Dolphins' record viral outbreak sounds alarm

In this 2006 Post and Courier file photo, Dolphins at Breach Inlet are 'mudding,' or strand feeding, which is a behavior unique to Lowcountry bottlenose dolphin, seen along flats and beaches from about Winyah Bay to Savannah.

The virus that's ravaging dolphins along the East Coast isn't anything unusual, by itself. But the record severity of the outbreak is.

Morbillivirus

Measles-like virus affecting whales, dolphins, porpoises.

Weakens lungs and infects the brain, causing abnormal behaviors. Can kill or weaken animal to the point where a secondary infection kills it.

Symptoms include skin sores and pneumonia.

Spread through contact, including with particles from animals' breathing.

NOAA Fisheries

What's more, the virus is causing only one of three unusual bottlenose dolphin die-offs occurring at the same time along the Atlantic and Gulf of Mexico coasts. That is unheard of, and it's the latest toll of an alarm sounding among marine mammal pathologists.

What to do

If you see a stranded dolphin or whale:

Don't approach it or let pets approach it. Don't try to push the animal back into the water.

The morbillivirus isn't contagious, but a weakened dolphin can contract other infections. Stranded dolphins and other marine mammals are often sick, and some diseases can be spread to humans or pets.

Don't wade into the immediate area where a dolphin has just been stranded, particularly if you have an open sore or wound.

Contact the Marine Mammal Stranding Network hotline, 1-800-922-5431.

The animals are considered a sentinel species for detecting threats to ocean - and human - health.

"The morbillivirus virus is going to go through the population and there's going to be increased mortalities," said Gregory Bossert, Georgia Aquarium chief veterinary officer and an adjunct professor at the Medical University of South Carolina. "But we're more concerned about other things we're finding. We're seeing patterns in our oceans that are disturbing."

More than 900 dolphins are estimated to have died of the virus so far along the East Coast - more than a hundred more than the 750 deaths from the previous worst outbreak, from 1987-88.

More than 45 have died off of South Carolina - and the outbreak isn't considered anywhere near over. A second wave of deaths is expected in the spring.

Morbillivirus outbreaks tend to occur from time to time. The virus is always present; exposed survivors develop immunity and following generations lose it. But animals weakened from other stresses are more susceptible to it.

Meanwhile, nearly half of the dolphins in the Indian River lagoon in Florida died this year; the suspected culprit is a toxic algal bloom. And more than 800 dolphins have died so far in the Gulf of Mexico following the massive Deepwater Horizon oil spill in 2010, from a parasitic bacteria and other causes tied to contaminated food.

Bossert is part of a team that has been studying the Indian River deaths. For a control sample, they turned to dolphins in Charleston Harbor and the Stono River. But that "healthy" population isn't so healthy.

Dolphins tested here have shown some of the worst concentrations recorded in the species of flame retardants and other man-made chemicals, and it is weakening their immune systems. They are exposed to so many antibiotics from sewage discharge that they are growing bacteria strong enough to resist antibiotic medications.

"You have to wonder how a dolphin would get an antibiotic resistance; an obvious answer is the discharge," Bossert said. "Contaminants, (ocean) acidification, (rising) sea temperatures, species distribution shifts - when you pull all of them together, they make the perfect recipe of environmental pressures. It does create issues that affect ecosystem health."

Meanwhile, the "sentinel" marine mammals are suffering from new pathogens, or disease causers, and recurrences of old pathogens, at an apparent accelerating rate.

"Human-introduced contaminants ... can also reduce the fitness of bottlenose dolphin populations by stressing their immune system or reducing genetic diversity," the National Oceanic and Atmospheric Administration Fisheries reported in a release on the outbreak. "Morbillivirus outbreaks may also be triggered by a drop in the immunity of bottlenose dolphin populations."

That doesn't bode well for their two-legged fellow species.

"If you look at diseases in humans, the same things are happening," Bossert said. "There's such a great pollution factor."



Reach Bo Petersen at 937-5744, @bopete on twitter or Bo Petersen Reporting on Facebook.

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