The chemosis and conjunctivitis with periorbital swelling and epiphora are characteristic signs of a condition in caged birds which has been seen for many years but in which no infective organism has generally been isolated by conventional methods of bacteriological culture. The condition responds to tetracycline therapy and more recently has been shown in many cases to be caused by Mycoplasma gallisepticum. In the United States a pandemic of the condition is occurring as investigated by several groups of veterinary ophthalmologists (Kollias et al Experimental infection of house finches with Mycoplasma gallisepticum.
J Wildl Dis. 2004 40(1):79-86, Farmer et al, Mycoplasmal conjunctivitis in songbirds from New York, J Wildl Dis. 2000 36(2):257-64. Donht et al, Epidemic mycoplasmal conjunctivitis in house finches from eastern North America.
J Wildl Dis. 1998 34(2):265-80, Fisher et al, Mycoplasmal conjunctivitis in wild songbirds: the spread of a new contagious disease in a mobile host population.
Emerg Infect Dis. 1997 3(1):69-72)). In many of these birds systemic infection is fatal but in caged birds tetracycline therapy is curative.