Chlorinating wells, improving sanitation and boosting knowledge of how the disease is spread would help cut the spread of cholera, experts say.
The U.N. said West African countries so far reporting cholera infections and deaths are Guinea-Bissau, Liberia, Mauritania, Guinea, Senegal, Burkina Faso, Mali, Ivory Coast and Niger — epicenter of the region's deadly food crisis.
Farther south, a cholera outbreak among soldiers and their families in eastern Congo killed at least 19 people and sickened over 700 in recent days.
The worst-hit country in West Africa, per capita, is the former Portuguese colony of Guinea-Bissau, where nearly 1 percent of the country's 1.5 million people have fallen ill with cholera.
After years of civil conflict and poor governance, the country's health care system is in shambles. Health authorities have reported 9,047 infections including 172 deaths between June 6 and August 21.
Hardest hit are residents of the crumbling capital, Bissau, where bullet holes still pock buildings and tanks lay rusting alongside roads after the country's 1998-1999 civil war.
The U.N. said Guinea-Bissau's situation could worsen.
"If nothing happens, we could have an unimaginable toll," said John Mulangu, a top regional official of the U.N.'s World Health Organization.
Increased funding and health care material for treatment and prevention efforts are needed, the officials said.
"It's a focal point and we need to pay attention to avert a humanitarian disaster," said Mulangu.