A sudden surge in whooping cough has been recorded in the Hutt Valley and Wellington, with 17 probable or confirmed cases already this month.
Medical officer of health Margot McLean, says there were about 14 cases per month for most of the year, but that shot up to 41 in October.
Dr McLean says those affected are aged from under one to a person in their 80s.
The Ministry of Health says there are higher than usual levels of whooping cough in five areas of the country, but it is not considered to be a national epidemic at this stage.
The West Coast is the worst affected area, with 140 confirmed cases since the start of May and the end of October.