Increase in Meningococcal Serogroup W Disease, Victoria, Australia, 2013–2015

In Victoria, Australia, invasive meningococcal disease caused by Neisseria meningitidis serogroup W increased from 4% of all cases in 2013 to 30% in 2015. This increase resulted largely from strains similar to those in the serogroup W sequence type 11 clonal complex, previously described in the United Kingdom and South America.