An outbreak of an avian bird flu that has attacked flocks of turkeys continues to spread throughout the Mississippi River Valley, as biosecurity detectives scramble to pin down the mode of transmission and contain the epidemic.
Three states reporting an outbreak – Minnesota, Arkansas and Missouri – share the potential culprit. That would be the Mississippi River, which serves as a major flyway for migratory waterfowl. The particular strain of avian influenza usually doesn’t harm wild fowl, but does cause problems for domesticated flocks. The outbreak along the Mississippi flyway involves the same virus that has infected the Pacific flyway, where South Korea, for one, has watched the outbreak spread to 2.6 million birds.
Most food birds raised in the US are kept indoors, in large part to limit exposure to viral agents. Now, at least some US biosecurity experts believe the migrating fowl may have left behind droppings that could have been tracked into sanitary facilities on the rubber boots of farmworkers.
So far in the US, two commercial flocks have had to be destroyed after farmers found evidence of the flu among their birds. Kansas imposed a quarantine of flocks in two counties bordering the river.
The chances of bird-to-human transmission, however, is effectively nil, according to Dirk Haselow, the Arkansas state epidemiologist. The main concern for poultry-importing nations is not that the flu will hurt people, but could cause dramatic losses in domestic flocks.
“There is no risk to the public and there are no food safety concerns,” Dr. Haselow told reporters. “No one is ill and turkeys from this farm are not entering the food supply.”
Still, the stakes are high for farmers scrambling to contain the virus. The flu wiped out tens of thousands of birds at a commercial turkey farm in Minnesota last month. The outbreak is also having an effect on global trade. On Thursday, Mexico, which imports more chicken from the US than any other country, put into place new restrictions on US-bred poultry.
Flyways can be particular breeding grounds for the flu. After originating in Asia, the current form of the flu branched out into different forms along the Pacific flyway, as birds from different parts of the globe communed along the extra-territorial bird highways that guide fowl to and from their winter and summer grounds.
Turkeys act as a sort of canary in the coal mine for such outbreaks, since they are far more vulnerable than other kinds of birds.
The US Department of Agriculture claimed this week that the US has “the strongest [avian influenza] surveillance program in the world,” and that the agency is working with partners “to actively look for the disease in commercial poultry operations, live bird markets, and in migratory wild bird populations.”
So far, those efforts, which include six-mile radius quarantines around affected farms, seem to be paying off. "At least right now we're breathing a little easier," Missouri Department of Agriculture Director Richard Fordyce told the Associated Press.