The biggest ever outbreak of Australia\'s deadly Hendra virus has spread to near the tourist city of Cairns, claiming the life of an eighth horse, officials said Tuesday. The animal died on a farm west of Cairns the hub for the Great Barrier Reef after showing signs of Hendra, which can cause respiratory illness in humans and has killed four of the seven people it has infected since 1994. The horse died on Monday, said Jim Thompson, Queensland state\'s chief biosecurity officer. It is the sixth Hendra case on Australia\'s populous east coast since June 20, and the furthest north the virus, which is spread by the fruit bat or flying fox, has been seen during the current outbreak. Jeannette Young, the state\'s chief health officer, said it was uncertain how many people had been exposed in the latest case. At least 32 people have already been exposed to the rare virus in the current outbreak, with one case just 500 kilometres (300 miles) from Sydney, the furthest south the virus has ever been found. Officials at Randwick, Sydney\'s best known racecourse, have warned trainers to be alert for symptoms of the virus, which is spread from infected bats via half-chewed fruit or water and food contaminated by their urine and droppings. Named after the Brisbane suburb in which is was first detected in 1994, Hendra is thought to be unique to Australia.