Fear meningococcal ‘superstrain’ could become dominant

AUCKLAND: A ‘‘superstrain’’ of meningococcal disease that has claimed six lives this year could become the dominant form in New Zealand if rates follow overseas trends, scientists say.

The Institute of Environmental Science and Research (ESR) has begun reporting each week on group W meningococcal disease (MenW), after the number of cases jumped from five in 2016 to 24 for this year.

GPs and emergency departments have been asked to be vigilant about possible symptoms.

Fatal cases have included Whangarei 7yearold Alexis Albert, whose grieving mother has pleaded for a nationwide vaccination and awareness programme, and Kerikeri 16yearold Dion Hodder, who died in Auckland City Hospital soon after becoming ill during a Motutapu Island youth camp.

Meningococcal disease is a bacterial infection that causes meningitis — an infection of the membranes that cover the brain — and septicaemia, or blood poisoning.

While meningococcal B (MenB) has long been the dominant strain in New Zealand, causing two thirds of cases of the disease, there are growing concerns over the rise of MenW.

The proportion of MenB cases dropped from 67% in 2017 to 49% over the year to date, while rates of MenW have climbed from 11% to 28%.

ESR public health physician Dr Jill Sherwood said the increase in the past two years had been ‘‘significantly higher’’ than average annual notifications for 201215, when only 2.5 cases were notified.

The strain was particularly worrying as it was harder to diagnose, was much more virulent and was implicated in higher death rates of possibly up to 15% of cases.

It also affected a broader age range, more than 40% of cases involving adults older than 40.

Concerningly, it was possible New Zealand might be following trends seen in other countries, such as Australia, where MenW became the dominant strain in 2016.

‘‘Although the number of MenW cases in New Zealand is still relatively low, there is an increasing trend in notifications and a recent change in the sequence type similar to the UK, Australia and Canada.’’

If or when MenW did overtake MenB was hard to predict, as case numbers were few, Dr Sherwood said.

The ESR monitored meningococcal disease by looking for patterns based on basic demography such as age, sex, ethnicity, location, living arrangements and onset dates.

‘‘For meningococcal disease we also review group and strain type and how many cases with the same strain and group who were not known to have had close contact with each other have occurred within specific populations within the past three months.’’

In the early 2000s, the government rolled out a nationwide vaccination programme following a MenB outbreak, but it had since been taken off the vaccination schedule.

However, the Government was now considering publicly funding vaccinations against the new strains of meningococcal disease including MenW.

Immunisation Advisory Centre director Associate Prof Nikki Turner said New Zealand had vaccines for some highrisk groups that could be bought, but they were not on the national schedule.

‘‘I am aware that our authorities have, and are continuing to, put thought into introducing these vaccines to New Zealand,’’ she said.

Prof Turner noted that vaccines, while effective, did not give lifelong protection. — NZME