The UN World Health Organization has urged Sudan to step up its efforts to halt the spread of Rift Valley Fever in the east of the country, where the viral disease has claimed almost 100 lives over recent weeks.

Sudan's acting health minister Al-Fateh Mohammed Saeed, however, said his ministry had been on alert for signs of the disease three weeks before an outbreak was declared and that the situation was now "quite stable".

According to a 14 November WHO update, 12 people died over a seven-day period in While Nile, Sinnar and Gezira States, and the number of reported cases of the disease increased to 329 from 228 a week before.

"Social mobilisation activities are now underway to alert the local population to the human health risks associated with this disease," WHO said. "However, more intensive efforts are urgently needed, using all locally available media, including television and radio channels, as well as community and religious leaders, to ensure that at-risk communities are fully aware of the measures that need to be taken to reduce the risk of human infection."

More than half of the current cases were reported from an area close to irrigation canals in Gezira, the update said, and were linked to naturally occurring cycles involving livestock and mosquitoes, which are abundant in the irrigation zone.

Saeed, in remarks quoted by the official Sudan News Agency, said White Nile state had not witnessed any new cases for three days, while Gezira had reported some and Khartoum one.

The news agency said Vice President Ali Osman Mohammed Taha, governors of the affected states and directors from the health and animal resources ministries agreed on 11 November to set up a mechanism to control the disease and regulate livestock movements.

Plans have since been drawn to limit such movements, intensify health awareness programmes and develop a national roadmap to eradicate the disease.

According to WHO, humans become infected through mosquito bites or direct contact with infected material and liquids such as animal blood shed during slaughtering. Uncooked milk of infected animals can also pose a risk, but no cases of human-to-human Rift Valley Fever transmission have been reported.

The UN Food and Agriculture Organization has deployed an expert to help Sudanese veterinary services, while WHO and the health ministry have presented a joint response plan to international donors in Khartoum.

The Egyptian Ministry of Agriculture has also instructed veterinary departments across the country to take all the necessary precautions against the disease, especially in the provinces bordering Sudan.

The outbreak was reported on 11 November by the Sudanese animal resources and fisheries ministry following the results of samples taken on 29 October from animals in White Nile state.