Abstract
A morbillivirus epizootic caused by a newly recognized virus, dolphin morbillivirus (DMV) killed thousands of striped dolphins (Stenella coeruleoalba) in the Mediterranean Sea in 1990-19921. The epidemic vanished in 1994 after causing deaths of common dolphins in the Black Sea. Since then, no incidents suggesting recirculation of DMV in dolphins have been observed in the Mediterranean Sea. A new mortality wave affecting striped dolphins started in July 2007. Initial studies of this recent epidemic2 have shown that DMV is responsible of this event. A rescue program was established to provide support to stranded dolphins along the Catalonian and Valencia Coast. Necropsy was performed in fresh cadavers for investigation of lesions and diseases associated to the epidemic.
A total number of 127 striped dolphins were found stranded in coastal waters of Valencia (n=83) and Catalonia (n= 44) from January to December 2007 (see Figure 1). From them, 13 were found alive, but rescue efforts were unsuccessful, and all dolphins died after a few hours. One dolphin survived for 17 days (negative for DMV at necropsy). Clinical signs observed were disorientation and weakness, and abnormal swimming behaviour. The rest were found stranded at the beach in different conservation states, and only fresh specimens were necropsied. Pathological and virological studied showed pneumonia, lymphoid depletion, and encephalitis as main lesions. DMV-antigen was found in at least half of the dolphins fully necropsied and investigated by immunohistochemistry. Cases of generalized toxoplasmosis and internal mycosis (encephalitis and pneumonia) were also seen.
| Figure 1. | 
Monthly Striped Dolphin Strandings in 2007 at the Valencia and Catalonian Coast |
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References
1. Domingo, M, Ferrer, L, Pumarola, M, Marco, A, Plana, J, Kennedy, S, McAliskey, M, Rima B.K. 1990. Morbillivirus in dolphins. Nature 348: 21
2. Raga, J-A, Banyard, A, Domingo, M, Corteyn, M, Van Bressem, M-F, Fernández M, Aznar FJ, and Barrett. March 2008. Dolphin morbillivirus epizootic resurges in the Mediterranean Sea. Emerging Infectious Diseases, http://www.cdc.gov/eid, Vol. 14, No. 3