Cholera in Yemen: A Case Study of Epidemic Preparedness and Response

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In 2015, the United Nations (UN) declared Yemen a Level 3 (L3) emergency. On September 28, 2016, a largescale cholera outbreak began. Between April 27, 2017 and July 1, 2018, more than one million suspected cases in two waves were reported. In the last decade, several large-scale and high mortality cholera outbreaks have occurred during complex humanitarian emergencies including in Iraq, Somalia, and South Sudan. While the issues of “what to do” to control cholera are largely known, context-specific practices on “how to do it” in order to surmount challenges to coordination, logistics, insecurity, access, and politics, remain. During the Yemen cholera outbreak response, questions arose concerning how to effectively respond to a cholera outbreak at a national scale during an existing L3 emergency. The Office of U.S. Foreign Disaster Assistance (OFDA), supported by the Department for International Development (DFID) and the European Civil Protection and Humanitarian Aid Operations (ECHO), provided funding to the Johns Hopkins Center for Humanitarian Health for an unsolicited proposal for a case study of the response.


The main objective was to identify lessons from September 28, 2016 to March 2018 (i.e., from the preparedness and detection phase to the end of second wave) to better prepare for future cholera outbreaks in Yemen and similar contexts. The methods included: literature reviews of global cholera guidance, cholera and other outbreak management in complex humanitarian emergencies and fragile states, and documents relating to the outbreak in Yemen; interpretation of surveillance data; and, key informant interviews (KII) with practitioners, donors, and technical experts involved in the response.


114 documents were reviewed, and 71 KIIs were undertaken.

  • Reports from Iraq, South Sudan, Haiti, and other complex emergencies and fragile states highlight substantial adaptations undertaken to manage cholera outbreaks. Global cholera guidance emphasizes the early detection and response to contain outbreaks at an early stage, a multi-sectoral approach to prevent cholera in hotspots in endemic countries, and effective mechanisms of coordination for technical support, resource mobilization, and partnership.

  • Prior to the outbreak, Yemen did not have a sufficient cholera preparedness and response plan. There was no plan despite previous cholera outbreaks, endemicity in the region, active conflict, and World Health Organization (WHO) regional office initiatives.

  • The 2016 cholera response plan evolved iteratively, but did not initially prioritize standard components. Initial gaps including epidemiological analysis to inform the response, and reference to the oral cholera vaccine, community surveillance, and infection prevention and control as well as emerging problems (e.g., improvement of laboratory capacity and monitoring of the application of the case definition).

  • The surveillance and laboratory systems were insufficiently prepared and inadequately modified to monitor the cholera epidemic during a complex emergency. The large number of suspect cases reported is likely much higher than the actual number meeting the suspect case definition. The lack of systematic use of culture-confirmation and the late adoption of epidemiological investigation and quality control made it difficult to address the high proportion of mild suspect cases. Extensive human resources and logistics were applied to sustain the response, proportionate to caseload, at a national level. Multiple contributing factors included: culture confirmation needs surpassing the capacity of the only two authorized laboratories; an incentive payment structure inadvertently promoted the inclusion of patients who did not meet the suspect case definition; and lack of early implementation of a system to remotely monitor reporting practices in insecure areas.

  • The treatment network of case management units (diarrhea treatment centers (DTCs) and oral rehydration corners (ORCs)) were insufficiently decentralized and did not ensure adequate access for as much of the population as could have been achieved. The strategy focused on establishing DTCs (both waves) and ORCs (second wave only) in or near existing health facilities, rather than being driven by placement near areas of epidemiological need and in more remote areas.

Decision-making was driven by the humanitarian need to integrate services due to a lack of human resources and functioning health centers. Despite the rapid scale of infection, technical guidance with attention to high-risk groups like pregnant women and children with severe acute malnutrition were provided with delay. Finally, there was limited focus on community-based approaches to treatment, referral and surveillance.

  • The water, sanitation and hygiene (WASH) sector was unprepared to transition from generalized development-style programming to choleraspecific activities. It was not until September 2017, after the peak of the second wave, that targeted, outbreak-specific rapid response teams (RRTs) were established, operationalized, and managed at the level of the 22 governorates, leading to specific WASH activities to reduce transmission. A late 2017/ early 2018 evaluation by the WASH cluster found that the majority of beneficiaries were reached through system support, including fuel, operations and maintenance support, rehabilitation, and sewage treatment plant support as opposed to choleraspecific interventions.

  • The use of the oral cholera vaccine (OCV) was slowed by the lack of cholera response planning and technical knowledge among the Ministry of Public Health and Population (MoPHP) and partners.

The lack of an updated cholera preparedness and response plan meant that OCV was not integrated into the response mindset and thus, there was a lack of technical knowledge and familiarly with OCV. OCV was not sufficiently discussed during the first wave, and was requested then rejected by the MoPHP during the second wave based on differing conceptions of the overall scale of distribution. The March 2018 plan is the first document that mentions an OCV strategy, based on a January 2018 risk assessment. The MoPHP then made a successful request to the Global Task Force for Cholera Control in April 2018 for 4.6 million doses for preventative use against future surges of cholera.

  • Three coordination systems operated with various success and limited complementarity. These included the health and WASH clusters and a Cholera Task Force (CTF) and followed by the implementation of the incident management system (IMS) and emergency operations centers (EOCs) led by WHO.

Coordination was also hampered by having two different governments in Yemen and political tensions.

  • Insecurity and airstrikes resulted in extensive damage to civilian infrastructure, including water systems. It likely contributed to service disruptions, reduced access to many areas of the country, and potentially increased cholera transmission. Other stressors included the closures of ports, airports and blockades of imported food, fuel, medications and medical supplies, and persistent ground-level insecurity.


The cholera response in Yemen was and remains extremely complicated and challenging for a variety of political, security, cultural, and environmental reasons. The study team recognizes these challenges and commends the government, international and national organizations, and the donors for working to find solutions in such a difficult context. There are no easy fixes to these challenges, and the conclusions and recommendations are meant to be constructive and practical, taking into account the extreme limitations of working in Yemen during an active conflict.

The findings were consistent across respondents and methods. The study team found that several areas gained strength throughout the second wave, including: an extensive operational footprint which reached into insecure areas; the strengthening of the collaborations between WHO and UNICEF and the health and WASH clusters; the initiation of a funding mechanism through the World Bank which enabled a timely response at scale; the revitalization of the WASH strategy; and, eventual consensus and use of OCV.

Conversely, the major gaps of this response are rooted in weaknesses in preparedness and the early strategies developed in the first wave. An after-action review after the first wave could have institutionalized these areas in order to prevent a much larger second wave.

The World Bank’s commitment to the cholera response provides the rationale for major investment in bolstering the preparedness activities in Yemen and other conflictaffected contexts which would go far for addressing the foundational gaps discussed in this case study.