Eperythrozoonosis in Llamas and Alpacas

Sharon Heisler, Veterinary Student
David E Anderson, DVM, MS, DACVS
Ohio State University

Eperythrozoonosis is an organism that infects the red blood cells. Their presence may trick the body’s immune system into thinking that these cells are foreign thus causing the immune system to destroy the cells. The destruction of red blood cells may lead to life-threatening anemia.

This organism has recently been renamed Mycoplasma haemolama. The transmission of the organism is via biting insects. Infection with eperythrozoonosis is found worldwide, throughout the year, and in many species, including swine, sheep, cattle, mule deer, elk, and goats. Clinical signs observed are often inappetance, wasting, and occasionally fever. Upon further examination one may notice pale gums, indicating anemia, or even a yellow hue to the skin representing jaundice. Asymptotic carriers, those that are infected but showing no sign of disease, are often a factor in maintenance of the organism within a herd. They go without treatment and therefore are infectious when bitten by an insect and that insect continues to feed off other animals in the herd infecting them in the process.

Eperythrozoonosis does not have to be the primary disease; in fact it is often secondary to other clinical manifestation. The most common association is JLIDS (Juvenile Llama Immunodeficiency Syndrome), severe intestinal parasite burden, and overwhelming stress. These cases have a more severe clinical presentation and may suffer repeated infections. Examination of the blood under a microscope may or may not find the organism on the red blood cell. If present, this observation makes a diagnosis of eperythrozoonosis. Blood work is indicated to evaluate the animal to determine if anemia is present and if a blood transfusion is warranted. There are serologic tests available for eperythrozoonosis, but interpretation is difficult. Recently, Dr. Susan Tournquist at Oregon State University developed a PCR (polymerase chain reaction) test for Mycoplasma haemolama. This test should be more accurate and improve our ability to diagnose this infection and perhaps identify carriers of the disease.

When anemia and clinical disease are associated with M. haemolama infection, treatment consists of tetracycline (20-mg/kg-body weight given daily by injection for 5 days). Be aware that reinfection is possible, especially with asymptotic carries in the herd. Treatment of the whole herd with tetracycline all at once may help prevent a reinfection. However, whole herd treatment success is difficult to quantitate. The new PCR test may be our best tool to accomplish this goal. A more logical approach may be to conduct herd tests and treat only those animals suspected of being carriers - PCR positives. Controlling the biting insects will also play a key role in preventing eperythrozoonosis.

David E Anderson, DVM, MS
Diplomate, American College of Veterinary Surgeons
College of Veterinary Medicine
The Ohio State University