BBC NEWS | Africa | Disease alert in flood-hit Africa
Severe flooding across Africa has wrecked hundreds of thousands of homes and left many people vulnerable to water-borne diseases, officials say.
Scores of people have died and much of the continent's most fertile farmland has been washed away in what is being described as a humanitarian disaster.
The UN said more rain was expected and warned that the need for food, shelter and medicine was urgent.
Some 17 countries have been affected in West, Central and East Africa.
( These include: Senegal, Mali, Burkina Faso, Liberia, Ghana, Togo, Nigeria, Niger, Chad, Sudan, Ethiopia, Uganda, Kenya and Rwanda )
UN spokeswoman Elisabeth Byrs said: "The rains are set to continue and we are really concerned because a lot of people are homeless and infectious diseases could emerge.
"Some of the poorest countries, like Mali, Burkina Faso and Niger - the poorest nation in the world - are badly affected."
The UN said the floods could lead to locust infestations and outbreaks of diseases such as cholera and dysentery.
Countries in East Africa regularly flood at this time of year, but West African nations are much less able to deal with the deluge, the World Food Programme says.
"In Kenya or Ethiopia, these countries are facing floods every year and year after year, they have set up some contingency plans," the WFP's Pierre Lucas told the BBC.
"In West Africa, the level of awareness is not the same, and the response capacity [is] really different."
Ghana has been hit badly by the flooding, with three northern regions being declared an official disaster zone after whole towns and villages were submerged.
Information Minister Oboshie-Sai Cofie said: "It is a humanitarian disaster. People have nowhere to go. Some of them are just hanging out there waiting for help to come."
She said the Ghanaian government had received considerable aid and hoped the situation would improve.
French military helicopters were helping relief efforts in nearby Ivory Coast, while officials in Togo were dealing with more than 60,000 displace people and a wrecked infrastructure.
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A related story:Cholera Strikes Again in Guinea
Endemic in West Africa, cholera has once again struck in Guinea. The arrival of the rains at the end of May, notably in the capital, Conakry, has created an ideal breeding ground for the disease to spread. Faced with an increasing number of cases, Doctors Without Borders/Médecins Sans Frontières (MSF) has boosted its direct support of the local health services.
Since January this year, nearly 2,500 cases of cholera have been recorded in and around Conakry. Ninety people have died from the disease. After only a few hours, infected people can become dehydrated and die. Simple medical care consisting of oral rehydration or a perfusion, depending on the state of the patient and in some cases antibiotics, are enough to help patients quickly recover.