Dolphins in Sarasota Bay, Fl and elsewhere are vulnerable to cetacean morbilliviruses. These are viruses that can cause large scale mortalities, referred to as Unusual Mortality Events.
New research has looked at dolphin “herd” immunity levels along the southeastern coast of the US to identify viral disease risk factors. Blood and tissue samples were analyzed from several locations where dolphin health assessments have been conducted, or where die-offs have occurred.
As you may remember from school, exposure to a virus results in an immune reaction, which creates antibodies. Analysis of the anti-bodies can be used to identify the specific virus that caused the original infection.
In this study, the researchers examined several possible antibodies to identify the one most useful to predict mortality risks for bottlenose dolphins. Their analysis suggested cetacean morbillivirus was the best indicator.
Their findings suggest that bottlenose dolphin populations in Sarasota Bay and Charleston, SC are among the most at risk.
These are relatively isolated resident dolphin communities that are not known to have been exposed to morbilliviruses in recent years. Thus, they are vulnerable to infection if exposed to morbilliviruses.
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The Abstract for the article is included below, and you may download a pdf.
ROWLES, T. K., SCHWACKE , L. S., WELLS , R. S., SALIKI , J. T., HANSEN, L., HOHN, A., TOWNSEND, F., SAYRE, R. A., and HALL, A.J., Evidence of susceptibility to morbillivirus infection in cetaceans from the United States. MARINE MAMMAL SCIENCE, 27(1): 1–19 (January 2011). DOI: 10.1111/j.1748-7692.2010.00393.x This article is a US Government work and is in the public domain in the USA.
Cetacean morbilliviruses (CeMV) are viruses that can cause mass mortalities among various odontocete species. In this study levels of “herd” immunity in cetaceans from the U.S. coast are described from the distribution and prevalence of antibodies against morbilliviruses. Neutralizing antibody titers against dolphin morbillivirus (DMV), porpoise morbillivirus (PMV), phocine distemper (PDV), and canine distemper viruses (CDV) were measured. Positive samples had higher titers against the CeMV than against the other morbilliviruses tested, indicating that although PDV or CDV can be used to investigate exposure their use may result in a higher false negative rate. The results suggest that morbillivirus did not persist in coastal populations of bottlenose dolphins (Tursiops truncatus) after the major outbreaks that occurred in the 1980s and 1990s. Bottlenose dolphins from Beaufort, North Carolina; St. Joseph Bay, Florida; and Cape May, New Jersey had anti-DMV seroprevalences ranging from between 15% and 33% but those from Charleston, South Carolina and Sarasota Bay, Florida, sampled in recent years were largely negative. These latter groups are therefore now vulnerable to infection and could experience high mortality if exposed to CeMV. Sero-surveys of this kind are therefore vital for assessing the risk of new and recurring viral outbreaks in coastal cetaceans.