The highly contagious type 1 bursal disease virus (IBDV type 1) has been confirmed on two Otago hen farms owned by Mainland and in close proximity to each other.

While the disease poses no risk to humans it has virtually stopped the chicken meat export trade to Australia, which required a guarantee New Zealand was free of the disease and is worth an estimated $50 to $60 million annually. 

Tegel, which operates three plants around the country, is the main exporter of chicken meat across the Tasman but its export certificate was cancelled after the virus was detected.