People think of fleas as annoying parasites but rarely do we think of them as carrying life threatening diseases.  The plague (Yersinia pestis) is spread by fleas and it can be fatal and in centuries gone by has been fatal to large numbers of people around the world.

The disease that is spread by fleas we see frequently here in cats is called feline infectious anemia.  The name of the infectious agent is Hemobartonella felis or Mycoplasma haemofelis.  It is not contagious to people but it can be fatal to cats.  The parasite attaches to the red blood cell causing the body to think that the red blood cell is a foreign particle.  The spleen in the body then “cleanses” the blood of these invading particles.  This causes an immune mediated anemia.  Jaundice (turning yellow) can occur and the anemia can be so serious as to require a blood transfusion for the cat to survive.

Treatment is successful in most cases if it is caught in time. The antibiotics doxycycline and enrofloxacin both rid the body of this blood parasite and prednisolone is given to stop the immune response of the body killing its own red blood cells. Of course, you have to get rid of the fleas as well by treating the cat and the environment.

I have seen this disease in the same cat a number of times (everytime it gets infested with fleas) and it never gets better without treatment.  So a cat that survives a bout of this disease should always be kept on flea control.  Cats that are feline leukemia positive seem to have a harder time clearing themselves of the parasite.  And there are two types of the parasite (the large form and the small form) and depending on your geographic location, one may be more virulent than the other.

So I know that there are worse things in the world that can happen to your cat but don’t think that fleas can’t kill your cat.  It really can be a serious problem.