All summer, marine biologists and dolphin fans have been paying attention to the high number of dolphin washing up on shore on the east coast. Dead or dying, it was unclear what exactly was killing the mammals. Now, scientists are looking closely at a measle-like virus that is the most likely culprit.
NOAA announced that cetacean morbillivirus is being considered the main factor but that other contributing factors including "other pathogens, biotoxins, range expansion, etc" are not ruled out entirely.
Oceana reports of the virus that it is, "in the same family as human measles and canine distemper. Both whales and dolphins are susceptible to different variations of the virus, which are collectively called cetacean morbillivirus. The disease is usually spread within a species through inhalation of respiratory particles or by direct contact between animals. Sick dolphins develop pneumonia, skin lesions, and brain infections, eventually washing ashore dead or dying. Morbillivirus is not always fatal—some individuals fight off the disease and produce antibodies that protect them from subsequent infections."
In a usual year, around 150 dolphins are reported washed up, but this year has already seen over 600 dolphins washed up, with many of them washing up since mid-July. NOAA reports that the number is "over nine times the historical average for the months of July and August for the Mid-Atlantic Region."