TORONTO – A cholera outbreak in the world’s largest refugee camp in Kenya has now killed at least 12 people and sickened over 1,500 amid rains linked to El Niño.

Health workers and humanitarian agencies fear cholera will spread to other camps and refugee settlements in East Africa when the rainy season starts next month.

Cholera, a water-borne bacterial illness transmitted through contaminated drinking water causes fever, vomiting and watery diarrhea, flared up in November in Kenya’s Dadaab and Alinjugar camps. The first victim was a boy who had played in contaminated water pools at the camps, which house 348,000 refugees and asylum-seekers, the majority who have fled violence in neighbouring Somalia.

In Dadaab and other refugee camps and settlements in the region, there have been outbreaks in 2011, 2013 and 2014, but were always isolated cases that could be stopped immediately.

Neighbouring counties in Kenya have also been effected by cholera, as well as next-door Tanzania. But, camps and other temporary settlements are at higher risk due to the limited drinking water and sanitation infrastructure.

“From Ethiopia to Haiti to Papua New Guinea, we are seeing the damage from El Niño, and we believe the impact on public health is likely to continue throughout 2016, even after El Niño winds down,” warned Dr Richard Brennan of the World Health Organization (WHO) last month. “To prevent unnecessary deaths and illnesses, governments must invest now in strengthening their preparedness and response efforts.” Doctors Without Borders (MSF) recently added cholera as one of the five epidemics to look out for in 2016.

The current El Niño from 2015 to 2016 is predicted to be the worst in recent years, and comparable to the El Niño in 1997-1998, which had major health consequences globally.

El Niño is a weather pattern caused by Pacific Ocean warming. It has brought massive droughts to parts of Eastern and Southern Africa, while countries around the Great Lakes region like Kenya, Tanzania and Uganda face unusually heavy rainfall and flooding.

Increased displacement in the Great Lakes region, including people fleeing conflicts in Burundi and Mozambique, has also put displaced peoples camps in neighbouring countries like Malawi at risk. “Clearly, places that are overcrowded are at higher risk,” said Dr. Dominique Legros, cholera focal point at WHO’s Department for Pandemic & Endemic Diseases in a telephone interview.

The cholera outbreak in Dadaab is now under control and has not reached other major refugee camps settlements in Kakuma (northeastern Kenya), Nairobi and Mombassa. An outbreak control team from the UN refugee agency UNHCR and partners has worked with the Kenyan Health Ministry and Department of Refugee Affairs officials to treat cases and stamp out the disease at the sprawling Dadaab complex with increased levels of chlorine, which kills cholera-causing bacteria, at water points in the camps. Better hygiene, especially the use of latrines and hand washing with soap, has been promoted through hourly public announcements. Each refugee also received 250-gram bars of soap with the latest food distribution, and this will continue monthly for several months, according to Mr. Duke Mwancha, spokesperson for UNHCR in Kenya.

Now the emphasis will be on prevention. In January, WHO approved a third cholera vaccine in order to increase its global stockpile. These vaccines can contribute to preventing outbreaks among populations living in high-risk areas, where usual control measures are not sufficient. The vaccine was pre-emptively administered in refugee camps in Tanzania after one outbreak.

“The vaccine is not the silver bullet, it is a new tool to help,” said Dr. Monica Rull, operational health advisor for MSF in Geneva. There is a limited stock of the cholera vaccines. It is mainly used during humanitarian emergencies when it is administered pre-emptively, as in Tanzania last year, or reactively to contain an outbreak, as is now being done in new refugee camps in Malawi. Both Dr. Rull and Dr. Legros emphasize that the vaccines are to be used in combination with traditional cholera control measures. “It’s vaccine and awareness raising and access to safe water and treatment of patients,” said Dr. Legros.

Cholera is a disease that spreads very quickly. “If you want to contain an outbreak […] you really need to detect it as soon as possible,” said Dr. Legros.

WHO will organize a regional meeting with the ministries of health, humanitarian agencies and political leaders in Nairobi next month to review the response to cholera outbreaks and how to prepare for future responses.