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Source: http://www.alertnet.org/thenews/newsdesk/N11538600.htm
Mexican H1N1 flu spreads easily -study
11 May 2009 16:48:55 GMT
Source: Reuters
(For full coverage of the flu outbreak, click [nFLU])
*New strain may have originated in Mexican village
*More than 20,000 Mexicans likely infected
By Maggie Fox, Health and Science Editor
WASHINGTON, May 11 (Reuters) - The new strain of H1N1 flu that has killed 56 people in Mexico and been carried around the world by travelers appears to be more easily passed along than the regular seasonal flu, researchers reported on Monday.
As many as 23,000 Mexicans were likely infected with the swine flu virus, Neil Ferguson of Imperial College London and colleagues reported in the journal Science.
They also found evidence to support the theory that the outbreak originated in the village of La Gloria in the state of Veracruz, which had been the subject of intense speculation.
The international team, calling themselves the World Health Organization Rapid Pandemic Assessment Collaboration, looked at both the pattern of disease spread and the early genetic analysis of the virus.
"Our estimates suggest that 23,000 (range 6,000-32,000) individuals had been infected in Mexico by late April, giving an estimated case fatality ratio (CFR) of 0.4 percent based on confirmed and suspect deaths reported to that time," they wrote.
"Thus while substantial uncertainty remains, clinical severity appears less than that seen in 1918 but comparable with that seen in 1957."
The 1918 pandemic was the worst of the 20th century, killing anywhere between 25 million and 100 million people, depending on estimates. It was the first appearance of the H1N1 virus. The 1957 pandemic of H2N2 killed an estimated 2 million people globally. Seasonal flu kills about 250,000 to 500,000 people annually.
Looking at the pattern in La Gloria, the researchers said it looked as if the virus was transmitted human to human over 14 to 73 generations -- meaning one person infected another, who infected another, up to 73 times.
"Transmissibility is therefore substantially higher than seasonal flu," they wrote.
The first case was seen in La Gloria around February 15th, they wrote, citing reports and not hard evidence.
JAN 12 BIRTHDAY
Quick genetic analysis suggests the virus may have first infected someone around Jan. 12.
The researchers said other countries have had a better opportunity to watch out for the virus, a never-before-seen mixture of a Eurasian swine flu virus and a so-called "triple reassortant" virus seen circulating in pigs that includes some bits of human and bird flu viruses.
"As the epidemic spreads further, it is likely that severity will vary from country to country depending on health care resources and the public health measures adopted to mitigate impact," they added.
Globally, WHO has confirmed 4,694 infections in 30 countries with 53 deaths, all but four in Mexico. The United States has the most cases outside Mexico, with 2,618 cases and 3 deaths.
While it is widespread across the United States, WHO said the new H1N1 virus shows no signs of sustained person-to-person spread outside of North America. (Editing by Alan Elsner and Julie Steenhuysen)
Mexican H1N1 flu spreads easily -study
11 May 2009 16:48:55 GMT
Source: Reuters
(For full coverage of the flu outbreak, click [nFLU])
*New strain may have originated in Mexican village
*More than 20,000 Mexicans likely infected
By Maggie Fox, Health and Science Editor
WASHINGTON, May 11 (Reuters) - The new strain of H1N1 flu that has killed 56 people in Mexico and been carried around the world by travelers appears to be more easily passed along than the regular seasonal flu, researchers reported on Monday.
As many as 23,000 Mexicans were likely infected with the swine flu virus, Neil Ferguson of Imperial College London and colleagues reported in the journal Science.
They also found evidence to support the theory that the outbreak originated in the village of La Gloria in the state of Veracruz, which had been the subject of intense speculation.
The international team, calling themselves the World Health Organization Rapid Pandemic Assessment Collaboration, looked at both the pattern of disease spread and the early genetic analysis of the virus.
"Our estimates suggest that 23,000 (range 6,000-32,000) individuals had been infected in Mexico by late April, giving an estimated case fatality ratio (CFR) of 0.4 percent based on confirmed and suspect deaths reported to that time," they wrote.
"Thus while substantial uncertainty remains, clinical severity appears less than that seen in 1918 but comparable with that seen in 1957."
The 1918 pandemic was the worst of the 20th century, killing anywhere between 25 million and 100 million people, depending on estimates. It was the first appearance of the H1N1 virus. The 1957 pandemic of H2N2 killed an estimated 2 million people globally. Seasonal flu kills about 250,000 to 500,000 people annually.
Looking at the pattern in La Gloria, the researchers said it looked as if the virus was transmitted human to human over 14 to 73 generations -- meaning one person infected another, who infected another, up to 73 times.
"Transmissibility is therefore substantially higher than seasonal flu," they wrote.
The first case was seen in La Gloria around February 15th, they wrote, citing reports and not hard evidence.
JAN 12 BIRTHDAY
Quick genetic analysis suggests the virus may have first infected someone around Jan. 12.
The researchers said other countries have had a better opportunity to watch out for the virus, a never-before-seen mixture of a Eurasian swine flu virus and a so-called "triple reassortant" virus seen circulating in pigs that includes some bits of human and bird flu viruses.
"As the epidemic spreads further, it is likely that severity will vary from country to country depending on health care resources and the public health measures adopted to mitigate impact," they added.
Globally, WHO has confirmed 4,694 infections in 30 countries with 53 deaths, all but four in Mexico. The United States has the most cases outside Mexico, with 2,618 cases and 3 deaths.
While it is widespread across the United States, WHO said the new H1N1 virus shows no signs of sustained person-to-person spread outside of North America. (Editing by Alan Elsner and Julie Steenhuysen)
