Dengue fever has killed at least 20 people in the West African state of Burkina Faso, where about 2,000 cases of the disease have been recorded.
Dengue is a mosquito-borne disease which is prevalent in sub-tropical and tropical regions.
It is a major cause of illness worldwide, causing about 100 million episodes of feverish illness a year.
Its outbreak in Burkina Faso is causing alarm and officials are trying to avoid any widespread panic.
One man told BBC Afrique's Yacouba Ouedraogo in the capital, Ouagadougou, that the disease had killed his brother quickly:
"My younger brother did not even have a chance to say what was wrong. We just found him dead," he said.
Dengue fever particularly affects young children and adults, but is not normally fatal, specialists say.
Most people who get it will suffer from headaches and fever. Some get rashes, aches and pains and their symptoms usually last for two or three days.
An infected person can feel tired for up to three months, but will not usually need treatment.
Cases of the disease have been reported from all 12 districts of Ouagadougou, the World Health Organization says.
Two other regions - the Sahel Region in the north and the Hauts-Bassins region in the west - have also reported cases.