Eliminating Cholera Transmission in Haiti

Friday, 9th of December 2016

Eliminating Cholera Transmission in Haiti

Louise C. Ivers, M.D., M.P.H.

December 7, 2016DOI: 10.1056/NEJMp1614104

Excerpt below; full text, with references, is at http://www.nejm.org/doi/full/10.1056/NEJMp1614104?query=TOC

When Hurricane Matthew struck on October 4, 2016, it left 1.4 million people in southern Haiti in need of urgent humanitarian assistance; it destroyed homes and health care facilities, flooded water sources with runoff, ruined crops, killed livestock, and displaced hundreds of thousands of people. Looming as the next act in the disaster is a resurgence in endemic cholera.

Cholera had not been recorded in Haiti until it was introduced in 2010. The introduction of Vibrio cholerae into a population that had never been exposed to cholera and that had extremely limited access to safe water and sanitation had a predictable effect: an explosive cholera epidemic that has killed at least 10,000 people and caused nearly 800,000 reported cases throughout the country.1

Now in its seventh year, the epidemic has taken an immeasurable toll on individuals, communities, and the health system in Haiti, and the resources for controlling it have been too limited. In 2015, Haiti reported more cases of cholera per population than any other country. In 2016, there were 29,000 cases of cholera in the first 9 months of the year — already a disaster before the hurricane hit. And as is so often the case, the poor have suffered the most. New approaches are needed to address the ongoing problem and mitigate suffering from cholera in Haiti. The hurricanes aftermath adds urgency to this problem.

On October 13 and 14, 2016, the minister of health and population of Haiti, Daphnee Benoit, convened an expert panel at the U.S. National Institutes of Health to consult on the control of cholera in Haiti with specific reference to the use of vaccines in the aftermath of Hurricane Matthew. Two weeks after Hurricane Matthew, the number of cholera cases had grown, and many were concerned about the impact on human life. The consultation resulted in the following consensus.

The response to Hurricane Matthew must first and foremost address the victims need for humanitarian relief, through provision of food, shelter, and clean water to those who lack these lifesaving essentials. Rallying emergency clean-water activities to combat the known risk of cholera in the immediate phase is an important strategy. We should assume, at least initially, that there has been further contamination of freshwater sources in the southern peninsula. Ensuring that people have access to and use effectively chlorinated water, with safe water storage at home (or in shelters), is a critical lifesaving objective.

There is a simultaneous need to ensure that cholera treatment centers and oral rehydration posts are functional. After the hurricane, many of these facilities will have to be rebuilt; resupplied with rehydration fluids, antibiotics, and zinc for children; and supported with staff to perform effective case finding in the community and rapid treatment of the sick. These strategies have not changed since the beginning of the cholera epidemic in 2010, although in recent years resources to implement them have dwindled.

When the cholera epidemic began in Haiti, and for some years afterward, there was a lack of consensus on the role that oral cholera vaccine (OCV) could play in the response. One clear issue, however, was that the supply of vaccine was very limited, and there was limited experience in using OCVs in response to outbreaks. Furthermore, the fact that the most affordable vaccine had not yet met prequalification requirements of the World Health Organization (WHO) meant that the United Nations Childrens Fund (UNICEF) and other United Nations agencies could not purchase it.

Since that time, a number of developments have enhanced our ability to control the epidemic in Haiti. Two safe, effective OCVs are now available at an affordable cost ($1.70 to $1.85 per dose), are prequalified by the WHO, and are available in increasing quantities. The products are essentially the same vaccine, made by different manufacturers. Shanchol (Shantha Biotechnics, India) was prequalified in 2011. In 2013, a 2-million-dose OCV stockpile was established as a public good to manage the vaccine. Euvichol (Eubiologics, South Korea) was prequalified by the WHO in 2015, and the manufacturer recently announced that it could produce 25 million single-dose vials per year that remain stable at 37°C for 30 days, avoiding waste and enabling delivery to the most remote areas without requiring a stringent cold chain. Other OCVs are available (VaxChora, PaxVax, United States; Dukoral, Valneva, Sweden) but at this time are not considered practical for major public health use in resource-poor settings.

Finally, a series of studies with OCVs in Haiti have demonstrated the efficacy of the Shanchol vaccine in both urban and rural settings, the feasibility of achieving high coverage rates, and the low cost of delivering this vaccine to the population. In one of the poorest urban slums of Haiti, not a single case of culture-confirmed cholera occurred between September 2013 and August 2016 in persons who had received a combined intervention ensuring household chlorination and cholera vaccination.2-4 This research complements other recent OCV studies from Guinea and South Sudan.

This information fundamentally changes the way health authorities should now consider the use of OCV in controlling cholera. Mass vaccination in Haiti would save lives, and modeling suggests that such an intervention, coupled with targeted, effective water, sanitation, and hygiene interventions, could substantially control, if not eliminate, the disease within a few years of the programs introduction, at an affordable cost. This medium-term plan will have to be undertaken in concert with a long-term effort to realize the human right of access to clean water, a goal that will require a substantial budget and years, if not decades, to accomplish. Control of cholera was a problem in Haiti for the 6 years before Hurricane Matthew — not only because there were insufficient resources, but also owing to the enormity of the challenge of redressing the populations severely constrained access to clean water and sanitation.