Science Centres: Aquatic Biodiversity and Biosecurity

Part of a Risk Atlas map for Canterbury, showing pig densities within a 10 km radius of piggeries and the frequency of conditions favourable to airborne spread of FMD (yellow, orange, and red segments indicate highest risk conditions).

NIWA scientists have produced a ‘Climatological Risk Atlas’ for foot-and-mouth disease (FMD), based on an analysis of weather conditions that would favour the airborne spread of the virus.

While New Zealand has never experienced an FMD outbreak, Biosecurity New Zealand commissioned the Atlas to better prepare for such an event. Airborne spread of FMD is not common. However, airborne dispersal can be difficult to control and, when the right disease and weather conditions coincide, rapid and far-reaching.

Airborne plumes of FMD are mostly likely to be spread on fine, clear nights, when winds are light, there isn’t much turbulence, and humidity is more than 55%. Pigs are the most likely spreaders of airborne FMD, and cattle the most likely receptors.

By analysing weather patterns over the last five years, we produced seasonal risk maps for night and day conditions for five important pig farming regions of New Zealand: South Auckland, Waikato, Taranaki, Manawatu, and Canterbury.

The Atlas shows the risk of spread to and from saleyards, including the hypothetical risk of the saleyards being in the path of a highly concentrated FMD plume for typical high risk weather conditions, assuming outbreaks at certain large piggeries.

Biosecurity New Zealand has used this information to prepare risk profiles for selected saleyards and piggeries around New Zealand.