Test results are expected to confirm the death of a sixth horse from the deadly Hendra virus.
Queensland Biosecurity officials confirmed the death of the horse at Park Ridge in Logan City.
Staff were currently determining whether properties in the immediate area needed to be quarantined due to the possible interaction of horses from neighbouring places.
There was only one horse on the suspected Park Ridge property.
Preliminary assessment has confirmed that two people had contact with the horse. That means there are now 25 people being monitored for the virus after having contact with infected horses.
The virus is carried by native fruit bats but can be passed to horses. In seven known instances, the virus has been passed on to people, and proved fatal in four cases.
The latest death brings the toll in Queensland to five, with one death in New South Wales - all in little more than a week.
Biosecurity Queensland and Queensland Health staff are currently doorknocking neighbours in Park Ridge to gather information on their animals and give them information about Hendra virus.