A cholera epidemic is spreading rapidly across West Africa, killing nearly 500 people and infecting thousands of others, United Nations officials warn.
The head of the UN humanitarian co-ordination office in the region said the outbreak needed a rapid response.
"It's not business as usual. We have a crisis that needs immediate attention," said Herve Ludovic de Lys.
With heavy rains across the region, cholera is likely to spread to Nigeria, Cameroon and Chad, the UN warns.
Guinea-Bissau is the worst hit country, with 9,047 infections and 172 deaths reported between June and August by the health authorities.
The country is desperately poor and has been through a period of political upheaval.
Many countries in the region are already hit by a food crisis
There was widespread flooding there Mr de Lys said, and with very few health facilities available outside the capital, cholera cases were being brought down to Bissau city, often delaying treatment until it was too late.
In Liberia there has been a major outbreak in Sinoe County in the south-east where nearly 4,000 cases have been reported, most of them in the makeshift camps where illegal miners dig for diamonds.
These camps lack clean drinking water and proper sanitation, creating dangerous conditions for cholera to spread.
Infections and deaths have also been reported in Mauritania, Guinea, Senegal, Burkina Faso, Mali, Ivory Coast and Niger.
Cholera is often transmitted by infected water and causes death by dehydration from diarrhoea and vomiting.
It can easily be treated if patients are rehydrated quickly and clean water supplies are available.