SYDNEY –  The cause of a mystery eye ailment that struck about 50 visitors to a dairy pavilion at an agricultural show in Australia has been traced -- to cow urine.

The Royal Adelaide Show had to close its dairy cattle pavilion after an rising number of people reported sore eyes when visiting the judging marquee.

Officials from the South Australia (SA) Health Department were called in to investigate and found the cause of the outbreak was stagnant cow urine.

Show spokeswoman Michelle Hocking told local reporters that a recent spell of wet weather may have created conditions within the pavilion where ammonia from cow urine was released.
About 30 people were treated on site by volunteers from the first aid group St. John Ambulance but about 20 went to the emergency department of the Royal Adelaide Hospital.

"From our institutional memory we can't recall an incident of this nature before," Peter Jackson from the St. John Ambulance told Reuters.