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Researchers rush to solve flu mystery
December 17, 1997
A possibility that the disease may spread through human contact concerns health officials
CNN's Dr. Steve Salvatore explains the concerns about the flu, whether it could spread, and how to prevent it
1 min. 30 sec. VXtreme video
Web posted at: 10:03 a.m. EST (1503 GMT)In this story:
HONG KONG (CNN) -- There's a race against time in the virus lab of the Hong Kong Health Department, where a team of researchers, aided by experts from the U.S. Centers for Disease Control, is struggling to identify and track a new and potentially deadly strain of influenza known as "bird flu" or "chicken flu."
The virus, previously found only in birds and poultry, has infected seven people and is suspected of infecting two others in Hong Kong. Patients in two of the confirmed cases have died.
The latest suspected cases, young cousins of a 5-year-old girl suffering from the disease, raised fears that the virus, with the scientific name H5N1, could be spread from person to person.
Hong Kong health director Margaret Chan said information collected from the seven confirmed cases indicated that some patients had contact with poultry while others had not. She said this suggests that transmission of the virus both from bird-to-human and human-to-human may be possible.
How does it spread?
Bridges collects blood samples to be analyzed by the CDC Thousands of blood samples and throat swabs have been collected. Dr. Carolyn Bridges, one of the CDC researchers working on the mystery, says some of the material will be sent back to the United States to test for antibodies to H5N1.
While it is possible that both bird-to-man and man-to-man transmission has taken place, "it is occurring at a low level," Chan said. "But we are very concerned with this cluster of cases."
There's good reason for that. The last flu pandemic that originated in Hong Kong, in 1968, cost tens of thousands of lives around the world.
"The reason it is of such big concern," said Dr. Keiji Fukuda, another CDC researcher, "is that influenza viruses are almost unique in their ability to rapidly spread around the world. Because they infect such large numbers of people, the numbers of people that get sick and can die from those infections is very high."
But even with so much at stake, solving this medical mystery is proving to be anything but easy.
"There's only been a handful of cases that we know about, so we don't know how much is out there," said Dr. Joseph Bresee of the CDC. "Part of the epidemiological studies that we are doing is identifying just that question."
Where did it come from?
In addition to doing lab work, researchers seek more information about poultry farms in rural Hong Kong, where thousands of chickens died suddenly of the H5N1 virus last spring. Soon after, the first human cases were reported.
It's also possible the virus originated in mainland China, which provides the majority of chickens sold in Hong Kong markets. But there is a lack of detailed information about poultry farm conditions there. Beijing says it has not taken any particular measures to protect against the mystery flu.
Hong Kong health officials say they're happy with Beijing's cooperation. "I'm pretty confident the Chinese side can monitor the disease," said K.K. Liu of Hong Kong's Agriculture and Fisheries Department.
Privately, though, some experts say that on the mainland, bureaucratic inefficiency and the sheer scale of the monitoring job mean that nobody really knows what is happening.
That's one key reason why Hong Kong authorities have stepped up inspections of poultry shipments from the mainland, part of a series of measures to block the spread of the disease. Tightened hygiene standards and a public education campaign also have been implemented.
Finding an effective vaccine
Knowing where the virus started and how it is transmitted is just part of the puzzle. Scientists also are concerned that H5N1 might be able to change itself, becoming resistant or even immune to vaccines as it spreads.
"One of the defining characteristics of influenza viruses is that they change a lot," Fukuda said. "Even though (H5N1) is inefficient at this point, it could become more efficiently transmitted either to humans or among humans in the future."
In that case, the next step will be to develop a vaccine, a process that won't be easy. "All flu virus vaccines are produced from chicken embryos. For this virus, it kills chick embryos, so we will have to find another means, " said Dr. Raymond Yung, a microbiologist.
For those on the medical front lines, the bird flu mystery is a source of genuine, and growing concern. But doctors point out that the flu virus is extremely unpredictable. And it remains entirely possible H5N1 could infect a few more people here, and then simply disappear.
Hong Kong Bureau Chief Mike Chinoy contributed to this report.
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Related stories:
- Shalala gets a read on new flu - December 16, 1997
- Hong Kong 'chicken flu' suspected in 2 more cases - December 16, 1997
- Hong Kong poultry market shut amid fears of bird flu - December 15, 1997
- Doctors hunt for source of deadly 'bird flu' strain - December 8, 1997
Related sites:
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- Hong Kong Department of Health - official site
- Centers for Disease Control
- National Food Safety Database
- World Health Organization
External sites are not endorsed by CNN Interactive.
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