Sarcocystosis, a disease that affects Old World parrots (i.e. those originating from Asia, Africa and Australia), is caused by a protozoan parasite (Sarcocystis falcatula), which is carried by opossums.
Bird food spilled from the cage attracts cockroaches, fruit rats and opossums, which feed around cage areas at night. Roaches, other insects and fruit rats consume contaminated material, such as feces from these opossums. When these roaches or rats then get into a parrot’s food or water dish, into the outdoor aviary or into loose seed bins in pet stores, they defecate, and their stools contaminate the bird’s food or water. This disease is not contagious between parrots, but since groups of birds often are kept in the same area and fed the same food, multiple birds from the same aviary or household are often infected.
In New World species, the Sarcocystis usually forms benign, microscopic cysts in the muscles, and clinical illness in these birds (i.e. conures, Amazons, macaws) seldom occurs. In Old World Species (i.e. cockatoos, eclectus, African greys) the cysts infect the lungs, kidneys and the nervous system. Bleeding from the lungs can cause a severe anemia and death in a short period of time. In birds where the nervous system is affected, uncoordinated movement, weakness and possibly seizures can occur.
Pulmonary (lung) sarcocystosis is most common, and affected birds may show severe labored breathing, weaknessand excessive water consumption. Neurologic signs (weakness, loss of balance) will occur when the nervous system is affected and are seen particularly in cockatoos and African grey parrots.
Diagnosis is difficult because there is no single specific diagnostic test available. A combination of tests may give an indication of infection with sarcocystosis. Affected birds do not shed cysts in their stool; although, if the infection is severe enough that an overwhelming number of cysts are ingested, a few may pass through the digestive tract and be visible in the feces. Anemia is a prevalent sign on blood work in many birds, but other disease processes can also cause anemia. Often the diagnosis is based on clinical signs, anemia, the species of bird affected and location, Florida being one of the primary areas where this disease occurs.
Therapy includes a combination of antiprotozoal drugs and supportive care. Pyrimethamine, a drug used for treating toxoplasmosis and other systemic protozoal infections, is often used in conjunction with trimethoprim-sulfadiazine in an attempt to control the organism. A newer medication used in horses with a similar disease may be useful. Treatment is often needed for a period of weeks to months.