El Nino can warn on cholera outbreaks in Africa: study
El Nino, the cyclical climatic phenomenon in the Pacific Ocean, is linked to shifts in cholera cases in Africa, providing an early warning that could save lives, scientists said Monday.
During the years when El Nino is warming the eastern Pacific, East Africa has about 50,000 additional cholera cases a year, new research from the Johns Hopkins Bloomberg School of Public Health suggests.
By contrast, the years when El Nino is not active, there were 30,000 fewer cholera cases in East Africa, according to the study published Monday in the journal Proceedings of the National Academy of Sciences.
The researchers analyzed more than 17,000 annual observations from 3,710 different locations between 2000 and 2014 in Africa, which has the most cholera deaths in the world.
The total number of cases of cholera across Africa as a whole were about the same in El Nino years as compared with non-El Nino years, but the geographic distribution of illnesses was "fundamentally different," the study's authors said in a statement.
In total, 177 million people live in Africa in the regions where cholera cases spike with El Nino, and even triple in certain areas.
Cholera is an infectious bacterial disease that can be fatal. It is typically caught from infected water supplies, resulting in severe vomiting and diarrhea.
"We usually know when El Nino is coming six to 12 months before it occurs," said study leader Justin Lessler, an associate professor of epidemiology at the Bloomberg School.
"Knowing there is elevated cholera risk in a particular region can help reduce the number of deaths that result," he said.
"If you have cholera treatment centers available, fast, supportive care can reduce the fatality rate from cholera from as high as 30 percent to next to nothing."
El Nino conditions in the equatorial Pacific strongly impact weather conditions globally, including increasing rainfall in East Africa and decreasing rainfall in drier areas of northern and southern Africa.
In some areas, heavy rainfalls can cause sewers to overrun and contaminate drinking water.
In other parts of Africa, the dry conditions can make clean water sources less available and people are force to consume water from contaminated sources, the researchers noted.
There is a vaccine against cholera but its protection is not lifelong. In addition, there is not enough supply of the vaccine to cover the populations in the African regions where the incidence of cholera is linked to El Nino.