Aegyptianellosis is an acute, tickborne, febrile disease caused by Aegyptianella spp, a rickettsia in the family Anaplasma-taceae. Infection of avian species, including chickens, turkeys, guineafowl, quail, pigeons, crows, waterfowl, ratites, falcons, passerines, and psittacines has been described. A pullorum is pathogenic in chickens. Ticks, especially Argas spp, transmit the organism; infection can also be reproduced by blood inoculation. Organisms appear as single or multiple, round, “signet-ring” (0.5–4 μm) or irregular oval bodies in RBC often lateral to the nucleus. They must be differentiated from trophozoites of Plasmodium and gametocytes of Haemoproteus. Infections are most common in tropical and subtropical areas of Africa, Asia, and Europe; infection of wild turkeys in Texas has also been reported.

In endemic areas, infection is mild or asymptomatic. Ruffled feathers, anorexia, droopiness, diarrhea, fever, and high mortality in younger birds can occur in introduced or otherwise susceptible birds. Anemia, which can lead to right-sided heart failure and ascites, enlargement of the liver and spleen, enlarged discolored kidneys, and pinpoint serosal hemorrhages can be seen. Infestation with larval argasid ticks and Borrelia infection (see Avian Spirochetosis) may accompany the disease.

Tetracyclines, especially doxycycline, are effective in controlling the disease and eliminating the organism from chronically infected birds. Tick control is an important adjunct to treatment.

Last full review/revision March 2012 by Arnaud J. Van Wettere, DVM, MS, DACVP