Could recent hurricanes cause reemergence of cholera in Puerto Rico?

The Caribbean has a long history with cholera, a severe diarrheal illness associated with high mortality. Throughout the 19th century, cholera epidemics were relatively common and were noted to occur in three waves associated with global pandemics.

During this period there was a confluence of factors promoting disease in the Caribbean, including the degraded health conditions linked to the Atlantic slave trade and colonial rule, as well as frequent contact with individuals or groups arriving from Europe, Africa and elsewhere. In 1855-56 Puerto Rico experienced a major cholera outbreak, despite local efforts to undertake preventive measures, including quarantine.

The emergence of cholera in Haiti in 2010 is a poignant reminder that the Caribbean remains susceptible to outbreaks. Specifically with respect to Puerto Rico, there are several potential concerns.

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A 1989 study published in Applied and Environmental Microbiology found Vibrio cholerae bacteria in the Mameyes River, a tropical rain forest watershed on the northeastern coast of Puerto Rico. Presumably V. cholerae could be recovered elsewhere on the island, although I’m not aware of studies that differentiate between pathogenic and non-pathogenic strains of the bacterium.

Another key factor is poverty because of its association with low sanitation, inadequate access to clean water and low-quality housing. According to the U.S. Census, of the 3.4 million people living in Puerto Rico, approximately 43.5 percent live in poverty, representing about 1.5 million people.

In that setting, Hurricane Maria has knocked out over 90 percent of the island’s power grid and a humanitarian emergency is unfolding, according to Puerto Rico’s governor. Of particular relevance to cholera, it was reported this week that 60 percent of the population may not have access to clean water.

These factors – the presence of the V. cholerae bacterium, poverty, collapsed infrastructure and lack of potable water access – create a toxic mix that could promote cholera outbreaks in Puerto Rico during the coming days and weeks. In a paper published in 2008, B. Christenson wrote that “Puerto Rican water sources can maintain their pathogenic potential for sporadic or erratic toxigenic cholera outbreaks – if a ‘perfect storm’ ever occurs.”

Hurricanes Maria and Irma might indeed be those perfect storms. We therefore need to take this risk seriously and take urgent measures to prevent the emergence of cholera as well as other catastrophic enteric diseases, including typhoid.

Such activities would include ensuring the widespread availability of potable water, implementing programs of sanitation, health system strengthening and active disease surveillance. Some of these actions may require U.S. military and National Guard support, and it is likely that local health departments on the island will require additional support, including technical assistance from the CDC. Such measures represent worthwhile investments to protect our American citizens living in Puerto Rico.

-By Peter Hotez, M.D. Ph.D., dean of the National School of Tropical Medicine at Baylor College of Medicine and director of Texas Children’s Hospital Center for Vaccine Development

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