Unanswered questions, the epidemiology of a community outbreak: meningococcal C disease in Northland, New Zealand, 2011.

AIM We describe the epidemiology of a community outbreak of Meningococcal C disease in Northland in 2011, and national trends in serogroup C disease in New Zealand. METHODS Notification data from EpiSurv for all meningococcal C cases were analysed for 2011 for Northland and for the period 2001-2011 nationally. RESULTS In 2011, the rate of group C meningococcal disease for the population in the Whangarei district aged less than 20 years was 27.6 cases per 100,000 population (6 cases) compared with 17.6 cases per 100,000 population under 20 years (8 cases) in the Northland District Health Board (DHB). All except one case were under 20 years of age. The case fatality rate was 33%. Nationally the rate of meningococcal C disease has fluctuated over the last decade, with an increasing trend apparent since 2007. There has been a noticeable increase over the last 3 years of group C cases infected with the C:P1.5-1,10-8 strain (including all of the Northland cases). This strain has also been associated with a higher case fatality rate (16% in the period 2007-2011). CONCLUSION Meningococcal C disease in New Zealand, although still less common than group B, is poorly understood. The relationships between carriage, invasive disease and community outbreaks deserve greater study. Active monitoring of surveillance data is warranted to ensure timely funded introduction of the highly effective meningococcal C conjugate vaccine on to the national immunisation schedule when appropriate, given increasing disease rates, the high case fatality rate and significant Maori non-Maori inequities in disease incidence.