H3N2 Canine Influenza: The Southeastern United States Hit by a New Epizootic

Outbreaks of canine influenza A have been detected in several U.S. states, initially in the southeastern part of the country, first affecting Georgia and Florida, before spreading to North and South Carolina, then Kentucky, Missouri, Illinois, and as far as Texas. This is the H3N2 subtype, the same viral strain identified during the epizootic that struck the Chicago area in the spring of 2015. In areas where the influenza virus is spreading, veterinarians and dog owners are urged to remain vigilant for early detection of any signs of respiratory illness and, if necessary, isolate affected animals for at least 21 days, in accordance with the protocol implemented two years ago to limit the spread of the disease.   Canine influenza, which is highly contagious, spreads easily among dogs in close contact and, in rare cases, can infect cats. While approximately 20 to 25 percent of infected dogs remain asymptomatic, they can still engage in shedding and spread the virus to other dogs. At the same time, 80% of dogs exposed to the virus develop clinical signs of the disease within 24 to 48 hours and can engage in shedding of the virus for up to 28 days after exposure. Furthermore, the influenza virus can survive for up to 48 hours on hard surfaces, 24 hours on clothing, and 12 hours on hands. During the 2015 epizootic, a retrospective study* examined the persistence of the canine influenza A H3N2 virus to estimate the appropriate isolation period for infected dogs based on the duration of viral shedding. The results show that dogs infected with the influenza virus must be isolated for a minimum of 21 days after the onset of the disease. Even if clinical signs disappear earlier, viral shedding may persist. Thus, in 2015, the spread of the H3N2 virus was significantly slowed when shelters and other kennels implemented this isolation protocol of at least 21 days. However, isolation is only one part of controlling influenza A. Vaccination also plays a role in reducing the incidence and severity of the disease. In areas where influenza viruses are active, animal owners are advised to avoid places where dogs gather and to prevent contact between animals. They should contact their veterinarian at the first sign of symptoms (coughing, lethargy, loss of appetite, nasal discharge, increased respiratory rate, fever). The American Kennel Club (AKC) has issued a statement** intended to inform owners, breeders, exhibitors, and others about what to do if an infection is suspected. The goal is to minimize risks and reduce the spread of the disease. To this end, owners of dogs at risk of exposure to the canine influenza virus are encouraged to have them vaccinated at least once a year against the two strains—H3N8 and H3N2—that are circulating in the United States . Two veterinary vaccines, including a bivalent one, are currently available. However, there is no vaccine for cats at this time. Fortunately, soap and water are very effective at inactivating influenza viruses. According to the American Veterinary Medical Association (AVMA), they are easily killed by common disinfection agents used in veterinary clinics, animal shelters, and other such settings. However, it is essential to strictly follow isolation protocols and to clean and perform disinfection on clothing, equipment, surfaces, and hands after any exposure.   * http://avmajournals.avma.org/doi/abs/10.2460/javma.248.9.1022 ** http://www.akc.org/content/news/articles/canine-influenza-virus-notice/