H1N1 Can Be Transmitted From Humans to Pets

July 20, 2010 (Atlanta, Georgia) — Cases of H1N1 in cats and ferrets appear to have been transmitted from symptomatic human household members, according to a new analysis from the Oregon Department of Human Services.
Emilio E. DeBess, DVM, from the Oregon Department of Human Services, in Portland, presented the findings here at a poster session at the International Conference on Emerging Infectious Diseases 2010.
"We are reporting the first cluster of laboratory-confirmed cases of H1N1 in the US," the authors note, "in 4 ferrets and 2 cats."
According to Dr. DeBess, the cases represent the first description of the pathology and viral antigen distribution of lethal respiratory disease in domestic cats after natural pandemic (H1N1) 2009 influenza virus infection, which was probably transmitted from humans.
"Pets can be affected by H1N1 by the same means as humans; therefore, patients with H1N1 should also wash their hands and cover their cough to protect their pets," he told Medscape Medical News.
A total of 4 ferrets were infected, presenting with sneezing, coughing, lethargy and nasal discharge. Three of the ferrets had elevated temperatures. In addition, 2 cats affected with H1N1 presented with severe respiratory distress, dyspnea, and cyanosis but did not have an increased temperature. The 2 cats, one a 10-year-old neutered domestic shorthair and the other an 8-year-old spayed domestic shorthair, died shortly after developing severe respiratory disease.
The samples were found to be positive for H1N1 by both the matrix and N1 real-time reverse transcriptase polymer chain reaction assays for the 2009 H1N1 pandemic influenza virus and were subsequently confirmed by the US Department of Agriculture/Animal and Plant Health Inspection Service/Veterinary Services/National Veterinary Services Laboratories.
Marked consolidation of the lung lobes and air bronchograms throughout the chest were observed on x-ray of the cats, and pleural effusion was identified in one. Both cats also exhibited pneumonia and fibrin exudation in bronchioles and alveoli.
According to Dr. DeBess, transmission of H1N1 to pets is the same as it is for humans, but it is unknown at this point whether H1N1 could spread back from pets to humans, although "it could only make sense," he said.
Brett Sponseller, DVM, PhD, assistant professor of vet microbiology and preventive medicine at Iowa State University, in Ames, and colleagues recently reported a similar single case of suspected human-to-cat transmission earlier this year. He commented that the frequency of cross-species transmission to companion animals is unknown at this point. "However, I suspect that it is uncommon, yet underdiagnosed," he told Medscape Medical News. "As in humans, most cases in animals appear to be self-limiting and may go undiagnosed," he added.
According to Dr. Sponseller, with the advent of H1N1, "medical professionals need to be aware of the (reverse) zoonotic potential of this virus and recommend safety precautions to minimize spread to and from companion animals." Recommendations are outlined on the American Veterinary Medical Association Web site.
The authors and commentators have disclosed no relevant financial relationships.
International Conference on Emerging Infectious Diseases (ICEID) 2010: Poster Session. Presented July 13, 2010.