As we gear up for a potential new round of H1N1, aka swine flu, it is worth noting some of the other health complications of human-pig encounters.
Sporadic transmission of endemic influenza strains found in pigs in not new, but other viral infections have been equally a cause for concern. Hepatitis E, for example, is a disease that had been limited to developing countries and tightly linked to poor sanitation. That presumption fell by the wayside when blood tests in swine farmers and other pig handlers from industrialized nations revealed that Hepatitis E infection occurs relatively frequently among such workers. Although generally milder than Hepatitis A or B, Hepatitis E can be life threatening, in particular during pregnancy.
Nor is that the only other pig-associated emerging infection. In the 1990's there was an outbreak of yet another non-influenza viral disease called Nipah among pig farmers in Maylasia. This was no common cold or even a mild hepatitis. Nipah virus causes lethal brain infection.
Closer at hand, however, the U.S has had its own home-grown outbreak of severe neurological disease among swine slaughterhouse workers. The first cases occurred in a Minnesota processing plant (http://www.cdc.gov/mmwr/preview/mmwrhtml/mm57e131a1.htm). All were linked to the factory's "head table" where swine brains were processed using compressed air to liquefy the tissue (known among the workers as "blowing brains"). Two other U.S. facilities in the United States that also used compressed air for blowing brains, one in Indiana and one in Nebraska, later reported similar cases.
The specific cause of the new syndrome, progressive inflammatory neuropathy (PIN), has not yet been identified. PIN does not seem to be due to an infectious cause. It may be that pig brain proteins, put into the air by the compressed air, cause an auto-immune response when inhaled by humans. The use of compressed air in pig processing has now been stopped, but the illnesses that this practice induced appear to be long lasting.
Before they ever get to the slaughterhouse, the industrial methods commonly used to raise pigs commercially (here and abroad) have also been host to their own problems. Massive enclosed facilities holding large numbers of livestock, called swine confinement buildings, trap high levels of irritant fumes and dusts and produce large volumes of bio-wastes, occupational and environmental threats in turn. They may also be the breeding grounds of future health threats that could be with us long after H1N1 has come and gone.