Download Imported seropositive animals: Assurance provided by serological tests - Import risk analysis (July 1999)

This document examines the biosecurity risks posed by the importation of live cattle, sheep, goats, horses and pigs, should any such animals be found seropositive during post-arrival quarantine after having already tested negative pre-export. On a number of occasions in the past serologically positive animals have been detected in quarantine. Each case has been dealt with on an ad hoc basis and, at times, the decisions made have been criticised by interested parties. This review aims to establish a basis for future incidents when seropositive animals are detected.

Under the Agreement on the Application of Sanitary and Phytosanitary (SPS) Measures, member countries of the World Trade Organisation are obliged to ensure that their sanitary measures are based on a scientific assessment of risk. MPI’s policy on serological positive animals constitutes an SPS measure, and as such it must be based on risk analysis.

The analysis concludes that for many of the diseases considered of importance for international animal trade there is an identifiable biosecurity risk associated with seropositive animals. However, for some diseases it is concluded that seropositive animals would not be carrying the infectious agent, and therefore could be safely released from post-arrival quarantine, albeit after a quarantine period of several months in some cases.

For some vector-borne protozoal and rickettsial diseases it is concluded that although the agent is likely to be carried by seropositive animals, the diseases would not be capable of establishment as the necessary insect vectors do not exist in New Zealand.

The analysis concludes that caution is warranted for several diseases which might be transmitted to some extent by the stable fly, Stomoxys calcitrans, for which the distribution, population density and ecology in New Zealand are not clearly understood.