Newcastle disease outbreaks in Italy during 2000

Inquiry into Newcastle disease epidemic in Italy

Source: I. Capua et al
Veterinary Record May 4 2002
starts p565, 4 pages long

There was an epidemic of Newcastle disease in central and northern Italy, following a serious epidemic of avian ‘flu, in 1999 and 2000. Newcastle disease is caused by a virus, avian paramyxovirus serotype 1, and is extremely contagious, as well as serious, with a death rate of over 50% for chickens.

The preceding avian ‘flu epidemic lead to the loss of more than 13 million poultry from infection and culling. This meant that eggs were imported from outside Italy, and chickens were kept in greater stocking densities where the ‘flu epidemic had not hit, since supply had dropped elsewhere. Vaccination programmes to protect against Newcastle disease were reduced or abandoned because the population was not homogenous, and there were also fears of the impact of reactions to vaccines where the birds were overcrowded.

These conditions favoured the emergence of Newcastle disease, and 254 outbreaks were dealt with from May 5 2000 to December 31 2000. Backyard flocks accounted for 219 of the outbreaks, 17 occurred at dealers, with a further 17 at intensively reared establishments, and one ostrich farm was hit.

The symptoms included listlessness, depression, tremors and wing paralysis, with birds dying between 24 and 48 hours after showing symptoms.

The infection was traced to a broiler hatchery, which had imported eggs from elsewhere in Europe, and the disease then spread to dealers, and from dealers to farms. The most susceptible birds were guinea fowl and chickens, with ostriches, pheasants and turkeys also affected, but less susceptible. The disease may have entered the hatchery through faeces on egg shells. It is not clear where it came from, but it may have been undetected in countries using a vaccination programme, since it is more likely to be detected where the population is immunologically naïve, where the clinical disease is more likely to appear.

There is a need for more monitoring to detect the disease in Europe. There were also problems during the Italian epidemic due to the large numbers of backyard flocks involved. Imposing a protection and surveillance zones for many small flocks involved a great deal of effort. There is a case for less stringent controls, since outbreaks tend to be self-limiting when they occur in naïve backyard flocks. There are problems in defining ‘backyard flocks’ and this could be done by looking at where the birds are slaughtered and consumed, and whether consumption is local, or whether the birds go into the industrial circuit.