More than 85,000 cases of cholera in West and Central Africa are making this one of the region's most severe epidemics in recent memory.
Three simultaneous cross-border outbreaks are affecting people in two dozen countries along the coast from Guinea, and in the Lake Chad basin to the West Congo basin and around Lake Tanganyika. The World Health Organization says fatality rates in parts of Cameroon have topped 20 percent.
Cholera is endemic to West and Central Africa, where limited access to clean water and sanitation allows for easy transmission. But this current outbreak is especially widespread.
Grant Leaity, UNICEF's chief of emergency operations for West and Central Africa says the epidemic is due, in part, to a greater movement of people across the region.
"We have an increasing level of migration, more interstate trade and therefore movement of traders, truckers, fishermen, and this is where you can pick cholera up from one country and go put it in the next," he said.
It is especially difficult to monitor the spread of disease across remote borders such as the Lake Chad basin between Chad, Nigeria and Cameroon, he added. While aid agencies are working to improve cross-border disease surveillance, Leaity said stopping cholera starts with government health ministries improving prevention and treatment.
"Countries should have to actively engage in stamping out the disease," he said. "We are not going to be able to stamp this out purely with a regional or a cross-border approach.
"Cholera came from northeast Nigeria last year into extreme north Cameroon and then into Chad, [and] we have seen now that earlier this year we had cholera come from Ghana into Cote d'Ivoire," said Leaity. "We have seen more recently cholera come from Équateur and Bandundu provinces into Kinshasa and now it has gone from Kinshasa across the river into Brazzaville."
Despite its rapid spread, the World Health Organization says 90 percent of cholera cases and deaths are in just five countries: the Democratic Republic of Congo, Chad, Cameroon, Nigeria, and Ghana.