Warm spring weather is the surest cure for the worst outbreak of avian influenza to hit the U.S. poultry industry in three decades, said USDA chief veterinarian John Clifford. Some 7.3 million chickens, turkeys and other poultry in 13 states have been infected or killed by the flu, or destroyed as a precaution against spread of the virus. Minnesota, the No. 1 turkey state, has recorded 41 cases.
“When we see warm weather consistently across the country, we will stop seeing new cases,” said Clifford during a telephone news conference. “We know this virus doesn’t like heat.” Sunny days will help, too, said David Swayne, director of the USDA’s Southeast Poultry Research Lab. Ultraviolet light destroys viruses.
Sixty percent of the outbreaks – including detection of bird flu on an Iowa egg farm with 3.8 million laying hens – occurred in the past two weeks, despite repeated warnings to poultry farmers to step up sanitation standards. Officials believe the disease is being spread by droppings from migrating wildfowl. “We are looking into a multitude of possibilities,” such as wind-blown contaminated dirt and feathers, for how the virus entered poultry barns, said Clifford. Many of the facilities are located near lakes where waterfowl are present.
The USDA listed 13 new cases on Wednesday, all in Minnesota, totaling more than 430,000 turkeys.
Dr. Alicia Fry of the Centers for Disease Control said DNA tests of the avian influenza virus found no genetic markers associated with human susceptibility. There have been no cases of human infection and the CDC is “cautiously optimistic” there won’t be, said Fry. “At least 100 [farm workers] have been monitored with no human cases.”
Many export markets have closed to U.S. poultry meat as a result of the outbreaks. The USDA estimates U.S. poultry exports will fall by 8.5 percent because of import restrictions in countries such as China and South Korea, two major customers. Mexico banned imports of live birds and eggs from Iowa following the outbreak there, said Reuters.
The USDA is working on a potential vaccine against the current strain of bird flu, said Swayne. “It’s a multi-step process,” and a different USDA agency would decide if it will be used. “We have a potential seed strain.” Fry said the CDC, as a matter of course with any viral disease, has identified a potential seed virus for a human vaccine but has not proceeded further.
So far, avian influenza has been confirmed only in the western half of the country. “We can’t predict what will happen in the fall,” said Swayne. The virus might burn out among wildfowl during the summer. If it appears during the fall migration, it could be in any or all of the four flyways crossing the country, said Clifford.
As far as a vaccine for poultry, the USDA will begin animal tests in May, said the Associated Press, but there are questions how widely a vaccine would be used, and how much it would cost.
Avian influenza has had a minor impact on U.S. poultry production. Around 9 billion broiler chickens are marketed annually from 30,000 chicken farms. Growers produce around 250 million turkeys a year. There are around 300 million laying hens.