Avian tick paralysis caused by Ixodes brunneus in the southeastern United States.

Between 1988 and 1994, 16 definitive and 26 presumptive cases of tick paralysis were diagnosed in 10 species of birds from five southeastern states in the USA. All birds had engorged adult female Ixodes brunneus ticks on the head region and were partially paralyzed or dead. Cases occurred in the winter and early spring months, and most birds were passerines found in private yards or near feeders. All stages of I. brunneus feed exclusively on birds, and this species previously has been associated with avian tick paralysis. Little is known concerning the life cycle of this ixodid tick and its impact on wild bird populations.