Credit: Dave Hunt (AAP)

Six out of nine people who were in contact with a Hendra virus-infected horse at the Queensland Sunshine Coast have been cleared of infection based on the preliminary test results.

Nine people came into contact with the horse, that was put down on Monday at Tewantin.

Among those who have been cleared by the initial tests was a 12-year-old girl, while the other three are still waiting for their test findings.

Jeannette Young, chief health officer of Queensland said the preliminary tests provided a baseline for the authorities, but additional testing was required.

Dr Young says, It doesn't give us any answer about any exposure to this horse.

The Hendra virus can incubate for as long as 21 days, and all nine people exposed to the horse would take a second test again.

She says, That test will tell us if the person has any result due to exposure to this horse. Then, we do a test at 42 days post initial exposure just to clear it.

Queensland's biosecurity has started an investigation into two fruit bats colonies at the Tewantin property area.

In an effort to find useful ideas into the bats' behaviour, the scientists will be using infra-red camera technology to record the bats at night.

Hendra virus is naturally carried by fruit bats and is passed to horses through bodily fluids. It was first discovered in September 1994, when it triggered the deaths of 14 horses and a trainer in Hendra, a suburb in Brisbane.

The infected horse in Tewantin is the 41st to die since 1994.The CSIRO is looking into vaccination for horses that hopefully will be available within five years.