19 October 2005, a suspicion of Newcastle Disease (ND) occurred in a Danish layer flock of poultry of 45,000 animals. The suspicion was based on a drop in egg production of 80% and a few animals showing clinical signs of ND with lameness and neurological disorders. The mortality and morbidity have been low. PCR conducted on tissue from examined birds displaying clinical symptoms appeared positive for PMV-1 virus. Serological investigation of 60 birds showed titres of 32-4096.
High pathogenic type
21 October 2005, the sequencing of the PCR products from kidney and brain indicated that the virus is the high pathogenic type, which may end up with an ICPI >0.7. The flock was established a few weeks before the Danish ND-vaccination status was changed from non-vaccinating to vaccinating country and was one of six unvaccinated flocks in Denmark.
Based on the results of the sequencing, the Danish Veterinary and Food Administration decided to cull the affected flock and establish protection (3 km) and surveillance (10 km)zones around it. The culling of the flock started 21 October 2005 and was finalised during 24 October. When the culling was initiated, the staff from the regional veterinary service reported on the occurrence of many animals with clear clinical signs and increased mortality.
Serological investigation of the culled layers without clinical signs from the two other houses were seronegative for Newcastle disease suggesting that the birds were not infected by the disease. However, all the poultry in the three houses on the premises were culled.
Six recorded direct contacts to broiler flocks
There were only six recorded direct contacts to broiler flocks, which had received day-old-chicks originating from hatching eggs from the affected flock. These chickens were hatched 10 October 2005, and the hatching eggs were laid 14-15 September 2005 – more than 21 days before the disease problem started. Due to precautionary reasons, these animals were checked both serologically – broilers are not vaccinated against ND – and by PCR, and the results were negative.
The protection zone
The protection zone around the Newcastle Disease-affected holding in southern Jutland was lifted as of 25 November 2005, 21 days after the approval of the preliminary cleaning and disinfection. The protection zone is hereafter a part of the surveillance zone.
The regional veterinary authorities have visited and clinically inspected 2 commercial and 24 hobby holdings inside the protection zone without finding any clinical signs of Newcastle Disease.
The regional veterinary service has registered 3 commercial and 187 hobby holdings in the surveillance zone. There has been no indication of any disease problems in these holdings.
The surveillance zone was lifted as of 4 December 2005.
Newcastle Disease in Denmark in 2002 (final report)