Haemotropic Mycoplasma

So far, Mycoplasma haemocanis and Candidatus Mycoplasma haematoparvum have been described in dogs. Both strains are found in Europe, especially in the Mediterranean area. Clinically, the course of the disease is often just chronic and asymptomatic. In contrast, acute infections with fever, anorexia, weight loss and lethargy are mainly seen in immunocompromised dogs, dogs that had splenectomy or those simultaneously infected with other pathogens. Deaths are also possible. Natural infection probably occurs through vectors, particularly the brown dog tick (Rhipicephalus sanguineus) is being discussed. Vertical transmission through the placenta and milk is also possible, and blood transfusions present a risk of infection as well.

Currently, three different types of haemotropic mycoplasmas with different pathogenicity have been described in cats. In addition to the strain Mycoplasma haemofelis, which is known as Ohio isolate, and the most commonly found California isolate, Candidatus Mycoplasma haemominutum, another strain, Candidatus Mycoplasma turicensis, has been known for some years. The latter was first detected in cats in Switzerland, but seems to occur relatively rarely in Germany.

While Mycoplasma haemofelis can cause serious illness even in immunocompetent animals, an infection with Candidatus Mycoplasma haemominutum usually progresses subclinically in healthy animals. Coinfections are possible with clinical signs typically being more distinct than in monoinfections.

Natural infection probably occurs through vectors; particularly fleas, but also ticks and stinging insects are being discussed. Vertical transmission through the placenta and milk is also possible. Blood transfusions present a risk of infection, too, as well as direct transmission between animals through bite wounds.

Clinical signs in the acute phase are anaemia (haemolytic anaemia as cardinal symptom), fever, splenomegaly, general weakness and possibly polypnoea, tachycardia and icterus. The cause of haemolytic anaemia is damage of the erythrocyte membrane by haemotropic mycoplasmas. Because of the change in the erythrocyte surface, a secondary immune haemolytic anaemia can develop later on; in this case, the direct Coombs test will be positive. The main signs of a chronic infection include weight loss and intermittent fever. Studies have shown that a high percentage of the dog and cat population is infected without the animals showing any clinically relevant signs. These carriers present a particular risk for breeding and blood transfusions.

In its acute phase, an infection with Mycoplasma haemolamae can cause haemolytic anaemia in affected animals. However, infections can also primarily progress silently and lead to a chronic carrier state. The disease may fully break out in these animals in situations linked to stress and/or immunosuppression.

Porcine infectious anaemia (synonym: porcine eperythrozoonosis) is an infectious disease caused by Mycoplasma suis (formerly Eperythrozoon suis). The pathogens attach to the erythrocytes (adhesion, invasion) and provoke damage to and lysis of the erythrocytes due to the formation of autoantibodies. Below the normal body temperature (“cold antibodies”), they agglutinate the blood cells and result in anaemia. Once infected animals go through episodes of anaemia time and again. The disease becomes chronic. Older pigs are only latently infected and only suffer from another relapse when they are very weak. The pathogen remains in the body throughout life.

Mycoplasma ovis is a haemotropic bacterium in small ruminants.

Mycoplasma ovis lacks a cell wall and is a pleomorphic bacterium from the class Mollicutes, which
attaches to the erythrocytes.

Infection with Mycoplasma ovis is a “vector-borne disease”, the vectors are bloodsucking insects such as mosquitoes, lice and autumn flies as well as ticks of the genus Rhipicephalus. Clinical signs include anaemia and weight loss. Anaemia can be so severe that it may lead to cardiovascular failure and death. Signs particularly manifest when there is also an infestation with gastrointestinal parasites.

Both PCR tests (Anaplasma ovis and Mycoplasma ovis) are only available in combination.