Saudi Arabia's mystery virus traced

The disease is usually spread by mosquitoes

An outbreak of an illness which has killed at least 16 people in the Saudi province of Jizan has been identified as Rift Valley Fever (RVF).

According to the World Health Organisation (WHO) this is the first report of the disease outside Africa.

The virus usually affects animals, but can be transmitted to humans via mosquitoes, or through coming into contact with the blood of contaminated animals.

A spokesman for the Saudi health authorities said the disease had been transmitted by sheep and a large number of animals had died recently in Jizan.

Bleeding

He said 16 of the 36 people infected had now died, but no new cases had been reported in the last 48 hours.

The authorities in Jizan province imposed emergency measures after cases of the disease were detected

The disease can cause bleeding from the mouth, ears and nose, eye lesions and encephalitis but symptoms more usually resemble those of influenza.

Malnutrition and poverty contribute to mortality rates

Human mortality rates in outbreaks are usually low, but hundreds died in Kenya and Somalia after the disease spread widely during floods.

Saudi Arabia regularly imposes bans on the import of livestock from countries suffering outbreaks of Rift Valley Fever in order to prevent the spread of the disease.

Jizan province lies around 300km from the coast of Africa across the Red Sea.

It is one of the poorest parts of Saudi Arabia, where most people live off fishing and livestock.

The farming population lives in round huts made of branches and often sleep outdoors because of the heat.

The town of Jizan is known for its heat and humidity at this time of year which, combined with recent seasonal heavy rains, makes it an ideal breeding ground for mosquitoes.