Scientists in Desperate Race With Bird Flu
Will Killer Flu Bug Emerge Before We Are Ready?
Sept. 28, 2005 -- Bird flu has scientists on the edge of their seats about when and if it will become a human pandemic, a sobering report shows. That's the bad news.
The good news: Bird flu still doesn't spread easily among humans. Infected poultry was the source of virtually all of the 115 confirmed human infections with what scientists call H5N1 avian influenza. So far, only very few people seem to have caught it from other people, and then only after extremely close and sustained contact.
The bad news: More than half of the people who got bird flu have died. The true death rate for human cases of bird flu is not known. Mild cases don't show up in hospitals and don't get counted. But a new report on human bird flu infection shows that this is a very bad bug indeed.
The report comes from a May 2005 meeting of doctors and researchers held in Hanoi, Vietnam, by the World Health Organization. Among them is Frederick G. Hayden, MD, professor of clinical virology and internal medicine at the University of Virginia, Charlottesville.
"The news is concerning," Hayden tells WebMD. "Most cases are in apparently healthy adults and children. About half of them die from what appears to be a viral pneumonia, sometimes with secondary bacterial infections. Some suggest this virus behaves differently from human flu."
Hayden and colleagues' report appears in the Sept. 29 issue of The New England Journal of Medicine.
Bird Flu: Early Symptoms, Frequent Death
Even though people obviously do get bird flu from poultry, it's not something that happens often. Millions of domestic chickens and ducks have been infected. Yet relatively few people show evidence of infection, notes flu expert John Treanor, MD, professor of medicine and director of the vaccine and treatment evaluation unit at the University of Rochester in New York.
"When you think of the totality of human experience with infected poultry, fewer than 150 cases is only a small number," Treanor tells WebMD. "The opportunities for whatever needs to happen for this to spread among humans have been, thankfully, quite limited."
The earliest symptom of bird flu is a lot like that of human flu: a sudden high fever. After that, the symptoms tend to be different. Bird flu patients only sometimes have a runny nose. They tend to have lower respiratory symptoms, especially cough and shortness of breath. Other early symptoms may include diarrhea, vomiting, abdominal pain, lung pain, and bleeding from the nose and gums.
There may also be symptoms highly unusual for flu. Two patients had brain infections and diarrhea but not respiratory symptoms.
Typically, about five days after illness onset, patients have shortness of breath. Severe breathing problems are common; there may be bloody sputum. Patients often progress to acute respiratory distress in about six days, which requires oxygen therapy and may require assisted breathing with a machine. Multiple organ failure is common. Death usually comes from respiratory failure.
The disease has been particularly deadly for children. In Thailand, 89% of patients under the age of 15 years died an average of nine or 10 days after illness onset.