Mycoplasma haemofelis

Mycoplasma haemofelis is an epierythrocytic parasitic bacterium. It often appears in bloodsmears as small (0.6 μm) coccoid bodies, sometimes forming short chains of three to eight organisms. It is usually the causative agent of feline infectious anemia (FIA) in Canada and the United States.

The ~1.15 Mb genome contains a minimalistic assortment of genes limited to the most basic cellular functions. This leaves M. haemofelis inextricably dependent upon its host for the provision of amino acids, cholesterol, vitamins and fatty acids. The complex and specific conditions that the bacterium requires have made it impossible to culture outside a host thus far.

Arthropod vectors are thought to be the primary source of infection, although M. haemofelis is also known to be transmitted from queen to kitten and following blood transfusion. Immunocompromisation and/or coinfection with FeLV, FIV and other Mycoplasma species can exacerbate symptoms or cause symptoms to arise in previously asymptomatic individuals. Symptoms include anemia, lethargy, fever, and anorexia.

In suspected cases polymerase chain reaction (PCR) tests have become common and commercially available. There is not yet available test that can confirm or deny the presence of infection in the body. Negative PCR doesn't always exclude whenever the cat is infected or not. Furthermore, multiple peripheral blood smears are recommended to perform prior to excluding the disease.

Recent evidence suggests that M. haemofelis may be transmissible to humans.