In response to the outbreak of psittacosis or parrot fever in a number of cockatiels, PetSmart Inc. self-imposed a 30-day quarantine in 775 of its 1,000 stores in 46 states.

Random testing of birds at PetSmart led to the discovery of the disease, which is characterized by coldlike and flulike symptoms. The disease can be passed on to humans, but the infection can be treated with an antibiotic.

The pet store chain stopped selling birds starting Dec. 19 and sent letters to customers who bought birds after Oct. 3 informing them of the parrot fever outbreak and asking them to send their pets to a veterinarian if their birds showed symptoms of the disease.