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H7N2 Influenza in Shelter Cats in New York City

As veterinarians, we know there is truth in the saying that prevention is the best medicine. As shelter veterinarians, we also realize that we will never be able to completely prevent infectious disease from arriving at our doorsteps. But how we recognize and respond once confronted with infectious disease in a population determines our success.

In late November 2016, a geriatric cat named Mimi from the Animal Care Centers of New York City (NYACC) developed pneumonia and respiratory disease testing was performed though Idexx, including Influenza PCR.  When the influenza results came back positive NYACC reached out for assistance to Dr. Sandra Newbury, the Director of the Shelter Medicine Program at the University of Wisconsin-Madison School of Veterinary Medicine (UW-SMP), because of her recent work with influenza in dogs and cats in the Midwest. 

Cats infected with influenza were observed to have non-specific signs of upper respiratory infection such as lethargy, nasal congestion and discharge. A smaller number of cats developed signs of lower respiratory disease including pneumonia.  Concurrent infections with other common respiratory pathogens that cause signs of respiratory disease including calici and herpes viruses were also detected. 

Dogs and cats at the NYACC shelters were tested for influenza virus by PCR through Wisconsin Veterinary Diagnostic Laboratory (WVDL).  While a wave of infection was seen to be moving rapidly though the feline population, the fact that no dogs tested positive for influenza made it unlikely that this was caused by canine influenza virus as occurred with H3N2 canine influenza virus in 9 cats in an Indiana shelter in 2016. No other species in the shelters tested positive for influenza.

The WVDL performed further testing to identify the virus as H7N2 low-pathogenic avian influenza, which was confirmed by USDA National Veterinary Services Laboratory. This is the first time this virus has been detected and transmitted among cats.  This particular strain of the virus was present in live bird markets in the early 2000’s but had been thought to be eradicated since 2006. The original source of the infection is still unknown.

A collaboration among numerous agencies including UW-SMP, NYACC, United States Department of Agriculture, NY State Veterinarian, NYC Health Department and others, came together to develop a plan for response. Many factors were taken into consideration including the risk to agriculture and human health, as well as the desire to stop the introduction of a new pathogen into the feline population in the region and beyond. Canine influenza was not able to be contained after the initial outbreaks in 2004 and 2015 and the hope was to be able to stop the spread outside the shelter as had been done on a much smaller scale in Indiana. Thanks to Dr. Newbury’s involvement and the generosity of Maddie’s Fund, a quarantine for infected and exposed cats was proposed to avoid depopulation of the nearly 500 cats at NYACC’s 3 shelters. 

Initial steps included contacting adopters and rescue groups who had acquired cats from the affected shelters. Diagnostic testing through WVDL was offered for all cats recently adopted and transferred thanks to funding from Maddie’s Fund. More than 350 humans were screened for H7N2 by NYC Health Department and only one person, a veterinarian involved in performing diagnostic sampling, tested positive. That veterinarian’s symptoms were mild and testing the following day was negative. Historically, only two other people in the US have tested positive for the H7N2 virus and both recovered fully. Because of these factors, public health officials concluded that the risk of human infections from cats was low and recommendations regarding appropriate personal protective equipment were made to avoid any new infections.
 
Assistance from the ASPCA was requested to set up and operate a quarantine facility. The ASPCA’s Field Investigation and Response team rapidly mobilized to set up a temporary shelter in a warehouse in Long Island City and within two weeks 464 cats and kittens were transported to the quarantine facility. Cats were housed primarily in group housing and individual housing was available as needed. Cold, warm and hot zones were implemented to contain the virus to cat housing areas only. 

Sampling of cats by staff from UW-SMP, Tufts, and University of Missouri was continued through February to determine when cats could be declared influenza-free and released for adoption and transfer to rescue.  Antibody testing performed by Cornell Animal Health Diagnostic Center also assisted in determining cat’s recovery from infection. The last cat to test positive was on February 5 and all cats were released from quarantine by early March 2017 and have been placed with adopters and placement partners.  In total over 500 cats were housed in the quarantine facility, cared for by more than 300 staff and volunteers of the ASPCA Field Investigations and Response team contributing over 12,000 hours to the effort. We are most pleased to report that as of this time there have been no positive tests since February 5, 2017 and no cases reported that were not connected to the shelters originally involved in the outbreak. This would not have been possible without the cooperation between each of the various agencies and organizations involved.

It is prudent to reflect on these situations and identify if there are any factors that contributed to the outbreak and ways to prevent it in the future.  Defining capacity for care and avoiding conditions that lead to crowding is critical to preventing the spread of infectious disease in a population. Double compartment housing for cats and dogs is also essential and can significantly reduce the spread of pathogens through fomite transmission as well as reduce stress. NYACC took advantage of the situation and converted their single cat housing units to double compartment by installing portals with assistance from Maddie’s Fund and UW-SMP staff and volunteers. They are also working closely with the UW-SMP team to establish and maintain their capacity for care and we are excited by what has been achieved thus far and know they will do great things going forward.