A prolonged mumps outbreak among highly vaccinated Aboriginal people in the Kimberley region of Western Australia
Revle D Bangor-Jones, Gary K Dowse, Carolien M Giele, Paul G van 
Buynder, Meredith M Hodge and Mary M Whitty
MJA 2009; 191 (7): 398-401

To describe a prolonged outbreak of mumps in the Kimberley region of 
Western Australia in 2007–2008.

Descriptive analysis of all mumps cases notified to the WA Notifiable 
Infectious Diseases Database for the period 1 July 2007 to 30 June 2008.
Main outcome measures:

Notified cases of mumps by patients’ place of residence, age, 
Indigenous or non-Indigenous ethnicity, vaccination status and method 
of diagnosis.

84% (153/183) of mumps notifications in WA over the study period 
occurred in the Kimberley region or were directly linked to Kimberley 
cases. Median age of patients was 18 years (range, 2–63 years), and 
54% of patients were aged less than 20 years. Almost all (92%) were 
Australian Aboriginal people; 67% (102/153) had received at least one 
dose of mumps vaccine, and 52% had received two doses. The highest 
notification rate (1816 cases per 100 000 population) was in the 
Aboriginal 15–19-years age group, and 92% of these patients had 
received at least one dose of mumps vaccine. Almost all outbreak cases 
(94%) were laboratory confirmed. Genotyping was performed on 20 mumps 
virus isolates: all were genotype J.

A prolonged outbreak of mumps occurred in a well defined, highly 
vaccinated, predominantly young Aboriginal population in the remote 
Kimberley region of WA. This outbreak raises questions about the 
effectiveness and scheduling of the current vaccine (which is genotype 
A-derived), especially for Aboriginal people. Surveillance of 
circulating mumps virus genotypes and neutralisation studies will help 
in evaluating the protection provided by the current vaccine against 
genotypically different strains.