AKRON, Ohio -- Owls and hawks began dying in Louisiana in late July.

Then the mysterious avian epidemic jumped to Kentucky and southern Ohio.

Once in Ohio, the disease established a stronghold, killing up to a thousand raptors since mid-August and spreading to other states in all directions.

Now, so many great birds are dying that federal wildlife officials can't keep up with the testing that would prove the suspected culprit is West Nile virus. "It hit the raptors throughout the Midwest like a juggernaut É and we're still counting bodies," said Dr. Pat Redig of the Raptor Center at the University of Minnesota.

No one knows how many of the infected birds die. With treatment, some sick owls and hawks have recovered.

The Sanders Center of Outdoor Education in Perry Township, Ohio, operated by the Stark County Park District, has two great horned owls and five red-tailed hawks in its care, said spokeswoman Christy Morgan.

The birds arrived at the center emaciated, lethargic and suffering seizures, Morgan said. The recovery of one great horned owl required nearly three weeks of care, including hand-feeding rats and frozen chicks to the bird.

The center has released three owls and hawks back into the wild after caring for them, she said, but seven birds have died or been euthanized.

The center's nine resident raptors, which are used in school programs, have not become ill, although their health is a big concern, Morgan said.

For unknown reasons, Ohio appears to have more dead raptors than any other state. The state's Department of Natural Resources believes that 800 to 1,000 owls and hawks have died in Ohio. That's far more than its preliminary estimates of 100 to 150 dead birds.

"It hit Ohio hard," Redig said.

Shortly after Ohio wildlife officials reported large numbers of raptor deaths in mid- to late August, similar reports started to come from Illinois, Indiana, Michigan and southern Ontario.

Later, reports came from Pennsylvania, Iowa, Maryland, Missouri, Nebraska, New Jersey and Wisconsin, said Dr. Emi Saito of the National Wildlife Health Center in Madison, Wis.

Minnesota got hit about Aug. 20, Redig said, and since then, "a steady stream" of sick raptors has been brought to his center in St. Paul.

Normally, the center would be treating 10 to 12 raptors, but it has had 40 in recent days.

"It's something no one anticipated," Redig said. "The West Nile virus has been on the East Coast since 1999."

The sick birds appear to suffer depression, aversion to food and weight loss.