GENEVA, Nov 8 (Reuters) - An outbreak of Rift Valley Fever in Sudan has spread, killing 84 people out of 228 known cases, the World Health Organisation (WHO) said on Thursday.

The toll was up from 60 deaths among 125 people a week ago, according to the United Nations agency which has been working with Sudan's health ministry since it sought help in October.

Fifteen sites in White Nile, Sennar and Jazeera provinces in central and eastern Sudan are now affected by the disease, which is transmitted by contact with the blood or organs of infected animals, the WHO said in a statement.

The Rift Valley Fever virus can also be carried by mosquitos. Herders, farmers, veterinarians and slaughterhouse workers are deemed at higher risk of infection from the disease, which can devastate livestock.

There is no specific treatment or effective human vaccine, so it is important to raise awareness of risk factors and ensure people take protective measures to prevent exposure, the WHO said. Gloves and other protective clothing should be worn when handling sick animals or their tissues or when slaughtering.

Animal products including blood, meat and milk should be thoroughly cooked before eating, it said. Humans should also sleep under mosquito nets and wear long-sleeved shirts and trousers to protect against bites.

While most human cases are relatively mild, a small percentage of patients develop a much more severe haemorrhagic form which can cause them to vomit blood or pass it in their faeces. Bleeding from the nose or gums can also occur.

(Reporting by Stephanie Nebehay; editing by Diana Abdallah)

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