Bird flu outbreak spreads among US cattle, scientists searching for cause

AMES, Iowa — At first glance, it looks like any other farm: Cows dot the fenced fields, there's a milking shed in the distance, and a tractor parked next to it. But no farmer is working there, and the other buildings look more like a modern college than a cow ranch.

Welcome to the National Animal Disease Center, a government research facility in Iowa where 43 scientists study pigs, cows and other animals to try to solve the avian flu currently spreading across the United States. Animals of the United States — and develop ways to stop it.

Of particular importance are: Bovine Vaccine Designed to stop continuity Spreading the virus The hope is that this will one day reduce the risk of the disease spreading among humans.

The United States Department of Agriculture (USDA) facility opened in 1961 in Ames, a college town about 45 minutes north of Des Moines. The center is located on 523 acres (212 ha) of rural land a few miles east of downtown Ames in the city's lowlands.

It's a quiet place, but one with a rich history. Over the years, researchers here have developed vaccines against a variety of diseases that endanger pigs and cattle, including hog cholera and brucellosis, and in 2009, research during the H1N1 influenza pandemic, then called “swine flu,” proved that the virus was confined to the respiratory tract of pigs, and pork was safe to eat.

Dr. Richard Webby, a prominent influenza researcher at St. Jude Children's Research Hospital in Memphis, said his center has special resources and experience to conduct such studies.

“That's not a capability that many facilities in the U.S. have,” said Webby, who has collaborated with the Ames facility on cattle vaccine research.

The campus has 93 buildings, including a highly-contained laboratory building that resembles a modern megachurch from the outside but has a series of compartmentalized corridors and rooms inside, some of which house infected animals, where scientists work with more dangerous germs, such as the H5N1 avian flu, a three-story office building that houses animal-disease researchers, and a testing center that's an “animal version” of the CDC lab in Atlanta that identifies rare (and sometimes frightening) new human infections.

About 660 people work on campus, about a third of them at the Animal Disease Center, which has an annual budget of $38 million and is already busy with a variety of projects, but has become even busier this year because of the sudden spread of H5N1 avian flu among U.S. dairy cows.

“It's really amazing to see people persevere and make progress,” said Dr. Mark Ackerman, director of the center.

The virus was first identified in 1959 and posed a widespread and deadly threat to migratory birds and domestic poultry, but in recent years it has evolved and has been detected in an increasing number of animals, from dogs and cats to sea lions and polar bears.

Despite being widespread among a wide variety of animals, scientists were surprised this year when they suddenly detected infections in the udders and milk of cows, particularly dairy cows. It's not uncommon for bacteria to cause udder infections, but the influenza virus?

“Typically, we think of influenza as a respiratory illness,” said Dr. Caitlin Sarlo Davila, a researcher at Ames Laboratory.

Much of the research on the disease has been done at the USDA Poultry Research Center in Athens, Georgia, but the emergence of the virus in cattle has prompted the Ames center to join in the research.

Dr Amy Baker, a veterinarian whose award-winning research on swine flu has been working on it, is currently testing a vaccine for cattle and said preliminary results are expected soon.

USDA spokeswoman Shiloh Weir said the research is promising but in the early stages of development. No approved avian flu vaccines are yet used on U.S. poultry farms. Weir said efforts are underway to develop a vaccine for poultry, but any such strategy is difficult and there's no guarantee it will eradicate the virus.

Baker and other researchers are also working on studies to learn how the virus spreads among cattle, in high-containment facilities where scientists and animal handlers wear special respiratory tracts and other protective gear.

In the study, four yearling cows were exposed to a mist containing the virus, then the virus was sprayed onto the teats and udders of two dairy cows. The first four were infected but showed minimal symptoms. The second two became more ill, losing their appetite, producing less milk and producing a thick, yellowish color.

The conclusion that the virus spreads mainly through contact with virus-rich milk, and potentially through shared milking equipment, is consistent with what health investigators have known, but doing the study was important because getting complete information from dairy farms was sometimes difficult, Webby said.

“At best we had some inklings about how the virus was spreading, but we didn't really know,” he added.

USDA scientists are doing additional work to test the blood of calves that drank raw milk for signs of infection.

A study conducted by the University of Iowa center and several universities concluded that the virus had likely been circulating for months before it was officially reported in Texas in March.

The study also identified new and unusual genetic combinations in the avian flu viruses that infected the cattle, and researchers are working to understand whether this could lead to infection or spread between cattle, said study leader Dr Tavis Anderson.

Either way, Ames researchers expect to be busy for years to come.

“Do cows have their own flu? Can it be transmitted from cows to wild birds? Can it be transmitted from cows to humans? Can it be transmitted from cows to pigs? “Anderson added, “Understanding those dynamics is, I think, one of the open research questions, or one of the things.”