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Aquatic Animal Health team contributes to dolphin die-off finding

Drs. Mike Walsh, James Wellehan and Tom Waltzek. (Photo by Patrick Thompson)

Veterinarians within UF’s Aquatic Animal Health program played a role in the key finding, announced Aug. 27 by the National Oceanic and Atmospheric Administration that the cause of a massive die-off of bottlenose dolphins in the mid-Atlantic region this year is due to a measles-like virus known as dolphin morbillivirus.

Drs. Thomas Waltzek and Jim Wellehan are co-directors of UF’s Wildlife and Aquatic Animal Veterinary Disease Laboratory (WAVDL), which is housed within the Aquatic Pathobiology Laboratory as part of the university’s Emerging Pathogens Institute. Waltzek and Wellehan were asked to participate in a dolphin morbillivirus epidemiology task force formed earlier this year, a few months before NOAA declared the die-off an unusual mortality event (UME) on Aug. 8.

“We were invited on the basis of our expertise,” said Waltzek, an assistant professor in the college’s Department of Infectious Diseases and Pathology. He said UF is one of the few groups involved with all four NOAA-declared UMEs going on right now. Well respected for its solid researchers, UF’s Aquatic Animal Health program is also funded in part through a NOAA-Prescott grant to study respiratory viruses in marine mammals.

Waltzek said he and Wellehan were intrigued by the recent outbreak as one of their colleagues, Dr. Mike Walsh, co-director of the Aquatic Animal Health program, and Dr. Stephen Cassle, an AAHP resident, had diagnosed morbillivirus in a single stranded bottlenose dolphin found in 2012 in the Gulf of Mexico.

“In that case, a wild geriatric individual stranded on the beach and died shortly thereafter,” Walsh said.

“In the Gulf, and even more so in the Atlantic, there had not been a morbillivirus finding in a really long time,” added Waltzek.

The current mid-Atlantic die-off is known to have affected at least 500 bottlenose dolphins, but the researchers said many affected dolphins aren’t even found.

Reported strandings are more than nine times the historical average for the months of July and August for the mid-Atlantic region, with all age classes of bottlenose dolphins involved. Strandings have ranged from a few live animals to mostly dead animals, with very many decomposed, according to information provided by NOAA.

UF’s role, including Waltzek and Wellehan’s involvement  on the task force, consisted of polymerase chain reaction (PCR) testing for the virus in approximately 100 tissue samples collected from dolphins affected in the mid-Atlantic die-off. This testing was completed by Dr. Natalie Steckler, a postdoctoral researcher with the AAHP, and Linda Archer, who manages WAVDL.

“Moving forward, we will be working toward characterizing the genomes of dolphin morbillivirus strains to better understand the epidemiology and lethal nature of this disease,” Wellehan said.