The "super strain" of maningococcal disease claimed that six lives this year could become the dominant form in New Zealand if rates continue to trend in overseas, scientists say.
The Institute for Environmental Sciences and Research (ESR) began to report Meningococcal Meningitis Weekly (MENW) every week, after jumping from five in 2016 to 24 this year.
GPs and emergency departments were asked to be alert about the possible symptoms.
The fatal cases included seven-year-old Wengeri, Alexis Albert, whose grieving mother begged for a nationwide vaccine and consciousness program, and 16-year-old Derrick Hodder, who died in a hospital in Auckland shortly after a youth camp.
Meningococcal disease is a bacterial infection that causes meningitis – an infection of the membranes that cover the brain – and septicemia, or blood poisoning.
While Meningococcal (MenB) has long been the dominant tension in New Zealand, causing two thirds of the disease, there have been growing concerns about the rise of MenW.
The proportion of MenB cases dropped from 67 percent in 2017 to 49 percent over the year to date, while MenW rates climbed from 11 percent to 28 percent.
ESR Public Health Dr. Dr. Sherwood said the increase in the last two years was "significantly higher" than the average annual messages for 2012-2015 when only 2.5 cases were notified.
The tension was particularly worrisome, as it was harder to diagnose, much more venomous, and involved higher mortality rates – potentially up to 15 percent of the time.
It also affected a wider age range, with more than 40% of cases of adults over the age of 40.
Against this background, New Zealand may follow trends in other countries, such as Australia, where MenW became the dominant species in 2016.
"Although the number of MenW cases in New Zealand is still relatively low, there is a growing trend in messages and a recent change in the type of continuum similar to England, Australia and Canada."
Whether or when MenW was bypassing MenB was difficult to predict, as case numbers were few, Sherwood said.
ESR monitoring of maningococcal disease by searching patterns based on basic demographics such as age, sex, ethnicity, location, residence arrangements and performance dates.
"For maningococcal disease we also reviewed species strain type and some cases with the same strain group that were not known to have been closely associated with each other occurred within specific populations over the past three months."
In the early 2000s, the government developed a nationwide vaccination program following an outbreak of men, but since then has released the vaccination schedule.
However, the government was currently considering public funding and vaccinations against new strains of maningococcal disease – including MenW.
The director of the Center for Immunization Research, Professor Nicky Turner, said New Zealand had vaccinations for several high-risk groups that could be purchased, but they were not on the national schedule.
"I am aware that our authorities have continued to think about introducing these vaccines to New Zealand," Turner said.
"It's a little complicated and many factors must be considered."
Turner noted that vaccines, while effective, did not give protection for life.
"The disease occurs mainly in infants, young children and adolescents, and the organism is usually performed in the throat of adolescents, but not exclusively," she said.
"Schedules that focus on these two ages may be the most effective, we already have a lot of vaccinations on the baby schedule, so adding others can be done, but it's not simple.
"Adolescents may also need a dose, and now we have a vaccine schedule in middle age, but not in high school, which may be a better age to go through the higher risk years of later adolescents before the vaccine dwindles."
The other complex issue was the role of "herd immunity" – in which a predominantly immune population can help protect the few who do not.
"If we were to campaign for all the young people, we might be able to reduce the carriage of the organism in the throat of people and thus prevent further diseases before introducing a vaccine on schedule."
New Zealand was not the only country struggling with the best way to manage the disease, she said.
"I believe there is definitely a role for vaccinations here, but unfortunately they will not be a magic bullet."
According to the numbers
W rate of all cases of maningococcal disease this year – six of them fatal – from 11% last year.
49% The group's dominant rate in this year's cases, compared with 67 percent last year.
15% The potential rate of MenW cases that are fatal.
40% At least four out of 10 cases involve patients over the age of 40.