Investigating the H1N1 threat

Ames, Iowa — While the first known cat tested positive for the H1N1 influenza virus, veterinary immunologists say more research is needed to understand the risks of cat-to-cat transmission.

ISU veterinarians: Brett Sponseller (left) and Albert E. Jergens were credited with detecting the first case of H1N1 in a cat.

Dr. Albert E. Jergens, DVM, PhD, Dipl. ACVIM, a professor in the Department of Veterinary Clinical Sciences at Iowa State University (ISU) College of Veterinary Medicine, and Dr. Brett A. Sponseller, DVM, PhD, Dipl. ACVIM, assistant professor in the departments of Veterinary Clinical Sciences, Veterinary Microbiology and Preventative Medicine, don't know much about how the virus was transmitted to the 13-year-old cat they treated, but a hunch was later confirmed as the cat tested positive for H1N1. To date, the virus has been confirmed in five ferrets, swine herds in the United States and Canada, and a flock of Canadian turkeys.

"We detected viral nucleic acid that was positive for H1N1," Sponseller explains of the first cat case. "In addition, the virus was cultured in embryonated chicken eggs by the National Veterinary Services Laboratory of the United States Department of Agriculture."

So, what's left to learn about this virus?

On a hunch: Sponseller and Jergens tested a cat for H1N1 on a hunch. Now they want to investigate further to see what this case means for other domestic species.

"We would like to do challenge studies in cats to establish relative susceptibility in cats; study horizontal transfer and see about other pets." If funded the research team also would like to study seroepidemiology in both the cats and their owners.

The infected cat was brought to Sponseller initially by an employee of the veterinary college. The indoor cat presented with lethargy and wheezing. After a routine respiratory workup showed infection in the back of the lung field, Sponseller began to suspect H1N1. His suspicion was strengthened because the owner was sick with flu-like symptoms.

"I don't know that anyone would say that from all that we expected it to be influenza, but it certainly was on the list," he says. "This cat did not exhibit what we would consider typical signs of upper respiratory disease. It is a lower respiratory disease."

Since ISU could test for H1N1, it was an easy to initiate, Sponseller says.

"It doesn't mean that just because the cat had respiratory disease and the humans did that it was the same thing," Sponseller says. "But for us it seemed pretty plausible, at least in retrospect, that it came from humans."

The cat was treated with supportive care and recovered, but the international media coverage the case generated at Iowa State is still being felt. Sponseller returned home that night to a slew of media inquiries requesting interviews on his home phone. The tabloid-style television show, "Inside Edition," even called the school trying to get an interview with the cat's owners. They have remained anonymous.

"Practitioners should view this like state health departments. Initially, try and pursue a diagnosis so the veterinary community has an idea of prevalence and transmission from humans to cats," Sponseller says. "Manage it on a case-by-case basis and determine if the client is willing to pay for testing," he adds.

Dr. Ann Garvey, Iowa's state public health veterinarian, says influenza has been found in cats before, and owners should use common sense when it comes to taking their cats to the veterinarian.

"There were cases of illness in cats, where they found the strain did not pass naturally from cat-to-cat and there was no evidence it was passed from cat to human," Garvey says. "We're trying to emphasize people to take the same common- sense precautions with pets as they do with other people."

Dr. Ronald Schultz, an immunologist at the University of Wisconsin's veterinary school, says the case poses interesting questions for virologists. The possible next steps will be to determine whether or not the cat can serve as a source of virus, and whether or not it is capable of infecting other cats.