Life Threatening; Starts like regular flu, then lungs stop functioning
China Daily, Reuters FilesA technician works in the inoculation area during preparations to produce vaccines for the H1N1 flu virus at a lab in Wuhan, Hubei province. Chinese vaccine maker Sinovac Biotech Ltd. hopes to put its ...
Anyone who develops serious flu-like symptoms should seek immediate medical attention, because no one can predict when the H1N1 flu virus, or swine flu, will turn life-threatening in otherwise healthy people, infectious disease experts are warning.
Severe cases are occurring, in which the infection starts off like regular seasonal flu, with fever and cough, but then the lungs rapidly become inflamed and stop functioning.
"It looks to most of us like a primary viral pneumonia that deteriorates five or six days into therapy," says Dr. Allison McGeer, director of infection control at Toronto's Mount Sinai Hospital. "It's really severe illness."
"If you're young and healthy, you can recover from that severe lung injury. People do. But it takes a very long time," Dr. McGeer said.
"Sometimes we're talking about a month, five weeks on a ventilator before you are breathing on your own. Some people can be left with so much residual lung damage, they will have abnormal lungs for their lifetime."
Scientists are scrambling to understand why otherwise healthy people are becoming seriously ill with swine flu.
But Dr. McGeer said attempting to identify whom this happens to "is the same as trying to pick out people who, faced with Group A [streptococcus], get necrotizing fasciitis -- flesh-eating disease -- when most of the rest of us get nothing, or minor illness," she said. "The parallel is, I think, identical.
"If you have underlying illness, if you are pregnant, there are things we know are risk factors," Dr. McGeer said.
"But I don't think there's anything that labels these people any more than there's something that labels people who get necrotizing fasciitis."
As of July 3, there had been 8,883 confirmed cases of the H1N1 flu virus across Canada, 663 of which have led to hospitalization, and 29 of which have ended in death.
And as the number of cases climb, H1N1 is showing signs that it can move outside the respiratory tract to other parts of the body, something regular flu viruses normally do not do.
Researchers from the Centers for Disease Control and Prevention in Atlanta found H1N1 virus in the small intestines of ferrets infected with HIN1 isolates taken from three people who developed mild, severe and fatal flu.
The finding could explain why swine flu is causing vomiting and diarrhea in about 40% of cases, symptoms that are not typical of garden-variety flu.
"That's not normal. Influenza should just be in the lung," said Earl Brown, an influenza expert at the University of Ottawa. "This is the first time a human flu has done this in a ferret. The question is: How does it get there? You don't like to see a flu virus move outside the lung."
The virus did not spread to other organs, such as the kidney or brain. But it suggests H1N1 influenza A is hardier and can survive in the environment longer than normal flu.
High amounts of the virus were also found in lung tissue, "which we don't typically see with seasonal strains," said Terrence Tumpey, a microbiologist at the Centers for Disease Control's influenza division.
They also found significant weight loss in the ferrets infected with the new swine virus.
"It tells us that this virus has the capability of causing more illness in mammals, in comparison to the seasonal strain," Dr. Tumpey said.
The ferret is considered the best model to study flu in humans. "Generally, the disease you get in the ferret mirrors the disease you get in humans," Dr. Brown, of the University of Ottawa, said.
Meanwhile, new, non-pandemic influenza has been found in two hog-farm workers in Saskatchewan, and a third case is under investigation.
The affected workers have fully recovered.
Yesterday, the World Health Organization said it has received more than 98,000 reports of laboratory-confirmed cases of pandemic H1N1 from 120 countries, including more than 440 deaths.
No comments:
Post a Comment