WHO casts wary eye on meat, blood of H1N1-infected pigs

"While it is possible for influenza viruses to survive the freezing process and be present on thawed meat, there are no data available on the survival of Influenza A/H1N1 on meat nor any data on the infectious dose for people," he wrote in an email reply to questions from Reuters concerning the safety of pork, respiratory secretions and blood of H1N1-infected pigs.

Schlundt warned people to be cautious with blood and meat-juices from H1N1-infected pigs.

"The likelihood of influenza viruses to be in the blood of an infected animal depends on the specific virus. Blood (and meat-juice) from influenza H1N1-infected pigs may potentially contain virus, but at present, this has not been established," Schlundt said.

"Nonetheless, in general, we recommend that persons involved in activities where they could come in contact with large amounts of blood and secretions, such as those slaughtering/eviscerating pigs, wear appropriate protective equipment," he said.

The new H1N1 swine flu virus is being transmitted from person to person, not from pigs to people.

Its global spread has prompted many countries to limit pork imports, however. As many as 20 governments have imposed import bans on live pigs and meat from affected countries to prevent exposure to the virus. Such fears increased after Canadian authorities said on Saturday a herd of swine was infected by a farmer who had returned from Mexico.

The WHO said 22 countries have officially reported 1,534 cases of the flu virus.

While health officials say the outbreak appears to be slowing down in Mexico, authorities everywhere are asking how far the virus would spread and how serious it would be.

U.S. officials confirmed that a Texas woman with the H1N1 swine flu virus died earlier this week, the second death outside Mexico. Last week, a Mexican toddler visiting Texas died. Mexican officials have reported 29 confirmed deaths.