Leucocytozoon is an apicomplexan avian blood parasite transmitted by black flies in the family Simulidae.1 It is known to cause significant mortality in domestic poultry and waterfowl as well as epizootics in the wild.2
Leucocytozoon gametocytes were detected in the peripheral blood smear of a white-winged scoter (Melanitta fusca deglandi) admitted for rehabilitation with multiple, deep lacerations and anemia. The bird was stabilized and skin wounds debrided and closed surgically, but she developed pododermatitis and keel ulcerations and anemia worsened. Treatment for Leucocytozoon began 4 weeks after admission using a previously published combination of pyrimethamine, folic acid and a trimethoprim/sulfa.3 Pyrimethamine was prepared by a commercial compounding pharmacy and administered orally in food (0.05 mg/kg BID) for 30 days. Because pyrimethamine is a folic acid inhibitor, folic acid was supplemented orally (1 to 8 mg BID) at gradually increasing doses for 33 days. Sulfonamides act synergistically with pyrimethamine, so oral trimethoprim/sulfamethoxazole (30 mg/kg BID) was given for the first 7 days of antiprotozoal treatment. The bird tolerated these medications well with no adverse reactions. Blood smears were examined during and for 6 months after treatment. Anemia resolved and the number of Leucocytozoon steadily decreased. No gametocytes have been seen in blood samples since 4 weeks post-treatment. The bird has remained in captivity due to abnormal molt but is otherwise healthy. The anti-protozoal treatment described appears to have been safe and effective in eliminating circulating Leucocytozoon and resolving the associated anemia; however, additional trials are needed to confirm the apparent efficacy seen in this individual.
The authors thank the Alaska SeaLife Center Husbandry staff and Stranding Program for their observations and excellent care of this duck. The bird was collected under USFWS Rehabilitation Permit No. MB834075-0.
* Presenting author
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2. Herman CM, Barrow JH Jr, Tarshis IB. Leucocytozoonosis in Canada geese at the Seney National Wildlife Refuge. J Wildl Dis. 1975;11(3):404–411.
3. Greiner E, Ritchie BW. Parasites. In: Ritchie BW, Harrison GJ, Harrison LR, eds. Avian Medicine Principles and Application. Lake Worth, FL: Wingers Publishing Inc.; 1994: 468, 473, 1020.