In July, 91 dead or dying animals washed ashore from New York to Virginia, 20 in New Jersey. In the first week of August, an additional 35 animals washed up, 10 in New Jersey.
So far, no "unifying" element has emerged that would indicate a diagnosis, Rowles said, and it may take weeks to find one.
However, one animal tested positive for morbillivirus, which is similar to measles in humans and distemper in dogs.
Morbillivirus is high on the list of suspects - in part because it has been the cause of large epidemics of dolphins across the globe. It was first reported in a 1987-88 die-off of dolphins in the Mid-Atlantic when 742 animals died.
"We're not saying this is a morbillivirus outbreak," Rowles said. "But because of the size of it right now, everbody's making that link at this point."
Susan Barco, senior scientist at the Virginia Aquarium and Marine Science Center in Virginia Beach, worked on the 1987-88 event.
Those animals had "all kinds of lesions," she said, and "apparently died from many different things." Researchers suspected that their immune systems were compromised by the virus and that they were dying from things they could normally resist.
Researchers are seeing some lesions in the recently stranded animals "but no smoking gun," Barco said. "We're seeing a lot of different things."
Rowles said that even if the virus were to emerge as the cause of the deaths, there is no way to inoculate or treat the large population of bottlenose dolphins living off the Mid-Atlantic coast.
Although dolphins and humans share some pathogens, Rowles said, there is no known threat to humans at this point. She emphasized, however, that people who find a dead or dying dolphin should not touch it or let their dogs near it. They should call the stranding hotline, at 1-866-755-6622.
Researchers on a Thursday teleconference about the strandings said that, so far, they were unaware of any connection to Hurricane Sandy, such as whether toxins were released from storm-roiled ocean sediment.
They typically check on whether any "acoustic events" such as sonar testing were occurring nearby, but "for something to be lasting this long would be very unusual," Rowles said.
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