Describing the illness as "something I thought I'd never, ever get", Senator Williams confirmed he was diagnosed 12 months ago after experiencing difficulty with his left leg.

Universally known as "Wacka", a childhood nickname, the outspoken New South Welshman encouraged other men to see their doctor if they encountered health problems.

"Too many men, when they have a problem, bottle it up," he said on Sky News on Friday. "It builds up inside [and] serious things happen. You've got to get it off your chest, speak to people."

Senator Williams thanked his wife Nancy, his friends and his political and parliamentary colleagues for their support.

He said he had experienced some pain and difficulty when walking, especially in his left leg, but had otherwise avoided serious symptoms or associated depression.

However, some friends, including his Nationals colleague Dr David Gillepsie, had their suspicions.

"It affects each individual differently. I don't have tremors. I'm not shaking," Senator Williams said.

"The good news is they're making a lot of research. We're very lucky to live in these years when our medical profession and our research has developed so many solutions in solving so many of these problems."

Senator Williams, 62, has already announced plans to retire at the next election, and doctors have advised him he should be able to serve the two remaining years of his term.

Since his election in 2007, he has used his position in Parliament to crusade against dodgy financiers, bankers, businessmen and the big end of town.

Among his targets have been supermarket giants Coles and Woolies, the corporate regular, ASIC, and perhaps most notably the Commonwealth Bank.

Wacka was at it again just a fortnight ago, grilling CBA's head of wealth management on whether consultants Deloitte had actually interviewed any customers during its investigation into the scandal-plagued life insurer CommInsure.

"I'm just a dumb broken-down old shearer," he said, frustration evident. "Did Deloitte speak to customers, yes or no?"

The answer was no.

Asked on Friday about his many years of combat with the industry, Senator Williams was modest. "I'm just trying to right the wrongs," he said. "I just think people should be treated fairly."

In a message for Wacka's 60th birthday, then prime minister Tony Abbott described him as "one of the parliament's great characters", as well as "a voice for those who have no voice".

Parkinson's disease, which affects about 70,000 Australians, involves the loss of cells in parts of the brain and a decline in the production of dopamine. It can be slow to progress, but usually comes to impair a person's movement, balance, posture, mood and memory.

The cause of the incurable disease remains a mystery. On average, 32 Australians are diagnosed with the condition every day, according to the Shake it Up Australia Foundation, and it is the second-most common neurological disease in the country after dementia.

Senator Williams remained resolute on Friday. "We can manage this," he said. "So far, so good."

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This story originally appeared on www.smh.com.au