Just as it seemed that the two were set for a long haul, Cameron was caught at deep mix-wicket off a high full toss.
Australia, who had been cruising along then, had a few hiccups as West Indies struck twice to dismiss Sthalekar and Sarah Coyte (7) to reduce Australia to 190 for six.
The Aussies couldn't utilise the powerplay overs and could score only 15 runs in those five overs, while losing three wickets.
A late attack from Jodie Fields (36) and Elysse Perry (25) helped the side to reach the challenging total.
For West Indies, Shaquana Quintyne was the pick of the bowlers scalping three for 27, while Anisa Mohammed, Shanel Daley, Tremayne Smartt and Stafanie Taylor, though expensive, picked up a wicket apiece.