At least 27 Burundian refugees fleeing weeks of political violence have died of cholera in Tanzania, the United Nations said, warning more could die without urgent action.
Over 110,000 Burundians have become refugees since unrest erupted in their country in April, according to the UN refugee agency. More than 70,000 have gone to Tanzania, over 26,000 to Rwanda, and over 9,000 to Democratic Republic of Congo.
"The unrest has forced more than 110,000 people to flee to neighboring countries," the UN children's agency said. "Most are women and children, and the majority of them have arrived in Tanzania, where a cholera epidemic has so far killed 27 people," it added.
The crisis, which began in late April after the ruling party nominated President Pierre Nkurunziza to stand for a controversial third term in June presidential elections, deepened last week when a top general staged a failed coup attempt.
In Kaguna, the western Tanzanian border town with Burundi, on the shores of Lake Tanganyika, over 50,000 refugees are struggling in dire conditions.
The site is isolated, with refugees camping on the shore awaiting boats to take them further south to the port of Kigoma.
"Children make up more than half the population and they are particularly vulnerable to cholera," UNICEF regional chief Leila Pakkala-Gharagozloo said.
Oxfam has warned the risk of disease is "dangerously high", and that "clean water, medical care and proper sanitation are urgently needed."
In Kaguna, Oxfam is working to install water taps and latrines, warning the flood of people is "a ticking time bomb for disease", with over a thousand cases of acute watery diarrhea.
"Children under five are most at risk, and with no access to clean drinking water, and next to no sanitation, it is a life-threatening situation for many," the charity said.
Refugees are being transported on a century-old German warship turned ferry that inspired the book and film "The African Queen", hired by the United Nations High Commissioner for Refugees to carry some 600 passengers at a time.
The vessel was once a feared gunboat defending the African lake for Kaiser Wilhelm II during World War I, but today it is a lifeline for refugees.