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- Title
Case-area targeted interventions during a large-scale cholera epidemic: A prospective cohort study in Northeast Nigeria.
- Authors
OKeeffe, Jennifer; Salem-Bango, Lindsay; Desjardins, Michael R.; Lantagne, Daniele; Altare, Chiara; Kaur, Gurpreet; Heath, Thomas; Rangaiya, Kanaganathan; Obroh, Patricia Oke-Oghene; Audu, Ahmadu; Lecuyot, Baptiste; Zoungrana, Timothée; Ihemezue, Emmanuel Emeka; Aye, Solomon; Sikder, Mustafa; Doocy, Shannon; Wang, Qiulin; Xiao, Melody; Spiegel, Paul B.
- Abstract
Background: Cholera outbreaks are on the rise globally, with conflict-affected settings particularly at risk. Case-area targeted interventions (CATIs), a strategy whereby teams provide a package of interventions to case and neighboring households within a predefined "ring," are increasingly employed in cholera responses. However, evidence on their ability to attenuate incidence is limited. Methods and findings: We conducted a prospective observational cohort study in 3 conflict-affected states in Nigeria in 2021. Enumerators within rapid response teams observed CATI implementation during a cholera outbreak and collected data on household demographics; existing water, sanitation, and hygiene (WASH) infrastructure; and CATI interventions. Descriptive statistics showed that CATIs were delivered to 46,864 case and neighbor households, with 80.0% of cases and 33.5% of neighbors receiving all intended supplies and activities, in a context with operational challenges of population density, supply stock outs, and security constraints. We then applied prospective Poisson space-time scan statistics (STSS) across 3 models for each state: (1) an unadjusted model with case and population data; (2) an environmentally adjusted model adjusting for distance to cholera treatment centers and existing WASH infrastructure (improved water source, improved latrine, and handwashing station); and (3) a fully adjusted model adjusting for environmental and CATI variables (supply of Aquatabs and soap, hygiene promotion, bedding and latrine disinfection activities, ring coverage, and response timeliness). We ran the STSS each day of our study period to evaluate the space-time dynamics of the cholera outbreaks. Compared to the unadjusted model, significant cholera clustering was attenuated in the environmentally adjusted model (from 572 to 18 clusters) but there was still risk of cholera transmission. Two states still yielded significant clusters (range 8–10 total clusters, relative risk of 2.2–5.5, 16.6–19.9 day duration, including 11.1–56.8 cholera cases). Cholera clustering was completely attenuated in the fully adjusted model, with no significant anomalous clusters across time and space. Associated measures including quantity, relative risk, significance, likelihood of recurrence, size, and duration of clusters reinforced the results. Key limitations include selection bias, remote data monitoring, and the lack of a control group. Conclusions: CATIs were associated with significant reductions in cholera clustering in Northeast Nigeria despite operational challenges. Our results provide a strong justification for rapid implementation and scale-up CATIs in cholera-response, particularly in conflict settings where WASH access is often limited. Jennifer OKeeffe and colleagues prospectively study the impact of case-area targeted interventions (CATIs) in Northeast Nigeria during the 2021 cholera outbreak to better understand how to successfully deploy and scale-up CATIs as a core response to future outbreaks. Author summary: Why was this study done?: Case-area targeted interventions (CATIs)—whereby teams deliver a mixture of health and water, sanitation, and hygiene (WASH) interventions to cholera case households and neighboring households within a predetermined radius—have become an increasingly common strategy to respond to cholera outbreaks. Existing research has suggested that CATIs can reduce the number of cholera cases, among other positive effects. However, such evidence stems from (1) modeling studies; (2) retrospective studies; or (3) controlled trials. A gap exists in prospectively studying CATIs in uncontrolled environments, a limitation that has hindered the deployment and scaling-up of CATIs as a core response to cholera outbreaks. What did the researchers do and find?: This study followed CATI teams during a large-scale cholera outbreak in Northeast Nigeria in 2021, collecting data on interventions provided, geospatial coordinates, demographics, and existing WASH infrastructure. Researchers used novel spatiotemporal methods to prospectively analyze the clustering of cholera cases in the presence of CATIs. Findings highlight that CATIs were associated with a reduction in cholera clusters during the outbreak; clusters were fewer and smaller, occurred for shorter duration, and were less likely to reoccur in the presence of CATIs. What do these findings mean?: CATIs can reduce cholera transmission in fragile settings, despite challenges such as high population density, supply stock outs, and security constraints. The study's novel methods, comprehensive scope, and expansion of previous research collectively strengthen our understanding of the value and applicability of CATIs in conflict-affected settings and supports their continued use and scale-up. Key limitations of this study include selection bias, remote data monitoring, and the lack of a control group.
- Subjects
NIGERIA; CHOLERA; RAPID response teams; COHORT analysis; LONGITUDINAL method; HEALTH facilities; EPIDEMICS
- Publication
PLoS Medicine, 2024, Vol 21, Issue 5, p1
- ISSN
1549-1277
- Publication type
Article
- DOI
10.1371/journal.pmed.1004404