Effectiveness of Case-Area Targeted Response Interventions Against Cholera: A Quasi-Experimental Study in Haiti

Abstract

Background - Case-area targeted interventions (CATIs) conducted by rapid response teams are recommended by the Global Task Force on Cholera Control (GTFCC) to contain cholera outbreaks. They may include various combinations of water, sanitation, and hygiene measures, prophylactic antibiotics, and/or oral cholera vaccine. However, their effectiveness has never been established in a real-world setting. Haiti has implemented CATIs as a national coordinated strategy against cholera since July 2013. Methods - We thus conducted a quasi-experimental study from January 2015 to December 2017 in the Centre department of Haiti. Using case and stool cultures records, together with daily CATI reports of mobile teams, we identified and characterized cholera outbreaks at the locality scale, and then studied the outcome of outbreaks according to the response promptness. First, we compared the number of cases from the 4th day of outbreak between classes of time to the first complete CATI using generalized linear mixed models. Second, we compared the duration of outbreaks using Cox models for Andersen-Gill counting process. CATI effectiveness estimates were adjusted for potential confounders. Findings - We identified 456 cholera outbreaks across 290 different localities, including 176 responded to by at least one complete CATI. Compared to a first complete CATI >7 days after outbreak onset, a first complete CATI ≤1 day reduced accumulated cases by 74% (58 to 84), and outbreak duration by 64% (42 to 78). Interpretation - These results strongly suggest that a coordinated CATI strategy was significantly effective in mitigating and shortening cholera outbreaks in Haiti. Further research is required to confirm such findings, to study the respective effectiveness of each CATI component, to economically evaluate CATI efficiency and to better position CATI with other cholera control tools in a multi-sectoral approach. Funding - United Nations Children's Fund (UNICEF)-Haiti and Assistance Publique - Hopitaux de Marseille (APHM). Declaration of Interest: Authors working for the United Nations Children's Fund, Haiti (UNICEF-Haiti): SB, GB UNICEF-Haiti worked with the Haitian Ministry of Health and Population (MSPP) to implement the CATI response strategy against cholera in Haiti. For this, UNICEF-Haiti received funds from ECHO (European Commission Humanitarian Office), DFID (UK Government's Department for International Development) and CERF (Central Emergency Response Funds of United Nations). These three institutions had no involvement in study design, collection analysis and interpretation of data, in the writing of the report, and in the decision to submit the paper for publication. Authors working for Assistance Publique – Hopitaux de Marseille (APHM): JG, SR, RP (until 2017) Authors working for Assistance Publique – Hopitaux de Paris (AP-HP): RP (since 2017) AP-HP, a French university-hospital, has been mandated by the Haitian Ministry of Health and UNICEF-Haiti, and granted by UNICEF-Haiti, to provide the CATI response strategy against cholera with prospective epidemiological analyses and evaluations. Authors working for Ministry of Public Health and Population (MSPP): EM, JB, PD To implement the CATI response strategy against cholera in Haiti, MSPP has received material and financial support from UNICEF-Haiti. This study aimed to present and assess this strategy. Author with 335 no competing interest: MP Ethical Approval: The study protocol received authorization #1718-24 from the National Bioethics Committee of Haiti MSPP