 14 days and related treatment actions including the timing, drugs used, dosing and adherence supported by visual aids of commonly available drug products. RESULTS: A total of 2526 child-observations were recorded during the four survey rounds. The period prevalence of fever was between 20% and 26% with little variation between survey rounds. The overall proportion of children with fever receiving antimalarial drugs for their fever was 31 % (95% CI, 26-36%) and the proportion of febrile children receiving antimalarial drugs within 48 h was 23.3% (95% CI, 18.6-28.0%). The proportion of febrile children who received first-line recommended AL within 48 h was 10.2% (95% CI, 7.0-13.4%), compared to only 4.6% (95% CI, 3.8-5.4%) of children receiving sulphadoxine-pyrimethamine first-line therapy in 2001. CONCLUSIONS: Although Kenya was less than a year into the new policy implementation and AL is restricted to the public formal sector, access to antimalarial drugs among children within 48 h and to the first-line therapy has improved. But it remains well below national and international targets. The continued use of amodiaquine and artemisinin monotherapies constrains effective implementation of artemisinin-based combination therapy policy in Kenya.