December 15, 2011

In the Spotlight - Past Wildlife Disease Investigation from WDA Newsletter

Past Disease Investigation Highlighted in the Wildlife Disease Association Newsletter

Nordic Section Quarterly Report of Wildlife Disease Investigation Cases, July—Sept.

Increased mortality of young harbor seals at Anholt in Denmark

Since the 27th of June increased mortality among young harbor seals has been observed in a colony of approximately 500 adult harbor seals (Phoca vitulina) on the island of Anholt in Denmark [Map It on GeoNames ]. Fifty-six seals were found dead the 27th of June, 61 seals the 28th of June (of which two animals were killed due difficulty breathing and severe emaciation, respectively), 6 seals the 29th of June and nine seals the 1st of July.

Photo of harbor seal courtesy of NOAA
The National Veterinary Institute in Aarhus has so far received 6 harbor seals for necropsy. The seals were found in varying nutritional condition and without significant pathological changes. Several cadavers were characterized by progressive decomposition and only the two animals euthanized were in good condition.

The bacteriological analysis revealed pure culture of the bacterium Klebsiella pneumoniae subsp. pneumoniae in the liver of seal that was killed due to breathing difficulties. Infection with this bacterium can cause pneumonia and blood poisoning and subsequently labored breathing and death. However, it is unclear whether this bacterial infection is the principal cause of deaths among the seals. The National Veterinary Institute is awaiting further laboratory results to get closer to an explanation.

No evidence of phocine distemper virus (PDV) could be detected in relevant tissue samples by PCR analysis. Phocine distemper virus caused extensive and devastating epizootic mortalities among harbor seals in 1988 and 2002. The laboratory will hopefully continue to receive animals for relevant analyses.