The H7N9 strain of bird flu in China that has killed more than 20 people this year has reached Taiwan, officials there confirmed Wednesday in announcing its first case of the deadly new strain.
The Centers for Disease Control and Prevention (CDC) said Wednesday that a 53-year-old man became ill with the H7N9 bird flu virus on April 9 after returning from a visit to the eastern Chinese province of Jiangsu. It did not identify him or provide details on his condition, except to say that he had suffered from a high fever for three days.
China and Taiwan have close trade and economic ties. An estimated 1 million Taiwanese live on the mainland and some 6,000 Chinese tourists visit Taiwan every day.
The H7N9 bird flu strain that emerged in China over the past month is one of the "most lethal" flu viruses so far, World Health Organization officials said Wednesday. Officials expressed concern because it can jump more easily from birds to humans than the strain that started killing people a decade ago.
Scientists are monitoring the virus closely to see if it could spark a global pandemic but say there is little evidence so far that it can spread easily from human to human.
Dr. Keiji Fukuda, WHO's top influenza expert, explained to reporters at a briefing in Beijing that people seem to catch the H7N9 virus from birds more easily than the H5N1 strain that began ravaging poultry across Asia in 2003. The H5N1 strain has since killed 360 people worldwide, mostly after contact with infected fowl.
Health experts are concerned about H7N9's ability to jump to humans, and about the strain's capacity to infect birds without causing noticeable symptoms, which makes it difficult to monitor its spread.
"This is definitely one of the most lethal influenza viruses we have seen so far," Fukuda said. But he added that experts are still trying to understand the virus, and that there might be a large number of mild infections that are going undetected.
The H7N9 bird flu virus has infected 108 people in China, Xinhua news agency and WHO reported Wednesday, 22 of whom died.
Most cases have occurred near the eastern coast around Shanghai.
In comparison, the earlier bird flu strain, H5N1, is known to kill up to 60 of every 100 people it infects.
Wednesday's briefing came at the end of a weeklong joint investigation by WHO and Chinese authorities in Beijing and Shanghai.
Experts said they still aren't sure how people are getting infected but said evidence points to infections at live poultry markets, particularly through ducks and chickens. They said it was encouraging that reported infections appeared to slow down after the closure of live poultry markets in affected areas.
International health officials have not requested any restrictions on travel to at this time.
"WHO does not advise special screening at points of entry with regard to this event, nor does it recommend that any travel or trade restrictions be applied," the organization said in a statement Wednesday.