Ferret Flu

Flu season is upon us and some of us have been gifted early with it's harsh reminder this year.  Recently, this respiratory illness spread through our home like wildfire.  Our patient zero, a teenage girl with a runny nose, came home ill and soon the whole house followed suit.  Unfortunately, we always know that when this particular child is sick we all start the personal countdown to a sick-day.  Despite having two boys in the home that require constant reminders to bathe or wash-up, our sweet girl is the one who can spread disease like a plague rat.  Although she has better hygiene than the other two, she carries bad habits that aide in the spread of illness.  Luckily our typical pets don't contract influenza from people however there is one species that could, ferrets.  

In 1933, ferrets were experimentally inoculated with a human influenza virus and true infection verified.  This led to many other experiments that ultimately found ferrets to be ideal models in human respiratory viral research.  It turns out that a ferret's respiratory anatomy, even on a molecular scale, is so similar to humans that they are capable of contracting and spreading human influenza.  When a virus finds it's way into a host, it must be able to bind to a specific surface receptor to enter a cell and replicate.  This is why we don't worry about catching some diseases like "Kennel Cough" from our pets, we just don't have the binding site.  Ferrets contain a high density of linked sialic acid receptors within the upper and lower respiratory tracts to make it possible for them to contract influenza from their sick caretakers.  This back-and-forth jump between species is what we refer to as a "zoonotic disease".

Influenza is transmitted by aerosol droplets, primarily, but it can survive up to 48hrs on surfaces (potentially longer depending on other environmental conditions).  Transmission via surfaces of contaminated objects is termed "fomite transmission" and is my daughter's route of choice.  Her unexplainable need to feed used tissues to the family dog helped aide in the rapid spread of disease.  Although the dogs are not susceptible, it didn't stop them from leaving trails of disease throughout the house for the rest of us to find.  To make matters worse, replicated virus can be contagious about 24hrs prior to symptoms and up to seven days after.  Once inoculated with enough virus, it takes 2 days for influenza to incubate within your cells well enough to start symptomatic disease.  This leaves a very large window of opportunity for ferrets, or anyone else, to contract the disease.

Just like us, symptoms can range from stuffy noses and coughing to fevers and pneumonia.  Secondary infections from irritated viral tissue and age-of-host are usually what determines the extent/severity of symptoms.  Typically, influenza carries a low mortality for ferrets and many can be treated at home with general nursing care and minimal risks.  Although unlikely to be lethal, you will still be dealing with a sick slinky for 1-2 weeks.  These signs are also very similar to a more deadly ferret virus, Distemper, and therefore should be evaluated by your veterinarian to ensure this isn't being masqueraded as Influenza.  Be sure to let your veterinary office know you suspect Influenza so necessary precautions can be taken to prevent infection to your veterinary staff.

Although we will often get anti-viral medications from our doctors for influenza this is not necessary for couch snakes.  Anti-viral treatment is often ineffective and the risks for viral resistance in a zoonotic disease with low-mortality in ferrets make this an unfavorable treatment option in general.  Likewise, preventative vaccination in ferrets is also not recommended.  The rapid changes and wide variety of influenza virus antigens, ineffective immune responses, and a general high-risk for vaccine reactions in ferrets makes the risk-versus-reward unacceptable.  Overall, it is far better to prevent contraction by limiting exposure than by any other means.  If you feel sick, or suspect illness oncoming, isolate yourself from your ferret and have others feed/water them for a week or two.  If you cannot find assistance, wear a mask and gloves when providing for your ferrets.

While we are on the subject of respiratory diseases, let's not disregard the now notorious COVID (SARS-CoV-2).  Ferrets have their own coronavirus that can lead to severe diarrhea or, if mutated, a lethal over-reactive immune response.  This is very different than the COVID we lived through during the pandemic and shouldn't be confused with one another.  At this time, ferrets have been experimentally infected with COVID-19 and shown transmission of infection with other closely housed ferrets.  There has yet to be a documented case of natural infection in ferrets or transmission to humans.  That's not to say it couldn't happen, theoretically, given all other information we have on ferret respiratory anatomy and microbiology.  However, as with influenza, all ferrets from the experimental studies survived infection without treatment and it seems that risks are low.  Recommendations for dealing with your ferret when COVID is in the home remains the same as with influenza.

So back to our story.  Our patient zero received a very lengthy discussion about fomites and general hygiene, as well as how to cover your mouth when coughing.  The discussion was met with a typical eye-rolling death stare one would expect and we are considering this another "work in progress."  However, it did seem that the fear of getting a pet sick was a far better incentive than getting the rest of us ill.  Ferrets 1, parents 0.  Here's hoping next flu season fares better.