Phocine distemper revisited: Multidisciplinary analysis of the 2002 phocine distemper virus epidemic in the Netherlands

April 1988, excess mortality of seals was observed on Anholt, a small Danish island in the Kattegat17. This announced the start of an epidemic that killed between 18 000 and 23 000 seals in European waters in 1988, mostly harbour seals (Phoca vitulina)17,28. The cause of this mortality was initially unknown, but through intensive research during the epidemic was shown to be a novel morbillivirus, subsequently named ‘phocine distemper virus’ (PDV)13,43,48. May 2002, excess mortality of seals was again observed on Anholt. This time, PDV was a known virus, and laboratory tests were available to rapidly confirm the diagnosis34. Because PDV was immediately diagnosed, and both sero-monitoring of harbour seals34,67 and models14,23 had predicted a highly susceptible harbour seal population in 2002, decision makers were easily be made aware of the likely impact the disease would have on the harbour seal population and the need to prepare for the event and monitor it. It turned out the Netherlands would have five weeks to prepare for the epidemic: the 1st case of PDV was diagnosed on June the 16th 200258. The Ministry of Agriculture, Environment and Food Quality took the coordination, consulting parties involved in seal conservation and care (e.g., Seal Research and Rehabilitation Centre SRRC, EcoMare) or wildlife health research (Department of Virology of the Erasmus MC, Dutch Wildlife Health Centre), as well as governmental coastal and island institutions (e.g., municipalities, coastguard) and others (e.g., rendering facilities) and taking the final decisions on the outbreak management and monitoring strategy.