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Bird Flu Detected in Three People in Iowa, Study Finds
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Amitabh Avasthi
for National Geographic News
July 31, 2006
A duck hunter and two wildlife workers in Iowa have tested positive for a nonlethal form of avian flu, according to a team of U.S scientists. Their study is the first to suggest that bird flu can be transmitted to humans from wild birds.
"We did not detect H5N1, the virus that has caused such a high death rate in the humans it has infected," said the study's lead author, James Gill, who is a disease specialist at the University of Iowa Hygienic Laboratory in Iowa City.
Instead the researchers found that the infection was caused by the H11 virus, a strain commonly found in ducks, geese, and shorebirds but not previously associated with human illness.
The study was conducted as part of ongoing surveillance efforts to track diseases that could be transmitted from animals to humans.
(See National Geographic magazine's "Tracking the Next Killer Flu.")
The research involved 39 duck hunters and 68 wildlife experts from the Iowa Department of Natural Resources.
Their blood serum was tested for traces of antibodies against the influenza virus. Antibodies are signs of infection.
"Our research found that one duck hunter and two of the wildlife professionals had been infected with the H11 virus, likely caught from wild waterfowl," Gill said.
The findings appear in the August issue of the journal Emerging Infectious Diseases.
Virus Mutated?
It is still not clear what possible adaptations the H11 virus may have undergone to infect the human hosts or how exactly it may have spread to them.
"We did not isolate the virus from the three infected persons. Our [test] was designed to detect antibodies in their blood," Gill said.
He says that the H11 virus may have an increased ability to infect humans, but the virus also may have been spotted now due to better detection techniques.
"There are numerous strains of influenza circulating in birds, and it is possible more such strains may be detected in future," Gill said. <!--- deckend --->
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While the animals themselves may not get sick, people in close proximity to wild birds could be at risk, he adds.
"Wildlife frequently carries potential human pathogens," Gill said. "This study demonstrates that the handling of wild waterfowl, such as ducks and geese, is a risk factor to human health."
But he notes that such infections can be prevented.
"Humans [should] wear gloves when handling wild animals and then wash or thoroughly clean their hands afterwards. They should also avoid smoking or eating while handling wild animals."
Circumstantial Evidence?
Robert Atmar, an infectious disease physician at Baylor College of Medicine in Houston, Texas, says he thinks there are several problems with Gill's study.
"This is an interesting paper, but there isn't enough information to draw any firm conclusions," he said.
"For starters, the study fails to explain the specificity of the [test]. The presence of antibodies could mean there was an infection, or it could be a false positive. There is no way of knowing."
Atmar also suggests that the study might have been more accurate if the researchers had included subjects who had had no exposure to birds. "The lack of a control group makes it difficult to say anything. The findings are intriguing but largely circumstantial," he said.
http://news.nationalgeographic.com/n...tml?source=rss
Amitabh Avasthi
for National Geographic News
July 31, 2006
A duck hunter and two wildlife workers in Iowa have tested positive for a nonlethal form of avian flu, according to a team of U.S scientists. Their study is the first to suggest that bird flu can be transmitted to humans from wild birds.
"We did not detect H5N1, the virus that has caused such a high death rate in the humans it has infected," said the study's lead author, James Gill, who is a disease specialist at the University of Iowa Hygienic Laboratory in Iowa City.
Instead the researchers found that the infection was caused by the H11 virus, a strain commonly found in ducks, geese, and shorebirds but not previously associated with human illness.
The study was conducted as part of ongoing surveillance efforts to track diseases that could be transmitted from animals to humans.
(See National Geographic magazine's "Tracking the Next Killer Flu.")
The research involved 39 duck hunters and 68 wildlife experts from the Iowa Department of Natural Resources.
Their blood serum was tested for traces of antibodies against the influenza virus. Antibodies are signs of infection.
"Our research found that one duck hunter and two of the wildlife professionals had been infected with the H11 virus, likely caught from wild waterfowl," Gill said.
The findings appear in the August issue of the journal Emerging Infectious Diseases.
Virus Mutated?
It is still not clear what possible adaptations the H11 virus may have undergone to infect the human hosts or how exactly it may have spread to them.
"We did not isolate the virus from the three infected persons. Our [test] was designed to detect antibodies in their blood," Gill said.
He says that the H11 virus may have an increased ability to infect humans, but the virus also may have been spotted now due to better detection techniques.
"There are numerous strains of influenza circulating in birds, and it is possible more such strains may be detected in future," Gill said. <!--- deckend --->
<!--- start major_NEWSCHOOL_ENLARGE.html ---><!-- GOING_NEWSCHOOL_ENLARGE -->
Enlarge Photo
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While the animals themselves may not get sick, people in close proximity to wild birds could be at risk, he adds.
"Wildlife frequently carries potential human pathogens," Gill said. "This study demonstrates that the handling of wild waterfowl, such as ducks and geese, is a risk factor to human health."
But he notes that such infections can be prevented.
"Humans [should] wear gloves when handling wild animals and then wash or thoroughly clean their hands afterwards. They should also avoid smoking or eating while handling wild animals."
Circumstantial Evidence?
Robert Atmar, an infectious disease physician at Baylor College of Medicine in Houston, Texas, says he thinks there are several problems with Gill's study.
"This is an interesting paper, but there isn't enough information to draw any firm conclusions," he said.
"For starters, the study fails to explain the specificity of the [test]. The presence of antibodies could mean there was an infection, or it could be a false positive. There is no way of knowing."
Atmar also suggests that the study might have been more accurate if the researchers had included subjects who had had no exposure to birds. "The lack of a control group makes it difficult to say anything. The findings are intriguing but largely circumstantial," he said.