The first cases of suspected the viral hemorrhagic fever were reported in the area in early September. These are the first cases of Rift Valley fever reported outside traditionally affected areas in Africa.

The World Health Organization and other international groups are taking measures to try to control the spread of the disease. Spokesman Valery Abramov says W-H-O advises travelers to Yemen and Saudi Arabia to take certain precautions.

Abramov: W-H-O advises that people can travel freely to and from both countries. However, precautions should be taken. That is persons traveling within the affected districts should wear long-sleeved shirts and trousers and should use mosquito repellent and bed nets and avoid contact with ill livestock.

Rift Valley fever is a disease that primarily affects animals, but occasionally causes disease in humans. People may become infected by being bitten by infected mosquitoes or through contact with the blood, other body fluids, or organs of infected animals. It may cause severe disease in both animals and humans, sometimes leading to death.

The disease is named after the Rift Valley of Kenya where the virus was first isolated in 1930. W-H-O says studies are being carried out to find out what may have triggered the outbreak of the disease in Saudi Arabia and Yemen.