Rubella, mumps could soon be history
Rubella has been all-but eliminated and the country may be close to getting rid of mumps amid evidence of an increase in vaccination rates.
Research published by the Commonwealth Health Department in its latest Communicable Diseases Intelligence report suggests that rubella, a mild infection in adults that can nonetheless cause severe congenital abnormalities in unborn babies, is no longer endemic, while the country is close to eliminating mumps despite a recent upsurge in notifications of the disease.
Four years after the Americas were declared rubella-free, researchers from the National Centre for Immunisation Research and Surveillance said it was now so rare in Australia – aside from cases involving infections imported from overseas – that arguably the country met all the criteria for the World Health Organisation to declare it eliminated.
To be declared rubella-free, a country or region must have a low incidence of infection, with only sporadic imported cases with limited spread, high levels of immunity and a robust immunisation program.
Between the mid-1990s and 2005 the average annual notification rate for the disease tumbled from 14.8 per 100,000 to 0.23 per 100,000 by 2005, and there have been just two reported cases of congenital rubella syndrome since 2008. The proportion of imported rubella cases, meanwhile, climbed from 9 to 27 per cent between 2005 and 2012, and the immunisation rate has held above 91 per cent.
The researchers said it only remained to improve surveillance, including genotyping infections to establish their origin, to demonstrate the absence of endemic strains and have Australia declared rubella-free.
Researchers have also held out hope that mumps may soon be eliminated from Australia, if it is not already.
Mumps became a notifiable disease in 2001, and its incidence peaked at 2.8 per 100,000 in 2007 before slipping below 1 per 100,000 by 2012.
As with other countries, there has been an increase in the average age of people with mumps following the introduction of universal child vaccination in 1989. Between 2008 and 2012, it was much more common among 25 to 34-year-olds (1.7 cases per 100,000) than among young children. Those aged one to four years had the lowest incidence, just 0.5 per 100,000.
But researchers admitted that, despite high vaccination coverage against mumps (94 per cent for the first dose of the measles, mumps, rubella vaccine and 90 per cent for the second dose), there was an increasing trend in mumps notifications and the likelihood its incidence was being under-reported.
Nevertheless, that said it was possible that Australia was among those countries to have achieved, or come close to, eliminating the disease, adding that, “sporadic outbreaks in highly vaccinated populations may be due to the force of infection after virus introduction from an endemic area into high-density, high contact environments”.
They concluded that the trend toward increased notifications required careful monitoring.
The possibility that rubella and mumps may soon be eliminated, if they are not already, has come amid evidence that the nation’s vaccination rate is increasing.
The Federal Government has mounted a crackdown on parents who refuse or fail to ensure their children are vaccinated, threatening to withhold benefits worth thousands of dollars from families and abolishing all but medical exemptions.
But even before these latest measures were announced, figures from the Australian Childhood Immunisation Register show vaccination rates were rising in mid-2014, reaching 91.5 per cent of one-year-olds (up 0.6 of a percentage point), 92.8 per cent of two-year-olds (up 0.2 of a percentage point) and 92.2 per cent of five-year-olds (up 0.3 of a percentage point).