Overview
Cats can be infected by a tiny red blood cell parasite that was formerly called Hemobartonella felis. This disease, which results from a bacterial infection, is referred to as feline infectious anemia. The infectious agents responsible for the disease have been renamed C. Mycoplasma haemominutum (CMhm) for the small sized strain and Mycoplasma haemofelis for the large sized strains. It is important to make this distinction because these two subtypes of the blood parasite produce quite different clinical signs.
The CMhm strain can sometimes cause a mild to moderate hemolytic anemia. The term "hemolytic" refers to the “lysis” or destruction of red blood cells. This results in anemia. However, The small form usually causes no illness.
The haemofelis strains cause a severe anemia. Fevers and weight loss, poor appetite, pale mucous membranes and lethargy are signs that are commonly noted.
Causes of Feline Infectious Anemia
The routes of transmission of Mycoplasma infections between cats are not fully understood, but it is known that blood transfusions can transfer this bacterial parasite, and queens have been known to infect their kittens. Cat to cat bite wounds may also serve as a route of transmission. Finally, the most likely route of infection is through fleas. Indeed, fleas may act as vectors, biting first an infected cat, and subsequently spreading the parasite when another cat is bitten.
A veterinarian can sometimes see the parasites in blood smears viewed under the microscope. The parasites attach to the outside of the red blood cell wall. A test to identify parasite DNA can be performed as well. This PCR-DNA test may be necessary for a diagnosis because parasites are not always found in the blood stream. This cyclic presence of parasites may also lead your veterinarian to suggest serial blood samples from different days be sampled.
Treatment
The more pathogenic parasite strain can produce death rates of up to one in every three untreated sick cats, so prompt treatment is important. Cats with chronic viral infections such as feline leukemia virus and feline immunodeficiency virus will usually be more severely affected, and co-infection with these viruses is unfortunately common in hemobartonellosis cats.
Antibiotics, anti-inflammatory therapy, and perhaps intravenous fluids and blood transfusions may be required. Therapy does not completely clear the parasite so the cat will continue to carry the parasite, but relapse is uncommon.
With prompt, aggressive treatment, the prognosis is fair.