The Department of Natural Resources of the State of Minnesota has confirmed isolation of H5N1 from an immature fox in Anoka County.  This is the first confirmed isolation of H5N1 from a mammal in the State.  The case follows reports of isolations of H5N1 in Ontario, Canada and also cases of infected foxes in the EU.

It will be important to establish the molecular relationship between the isolate from this mammalian species and from cases of avian influenza in either commercial or backyard flocks in the county.  The second question is the duration of shedding by foxes or other species that may yield the virus. It is presumed that specific mammalian species will shed virus for a limited period and hopefully will not become a reservoir host.  Depending on clinical involvement, susceptible mammals may serve to transmit virus among farms in a limited area thereby complicating biosecurity.  From the initial report it would appear that kits are clinically affected, and their survival and capacity to transmit virus would be limited under practical conditions.

The Minnesota Veterinary Diagnostic Laboratory as with other state facilities will commence screening foxes, skunks, raccoons and rodents for H5N1 and possibly other avian influenza viruses as a routine procedure and also initiate field surveillance of these species.