A baby and young adult have been diagnosed with the potentially deadly meningococcal disease in the past week and are recovering in separate West Australian hospitals.
The cases are not linked and are different types of the bacterium that causes the disease, the WA Health Department says.
Close contacts have been provided with information and antibiotics and a vaccine, where appropriate, to minimise the chance of further spreading the organism.
The department said the cases were a timely reminder of the increased risk of the disease during winter and spring.
Meningococcal disease is a life-threatening illness caused by a bacterial infection of the blood and/or membranes that line the spinal cord and brain, and occasionally other areas such as large joints.
Twenty-three cases were reported in 2016 and there have been 12 cases this year.
