2013-04-02

Pandemic Fears

Is This a Pandemic Being Born?
According to Chinese authorities, some of the dead pigs tested antibody-positive for circoviruses, or PCV-2, and samples of the virus were isolated from Huangpu River. The implication was that the Shanghai pigs died of PCV-2, a type of virus that is harmless to human beings, as well as birds. Photographs of the carcasses reveal that the animals were large adult hogs, but PCV-2 does not kill adult pigs -- it is lethal to fetuses and newborn piglets.

The Chinese health authorities have to date offered no cause of death for the ducks and swans, failed to describe any unusual genetic features that might have turned the PCV-2 into an adult pig-killer virus, and insisted there is no connection between the pigs, people, and birds. Though the surviving woman, Han, had some contact with live chickens, according to Xinhua, neither Li nor Wu had any known contact with birds. Wu has been identified variously as a butcher, meat processor, and employee of a meat plant -- all of which might imply he had contact with pigs.

Influenzas are named according to the specific nature of two proteins found on the virus -- the H stands for hemaggluntinin and the N for neuraminidase. These proteins play various roles in the flu-infection process, including latching onto receptors on the outside of the cells of animals to transmit the virus into their bodies. Those receptors can vary widely from one species to another, which is why most types of influenza viruses spreading now around the world are harmless to human beings. As far as any scientists know, the H7N9 forms of flu have never previously managed to infect human beings, or any mammals -- it is a class of the virus found exclusively in birds. It is therefore extremely worrying to find two people killed and one barely surviving due to H7N9 infection.

...If the pigs, people, and birds have died in China from H7N9, it is imperative and urgent that the biological connection be made, and extensive research be done to determine how widespread human infection may be. Shanghai health authorities have tested dozens of people known to have been in contact with Wu and Li, none of whom have come up positive for H7N9 infection. Assuming the tests are accurate, the mystery of Li and Wu's infections only deepens. Moreover, if they are a "two of three," meaning two dead, of three known cases, the H7N9 virus is very virulent.

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