Confirmed cases of whooping cough in Northamptonshire are running at almost nine a month on average, latest figures for 2012 show.
The Health Protection Agency issued the statistics along with a warning that the cyclical virus is almost seven times more prevalent than the last major round of cases in 2008.
It said Northamptonshire had seen 89 cases between January and the end of September this year, although it added the true number could be higher as not all individual samples from suspected cases are tested and confirmed when there is a mini-outbreak.
A vaccine for pregnant women has now been introduced in response.
Dr Mary Ramsay, head of immunisation at the HPA, said: “We have been very concerned about the continuing increase in whooping cough cases.
“The introduction of a vaccine for pregnant women will not have an immediate impact on serious infection in infants so vigilance remains important.”
Although there have been 10 deaths of babies across England and Wales this year and the disease is highly infectious, it is understood there have been no deaths at Northampton General Hospital in 2012 and it does not usually lead to serious complications.
Signs include severe coughing fits accompanied by the characteristic “whoop” sound in young children.
Whooping cough, also known as pertussis, affects all ages. Young infants are at highest risk of severe complications and death from whooping cough because babies do not complete vaccination until they are about four months old.
In older children and adults whooping cough can be an unpleasant illness but it does not usually lead to serious health concerns.
It spreads when a person with the infection coughs and sheds the bacteria which is then inhaled by another person.