Mapping of cholera hotspots in Kenya using epidemiologic and water, sanitation, and hygiene (WASH) indicators as part of Kenya’s new 2022–2030 cholera elimination plan

Abstract

Cholera is an issue of major public health importance. It was first reported in Kenya in 1971, with the country experiencing outbreaks through the years, most recently in 2021. Factors associated with the outbreaks in Kenya include open defecation, population growth with inadequate expansion of safe drinking water and sanitation infrastructure, population movement from neighboring countries, crowded settings such as refugee camps coupled with massive displacement of persons, mass gathering events, and changes in rainfall patterns. The Ministry of Health, together with other ministries and partners, revised the national cholera control plan to a multisectoral cholera elimination plan that is aligned with the Global Roadmap for Ending Cholera. One of the key features in the revised plan is the identification of hotspots. The hotspot identification exercise followed guidance and tools provided by the Global Task Force on Cholera Control (GTFCC). Two epidemiological indicators were used to identify the sub-counties with the highest cholera burden: incidence per population and persistence. Additionally, two indicators were used to identify sub-counties with poor WASH coverage due to low proportions of households accessing improved water sources and improved sanitation facilities. The country reported over 25,000 cholera cases between 2015 and 2019. Of 290 sub-counties, 25 (8.6%) sub-counties were identified as a high epidemiological priority; 78 (26.9%) sub-counties were identified as high WASH priority; and 30 (10.3%) sub-counties were considered high priority based on a combination of epidemiological and WASH indicators. About 10% of the Kenyan population (4.89 million) is living in these 30-combination high-priority sub-counties. The novel method used to identify cholera hotspots in Kenya provides useful information to better target interventions in smaller geographical areas given resource constraints. Kenya plans to deploy oral cholera vaccines in addition to WASH interventions to the populations living in cholera hotspots as it targets cholera elimination by 2030.

Spatial and temporal analysis of cholera cases in high-risk areas of Kenya

“…Among these clusters, Dadaab and Fafi sub-counties stood out as the most significant, with a Relative Risk of 28.37 and a P-value <0.0001. This finding agrees with a previous study conducted on cholera hotspot mapping in Kenya using the GTFCC model, which also identified Dadaab as a high-risk sub-county (Kiama et al, 2023). Furthermore, similar findings have been reported in previous studies conducted in Ghana, Nigeria and Bangladesh, indicating the presence of possible spatial and temporal clustering of cholera (Ngwa et al, 2021; Debes et al, 2016;Osei & Duker, 2008).…”

“…During the study period, annual cholera epidemics followed a recurring pattern of waxing and waning, indicating a cyclicality in the occurrence of cholera outbreaks over time. In Kenya, these epidemic cycles have previously been reported to occur approximately every five to seven years lasting for two to three years (Kiama et al, 2023). In the current study, cholera cases waxed every three years in the selected high-risk areas.…”

“…The camp has a population of approximately 240,984 people, primarily refugees from Somalia (UNHCR operational portal, 2023). These areas were purposively selected because of their increased risk to cholera outbreaks due to overcrowding, inadequate access to clean water as well as poor sanitation and hygiene (Kiama et al, 2023; Mills et al, 2011; Bene & Neiland, 2003). A map of the study area is shown in Figure 1.…”

“…Since 1971 when the first outbreak was reported in Kenya, a number of significant cholera outbreaks have been reported (Kigen et al, 2020;Mutonga et al, 2013; Scrascia et al, 2009; Shikanga et al, 2009; Mugoya et al, 2008 ; Shapiro et al, 1999; Tauxe et al, 1995). Recent estimates show that up to 4.9 million people live in cholera prone areas in Kenya commonly known as hot spots (Kiama et al, 2023). The 2022 outbreak in Kenya was reported in 25 (53%) counties according to the Cholera outbreak situational reports by Kenya’s Ministry of Health (https://reliefweb.int/report/kenya/kenya-cholera-outbreak-operational-update-appeal-no-mdrke054-22-july-2023).…”

Comparison of analysis methods to classify cholera hotspots in Ethiopia from 2015 to 2021

“…With this method, priority areas are identified based on three epidemiological parameters (cumulative incidence, cumulative mortality and cholera persistence, as defined above) and a cholera test positivity indicator 13 . In addition to these three main methods, other country-specific ad-hoc classification methods have been implemented using a combination of different epidemiological indicators and contextual cholera risk factors 14 – 16 . To date, no study has compared the three main cholera hotspot classification methods to adapt targeting strategies.…”