An epidemic of whooping cough is sweeping through South Canterbury.
There were 15 cases of whooping cough (pertussis) reported in the district in January, pushing the number of cases for the past three months up to 40.
Canterbury medical officer of health Dr Daniel Williams said those "epidemic levels" were likely to continue for "some months".
He said notifications increased first in Temuka in the summer of 2011-2012, followed by Twizel in early 2012, and Geraldine and Temuka in the second half of 2012. Timaru and Waimate had an increase in cases this summer.
The message being pushed by Dr Williams following the surge in cases was to "never cough on a baby".
Whooping cough could be life-threatening, especially in very young children, he said.
However, none of the cases reported in January was in infants under the age of 1. The disease was usually milder in adults.
Whooping cough is a highly contagious bacterial infection, usually characterised by a cough.
Coughing, which lasts more than two weeks, can result in vomiting or difficulty breathing.
Dr Williams said on-time immunisation was important.
"Immunisation can prevent infection, or make it less severe if it does occur. However, immunity from both vaccination and natural infection wanes with time, and national epidemics occur in three to four-year cycles as levels of immunity in the population drop."
Whooping cough rates had also been high in the North Island and in the northern part of the South Island over the past two years.
South Canterbury has also had a range of stomach bug reports, including 15 cases of campylobacteriosis, three of cryptosporidiosis and four of salmonellosis.
The cases were reported in January and the bugs cause diarrhoea and abdominal cramps.
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