More than 3,700 dead birds have been collected from Virginia shores the past three days by rescue workers attempting to stem a spread of avian cholera on the Chesapeake Bay.

Workers who have been incinerating the carcasses of the birds - mostly old squaws, a type of sea duck - say thousands more are dying of the disease. Dead birds have been found from the mouth of the Rappahannock River to Virginia Beach and across to the Eastern Shore. In Maryland, hundreds of carcasses have been found in Herring Bay and along the Calvert County shore line.

Vern Stotts of the Maryland Department of Natural Resources said the kill apparently began before Feb. 27. That's when Virginians cleaning up oil from a spill near Reedville first noticed clean, uninjured ducks lying dead in the water.

The cholera apparently has no relation to the spill. The disease is caused by a bacteria and is almost always fatal. Scientists believe it is transmitted by nasal discharge and feces; it already has spread to some gulls, black-birds, scaup, grebes and, in Maryland, two Canada geese and a whistling swan.

Charlie Gilchrist, biology supervisor for the Virginia Game Commission, said a chief concern is in cleaning up the carcasses so the disease doesn't spread to commercial chicken farms. "Any feathered critter can get it," he said. The disease poses no other direct threat to man.

There was an outbreak of avian cholera among sea ducks on the Bay in 1970 which claimed 80,000 birds. Stotts said the current outbreak could match 1970, though predictions are only that deaths will be "in the thousands."

He said scientists are not deeply concerned about long-lasting effects on old squaw populations. "They're in relatively good shape," he said. "This may affect populations for a few years but they should bounce back."

They are, however, worried that the old squaws could infect concentrations of canvasbacks and scaup on Maryland's western shore. Practically all the ducks on the Bay are migrating north, and the disease is migrating with them.

"Whether it will spread overland on the flight lines is a good question," said Stotts. "In the past it hasn't."