There are now 27 COVID-19 cases in Mandurah after one new case was recorded today, two on Sunday and eight at the end of last week.
The WA Health Department's 'heat map' shows four of the five WA councils with the most cases have aging populations.
Among them is Mandurah, with the state's highest proportion of seniors - 22.6 per cent of residents over the age of 65.
The other four councils considered "hotspots" because they have 20 or more cases are Stirling, Joondalup, Wanneroo and Melville.
Meanwhile, there are 18 coronavirus cases in neighbouring Rockingham, four in Serpentine-Jarrahdale and none in the Shire of Murray, Waroona or Boddington.
The 'heat map' is an online tool - which can viewed by anyone at healthywa.gov.au - that displays only cases of WA residents and excludes numbers from cruise ships and other non-WA cases.
Read more:
Current coronavirus testing criteria changed last Thursday, with all WA residents experiencing a high fever and acute respiratory illness now eligible for testing.
Chief Medical Officer Brendan Murphy today urged Australians not to ignore any other health issues, saying some GPs are reporting a sudden drop in patients.
"They're very worried that people are so frightened that they're not seeking medical attention," Professor Murphy said.
"You can go and see a doctor. Please don't neglect general medical health conditions."
Prime Minister Scott Morrison today urged Australians to stay at home this Easter weekend, saying failure to do so "would completely undo everything we have achieved so far together".
Mandurah mayor Rhys Williams this week also reminded residents not to travel over Easter and urged Perth people to stay away from the Peel region.
Read more: