Rift Valley Fever has killed 92 people in Sudan since reports of an outbreak surfaced a week ago and it is still spreading, the World Health Organisation (WHO) says.
The UN body has started holding daily meetings to monitor the spread of the disease, which has no effective human vaccine and can kill as many as half of those who contract it.
A WHO spokeswoman said the latest figures showed 314 known human cases in Sudan, up from 228 reported six days ago, with a death rate of just under 30 per cent.
In its most serious form, which has appeared in Sudan, it can kill up to 50 per cent of people it infects.
The disease can also have a devastating effect on livestock.
People who work with animals are most vulnerable to the disease, which can spread through contact with contaminated blood or bites from infected mosquitoes.
The UN Food and Agriculture Organisation (FAO) said it had sent an animal health expert to Sudan to help the government contain any outbreak in livestock.
It said Sudan had already reported some animal infections to the Paris-based World Organisation for Animal Health.
Khartoum denied making any such report on Wednesday.
The ministry of animal resources said there were no confirmed cases in herds despite the outbreak among humans.
Reports in the daily newspaper Alray Alam said a number of Sudan's trading partners, including Saudi Arabia and the United Arab Emirates, had imposed temporary bans on imports and the movement of Sudanese animals over their borders.