PRAGUE, Sept. 6 (Xinhua) -- West Nile fever has appeared again in Czech after a several-year pause, Hana Zelena, an expert with the Czech National Reference Laboratory for Arboviruses, said on Thursday.

Zelena said an infected man stays in a hospital in Prague. The man returned from Greece in August and was taken to the infection clinic of Central Military Hospital (UVN) in Prague after suffering health troubles.

Zelena said the man's condition has worsened, he suffered from meningitis, including a temporary consciousness disorder. The doctors sent his sample for test, and confirmed it was West Nile fever.

West Nile fever is a serious disease spread by mosquitos. The Health Institute (ZU) in Ostrava is the only workplace in Czech that can reliably confirm the type of the infection.

The Ostrava ZU confirmed several imported cases of West Nile fever in the past, but the current case is the first one after several years.

There is another test, which has been underway to confirm the presence of antibodies. It needs one week to complete the test and the results will be known on next Tuesday. Zelena said she expects them to be positive.

Zelena said that only imported cases have occurred in the Czech Republic, which means that patients have been infected out of the country. However, she said the virus was repeatedly found in domestic mosquitoes, birds and even horses.