The researchers also found that 92 per cent of eastern grey kangaroos had been exposed to herpes viruses at some stage in their life.
Dr Devlin says the findings suggest that it might be wise to keep certain animals well separated in zoos, to minimise the chance of viruses jumping hosts.
"We should be careful about keeping eastern grey kangaroos together with other macropods such as wallabies," she said.
Koalas and wombats are closely related so they may also need to be kept separate, Dr Devlin added.
"Normally, wombats are on the ground and koalas are in the trees. If you have them in a zoo or a hospital where people move from one enclosure to another, that sets up transmission pathways that wouldn't be there in nature."
Dr Devlin said zoo managers can also use the new findings to work out if a virus has already jumped species, and therefore establish the urgency of keeping animals separate.
The high level of active herpes infection found in the study may be due to stress, said Dr Devlin.
"We know that stress can cause problems in terms of reactivating and making herpes virus infections worse," she said.
Stress can be caused by such things as habitat destruction and drought, but also by other diseases.
Interestingly, the researchers found that a lot of the wombats with herpes also had a chronic mite infestation called sarcoptic mange. Similarly, most of the koalas with herpes also had chlamydia.
"It could be that the chlamydia [or sarcoptic mange] is causing the animals to be really stressed and therefore they're more likely to have a herpes virus infection," said Dr Devlin.
But, she said, it could be the other way around -- that the herpes virus is stressing the animals out so they are more likely to succumb to other diseases.
Article first appeared on ABC Science.