TAIYUAN -- A total of 17 people have died from encephalitis B after being bitten by mosquitoes in Yuncheng, a city in north China's Shanxi Province in the last two weeks, local health authorities said Friday.

The city's health bureau said so far they have found at least 40 cases of the disease, including the 17 dead.

The disease is mostly epidemic in Yuncheng's counties of Linyi, Yongji and Ruicheng along the Yellow River, said Lu Shuanguo, deputy head of the bureau.

The official said most of the encephalitis B sufferers are people at the age from 50 to 70 and few children have been found to be infectious.

Six experts from China Disease Prevention and Control Center, sent by China's Ministry of Health, arrived at Yuncheng on Friday, seeing the patients and collecting some sample of the virus for investigation.

They are working with the Shanxi Provincial Health Department on urgent measures to prevent the spread of the deadly disease, according to local sources.

Encephalitis is an inflammation of the brain that can occur at any age and is usually the result of a viral infection. It may begin with a flu-like illness or a headache.