Synonyms: Balfouria gallinarum, Balfouria anserina.
Disease: Aegyptianellosis, avian piroplasmosis.
Hosts: Chicken, goose, duck, turkey. This species has been transmitted experimentally to the turtle dove, ringdove, crowned crane, quail, pigeon, canary and other birds (Curasson, 1943). The chicken is probably the most important host.
Geographic Distribution: North Africa, South Africa, Indochina, India, USSR (Transcaucasia), southeast Europe.
Morphology: The trophozoites are usually small, ranging in size from 0.5 to 3 or even 4 u, depending upon the stage of development. They are round, oval or piriform, sometimes with a vacuole. They multiply by schizogony, producing a variable number - up to 20 - of very small merozoites.
Life Cycle: The natural vector is the fowl tick, Argas persicus. Transmission does not take place either thru the egg or stage-to-stage. After the adult tick becomes infected by feeding on an infected bird, it takes 26 days or more before it is able to transmit it to another bird (Bedford and Coles, 1933). Ticks can remain infective for as long as 162 days. The stages of development in the tick have not been described. A. pullorum can be transmitted experimentally by intravenous, intraperitoneal, subcutaneous or intramuscular injection or by scarification. The incubation period in chickens is 10 to 15 or more days.
Pathogenesis: A. pullorum may cause either a latent, chronic, subacute or acute disease in chickens. The acute form occurs primarily in young or imported birds in endemic regions, while the chronic and latent forms occur primarily in adult birds in endemic regions. Severe outbreaks have been reported in chickens in Algeria, Egypt, South Africa and Greece. Ducks and geese are apparently less seriously affected.
The principal signs are anemia, fever, icterus, diarrhea and anorexia. Necropsy findings include splenomegaly, liver degeneration, characteristic greyish yellow kidneys, intestinal congestion, petechial hemorrhages on the serosa, and sometimes pericarditis. Adult birds usually recover.
Immunity: Birds which have recovered from infection are premunized, but their latent infections can be reactivated by splenectomy or by intercurrent disease.
Diagnosis: A. pullorum infections can be diagnosed by identifying the parasites in stained blood smears. They are difficult to stain, however, so the staining time must be prolonged. Affected birds are often simultaneously infected with Borrelia anserina, the cause of fowl spirochetosis, which is also transmitted by Argas persicus.
Treatment: Trypan blue and acriflavine are ineffective against A. pullorum, and variable results have been obtained with stovarsol and quinacrine. Ichthargan is said to be highly effective, but must be given intravenously.
Prevention and Control: These depend upon elimination of the tick vectors.