New perspectives about Hemotrophic mycoplasma (formerly, Haemobartonella and Eperythrozoon species) infections in dogs and cats

Based on molecular data, the species formerly known as Haemobartonella and Eperythrozoon have been reclassified as Mycoplasmas. These hemotrophic mycoplasmas are red cell parasites that cause acute and chronic disease in cats and dogs and have a worldwide distribution. It was recently recognized that two different species of hernotropic parasites, Mycoplasma haemofelis (Ohio or large form) and Mycoplasma haemominutum (California or small form) can infect the cat and there are differences in their pathogenicity. Acute infection with M haemofelis is associated with a massive parasitemia of red cells that leads to severe and sometimes fatal hemolytic anemia. On the other hand, cats infected with M haemominutum developed only minimal clinical signs of acute disease and negligible anemia. These parasites are also notorious for their ability to evade the host's immune response and successfully establish chronic infection. They are recognized as a secondary pathogen in conjunction to retroviruses, including Feline Leukemia Virus (FeLV) and Feline Immunodeficiency Virus (FIV) and may promote neoplastic transformation of hernatopoietic cells in these cats. Recent studies based on polymerase chain reaction testing (PCR) have shown that as high as 28% of all cats that are anemic have a hemotrophic mycoplasma infection. In the dog, the infection is usually subclinical and often unrecognized until the dog's spleen is removed. The parasite, M haemocanis, has been found in a number of kennel-raised dogs and has the potential to adversely affect or confound research results. It is important to remember that despite an intense immune response and/or antibiotic treatment, cats and dogs that are infected with this parasite are likely to remain chronic carriers. The possible sequelae of chronic infection have not been defined.