MIAMI (AP) _ The second discovery in a month of an exotic parakeet infected with Newcastle's disease has prompted the destruction of 2,000 imported birds to protect Florida's $250 million poultry industry, officials said.

The U.S. Department of Agriculture said a quarantine is in effect for wholesalers and dealers who bought birds from the supplier of the gray cheek parakeet found dead Tuesday.

Another gray cheek parakeet that came through the Miami warehouse was also found to be infected.

Among the 2,000 birds that came through the same warehouse as the two diseased ones and will be put to sleep with carbon dioxide are parrots, parakeets, macaws, cockatiels, cockatoos and conures, officials said.

Newcastle's disease, first noted in Newcastle, England, can affect all birds and causes respiratory and gastrointestinal problems.

According to Dorland's Illustrated Medical Dictionary, Newcastle's Disease is transmissible to humans by contact with infected birds.

''Our main concern is the poultry industry,'' said Dr. Dean Philson, a USDA veterinarian from Tampa. ''Poultry is extremely susceptible to the disease. It kills them like flies.''

Federal veterinarians are examining fowl at 26 other Florida locations for other potential contamination.

''We don't consider it a panic situation,'' said Dr. Dale Bruch of the USDA. ''We're only talking about 2,000 birds. When you consider 165,000 came through Miami last year, we're not talking in very big terms. We feel we've got a handle on it.''

The infected parakeets, worth an estimated $125 to $150 each, apparently were shipped to Miami in October from Peru, according to Philson.

''The birds had been sold by this importer to another wholesaler that had sold the birds in Tampa,'' said Philson, adding there were no indications the disease may be linked to smuggled birds.

The animals will be put in plastic garbage bags which will have cold carbon dioxide forced inside, a process ''very similar to going to sleep,'' Philson said.

''The brain is deprived of oxygen and the bird just goes to sleep. It's the most humane way we know of euthanizing an animal.''

The cost of destroying the birds will be absorbed by the USDA because the animals had passed through a 30-day quarantine, officials said.

In 1980, during the last major outbreak of Newcastle's disease in South Florida, a wholesale importer in Miami was forced to destroy 6,000 birds.

California lost 12 million birds, in damage estimated at $56 million, during a 1971 poultry outbreak.

''We have these little outbreaks from time to time,'' Philson said. ''Most of them cause no problems. The troubles occur when it gets in the chain of commerce.''