It's the archaic sickness that struck down 18th century sailors, but dreaded scurvy has resurfaced in modern day Sydney.

Penelope Jackson became the first of a number of people in western Sydney to be diagnosed with the scourge of the seas.

"I couldn't believe it. I thought, hang on a minute, scurvy hasn't be around for centuries," Ms Jackson said.

"It's something you associate with the First Fleet and the days of Arthur Phillip and Captain Cook. You don't expect it to be around in the 21st century," she said.