Three-quarters of the cases of meningococcal disease in WA so far this year have been caused by rare W strains that very few people are vaccinated against.
Figures obtained by The Weekend West shows nine of the 12 cases of the disease this year have been linked to strains from the bacteria group W.
Type B caused the other three.
Meningococcal disease is a rare, life-threatening illness caused by a bacterial infection of the blood or the membranes that line the spinal cord and brain.
A young WA child — the 12th case this year — died from the disease last week.
In the past, there has been virtually no local cases caused by W strains, but there were two in 2014, four cases last year and nine this year.
The WA Health Department said this week it was monitoring the trend, which was also being seen in States including Victoria and could have implications for vaccination recommendations.
Victorian authorities have seen a sharp rise in a group W strain known as ST11, which was responsible for 4 per cent of meningococcal cases in 2013 but 30 per cent of cases last year.
At present, a vaccine to protect against type C meningococcal disease, historically the most common in Australia, is free for children and given at 12 months.
A vaccine against meningococcal B, the most common type in WA, is available but not government-funded. There is a privately funded vaccine against W strains, but it is usually only advised for overseas travellers.
The Health Department spokesman said while the overall number of invasive meningococcal disease in WA had been falling since 2000, there had been a recent increase in cases linked to W strains.
Source: The West Australian Newspaper 24/09/2016