Climate Change is Increasing Incidence of a Cholera-​Like Disease in the U.S.

October 9/2019

by Françoise Makanda, Communications Officer at DLSPH

A new study led by DLSPH alumnae found that the United States is experiencing a rise in vibriosis, an infectious disease caused by cholera-like bacteria, and rising sea temperatures from climate change are likely to blame.

Vibriosis infections are caused by the same bacteria genus as cholera, called Vibrio. Infection can result in diarrhea, or severe skin infections, which can cause death, especially in those with weakened immune systems. Vibrio bacteria can be found in contaminated seafood or saltwater. American authorities have reported increasing rates of vibrio in recent decades.

Rebecca Ling (left) and Chloe Logar-Henderson (right) found that the United States is experiencing a rise in vibriosis, an infectious disease caused by cholera-like bacteria, and rising sea temperatures from climate change are likely to blame.

“The incidence of vibriosis has been on the rise but the reasons remain unclear. One explanation may be the connection to climate change and its effect on warming ocean temperatures, which are ideal conditions for growing Vibrio bacteria,” says Rebecca Ling, the study’s co-lead.

Study-leads took an interest in vibriosis given how little research is focused on the bacteria compared to its sister bacteria, cholera.

As part of the communicable epidemiology course taught by Prof. David Fisman, the former students took an unusual approach to collecting the data. Ling and Logar-Henderson used publicly available CDC data, presented as graphs and maps, to obtain case information over the 15-year period of their study.

The researchers used a third-party program to extract vibriosis case counts from CDC reports.

“It was a unique approach to data collection since we couldn’t obtain the data through other means,” says Ling. “But, you can still produce meaningful output.”

Co-author, Chloë Logar-Henderson, says that the study does not account for changes in reporting over time or specific case information such as route of exposure or potential comorbidities. But, the data supports a link between rising sea surface temperatures and incidence of vibriosis. Similar findings in recent literature have found a link between warming sea-surface temperatures to an increase of vibriosis in the Baltic region of Europe.

“The number of cases emerging over time in the Pacific and Gulf area is greater because the water temperature is warmer which is favourable for the bacteria. People are usually doing water-related activities in these areas, which is one of the main routes of exposure for these bacteria,” says Logar-Henderson.

Given the warming oceans, Logar-Henderson and Ling anticipate that the burden of the disease will increase in coming years. The study could help guide and prioritize preventative strategies and predict future patterns of other waterborne disease, including cholera and Legionnaire’s disease.