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Microfilariae are commonly found in the blood of wild birds but are rare to absent in poultry except in southeast Asia where infections in chickens and waterfowl occur. A high percentage of imported cockatiels have microfilariae. At least 16 genera of filarids are found in avian species. All have an indirect life cycle with bloodsucking insects (eg, lice, mosquitos, midges) serving as intermediate hosts. Adults are relatively
short lived and mature in body cavities, including the eye and ventricles of the brain, respiratory system, cardiovascular system, or connective tissues; some produce characteristic subcutaneous nodules. In contrast, microfilariae are long lived and may be numerous in the skin as well as in the circulation. Increased numbers of microfilariae have been seen in stressed individuals, but they rarely cause clinical disease or mortality. A possible exception is infection of emus with
Chandlerella
, a common filarid of the brain of free-living grackles. Parasites apparently do not produce microfilariae in emus. Affected emus show signs of CNS disease. Treatment with ivermectin, levamisole, or injection of nodules with 0.5% potassium permanganate solution, and surgical removal of adults have been used. |
