The deadliest known outbreak of a measles-like virus in bottlenose dolphins has killed a record number of them along the US Atlantic coast since July, officials said.
A total of 753 bottlenose dolphins the animals washed up from New York to Florida from July 1 until November 3, the National Oceanic and Atmospheric Administration said. That is more than 10 times the number of dolphins that would typically turn up dead along east coast beaches, said Teri Rowles, co-ordinator of the NOAA Fisheries Marine Mammal Health and Stranding Response Programme.
"Historic averages for this same time frame, same geographic area is only 74, so you get an idea of the scope," she said.
The death toll is also higher than the more than 740 strandings in the last major Atlantic morbillivirus outbreak in 1987-88. And they have come in a much shorter time period, leading officials to anticipate this event could get much worse.
"It is expected that the confirmed mortalities will be higher," Rowles said. "If this plays out similar to the '87-88 die-off, we are less than halfway through that time frame."
The cause of death is morbillivirus, a form of marine-mammal measles that is similar to canine distemper and can cause pneumonia, suppressed immune function and brain infections that are usually fatal.
There is no evidence that cetacean morbillivirus can cause disease in people.
However, sick dolphins can also have bacterial or fungal infections that do pose risks to people, so beachcombers are advised not to approach stranded animals.