Senator Patrick, a South Australian, of the Centre Alliance, said he had insisted on a test after attending a Senate committee hearing with Liberal Andrew Bragg on March 9. Senator Bragg tested positive after attending a wedding at Stanwell Tops, where as many as 35 people contracted the disease.

Senator Patrick said the Senate had contacted him about Senator Bragg's result last Tuesday, March 17, and immediately self-isolated. He didn't qualify for testing because he had no symptoms, but he had pushed for a test given the amount of travel involved in his work.

"I had been in and around South Australia over the preceding week before I found out. I thought it best to get tested and insisted on doing so," he said.

"I'm upset that I have been in contact with other people, obviously before I knew of Senator Bragg's situation, but hey, this is the nature of the situation that we're in now. And my message to everyone is please exercise social distancing."

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Senator Patrick said he had still shown no symptoms, now two weeks after his contact with Senator Bragg, but would stay in isolation until he had had a negative test.

Nor had anyone with whom he had been in contact with shown symptoms, and he had had no contact with parliamentarians since the Senate superannuation committee hearing on March 9. Senator Patrick did not attend Monday's parliamentary session.

"The normal incubation period is about five days so one would have expected for me to have experienced them by now," he said.

"The beautiful thing is being a former sub mariner I'm well trained in self isolation," he said. "I can live in small spaces for up to six or eight weeks."

Two Labor senators at the meeting, Jenny McAllister and Tony Sheldon, have also been in isolation. Senator McAllister tested negative; Senator Sheldon hasn't been tested. The isolation for both ends on Tuesday.

Home Affairs Minister Peter Dutton was the first of now four federal parliamentarians to test positive for the virus, with suspicions he was infected on a flight to the United States on March 4, or while in the US, where he met Donald Trump's daughter Ivanka Trump and other senior officials in the Trump circle.

Nationals Senator Susan McDonald, who is a Queenslander like Mr Dutton, also has coronavirus.

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