Wanaka A&P show event manager Jane Stalker said the Southern District Health Board had advised other people who attended the show were "casual contacts", with a low risk of close contact to anyone carrying the virus.
"For all 'casual contact' situations, the Ministry of Health and SDHB [Southern District Health Board] are reminding people to follow the guidance of washing hands, maintaining social distancing and if people develop symptoms, they should self-isolate and call Healthline," she said.
President of the Hereford Association, Colin Corney, said he was confident all the conference delegates could be contacted and alerted to the confirmed cases.
"We have been able to contact them via email and other different means," he said.
Those in New Zealand were being asked to self-isolate.
However, Stalker said the ministry was yet to get in touch with A&P show staff for contact tracing.
• If you have symptoms of the coronavirus, call the NZ Covid-19 Healthline on 0800 358 5453 (+64 9 358 5453 for international SIMs).
- RNZ