Invasive meningococcal disease on the rise

ESR figures show the number of cases of invasive meningococcal disease reported has been increasing since 2014.

While, nationally, incidence of the disease remains low, in the past year there were 120 cases reported from January 1 to December 31, 2018, with 10 deaths.

That compares with 2017 when there were 112 cases and nine deaths. In 2014, 45 cases were reported.

In the past year, cases have been reported from all around the country, with just two District Health Boards unaffected.

Six of the 10 deaths last year were due to the group W meningococcal disease (MenW).
Late last year, the Ministry of Health announced the launch of a targeted vaccination programme in Northland to control a community outbreak of the MenW strain.
The increasing numbers of MenW prompted ESR to increase the frequency of its reporting on cases of the strain to the Ministry of Health.

A public health physician at ESR, Jill Sherwood, says the number of cases of MenW has risen over the past three years from five in 2016, 12 in 2017 and to 33 in 2018.
“Meningococcal B, which was the cause of the large outbreak of the disease in the 1990s and early 2000s, remains the dominant strain in New Zealand.

“But with the increase we’re seeing in MenW cases, we may now be following the trends in others countries. In Australia, for instance, MenW became the dominant strain in 2016.”

Compared to 2017, ESR figures for the past year show the proportion of MenW cases has increased (from 12 per cent to 29 per cent) and the proportion of group B cases has decreased (from 67 per cent to 45 per cent).

For group B notifications in the past year, cases were reported for all age groups except in the 70 years and over, with the highest number of cases and the highest rates reported in those aged under five, and adolescents aged 15–19 years.

While the number of cases reported was highest in the New Zealand European ethnic group, the rates were highest in the Māori and Pacific peoples’ ethnic groups. There were three deaths reported due to group B disease in 2018.

Invasive meningococcal disease is caused by bacteria called Neisseria meningitidis, of which there are several different groups. The most common groups seen worldwide are A, B, C, W, X and Y and these groups account for most cases of invasive disease.

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