Parents warned to be vigilant as whooping cough outbreak spreads

The recent outbreak of whooping cough (pertussis) in the South Island could be the start of a new epidemic as the disease spreads through the Otago region - according to the author of a University of Auckland study1 into whooping cough.

Dr Kathryn Philipson says whooping cough epidemics occur in three to five year cycles, and the recent outbreaks in the South Island highlight the fact the deadly disease is never far away.

She says pertussis is a “difficult bug” and parents need to be vigilant when it comes to protecting their children not just in infancy but during their school years also.

“We know these epidemics come in cycles and in the South Island it is four years since the last one.”

In just over a week there have been 102 cases of suspected pertussis reported to the Southern District Health Board2.

“During epidemics it generally takes a while to move around the country so people can be more affected in Otago right now, but in three or six months it could be in Hawke's Bay or Auckland,” she says.

Dr Philipson says while immunisation provides protection it’s not permanent and New Zealanders need to make sure they take ongoing steps to protect themselves and their families.

“Pertussis is always circulating, even at low levels in the community, and often people are unaware they have the disease.”

An Auckland cough study1 found that 17% of school-aged children who visited the doctor with a persistent cough of two weeks duration or longer had recently had a whooping cough infection – and this was not during the peak of an epidemic.

Dr Philipson’s study, The Cough Conundrum (COUGH), found that one in 10 individuals identified in primary care with acute persistent cough had pertussis1. She says the main reason for difficulty in diagnosing pertussis was that symptoms such as cough duration were similar to other causes of a persistent cough.

Her research also found that the rate of whooping cough in children was more than twice that for adults.

Diagnosis of pertussis, says Dr Philipson, is always a challenge as it must always be distinguished from other cough illnesses.

“In winter time there are simply more cough illnesses and people may not go to their doctor or think it is not unusual to have a cough if they believe they have had the flu for example,” says Dr Philipson.

She says with many cases not being diagnosed this presents a significant risk to the most vulnerable members of society - infants who are under the age at which immunisations can be administered

“Any cough that lasts over two weeks could be pertussis, but if you or your child has been in contact with someone who has been diagnosed with whooping cough it’s important to get to a GP as soon as possible as antibiotics can be administered early in the illness,” she says.

Along with the difficulty in diagnosing pertussis, care needs to be taken when interpreting national figures for the disease, she says.

“For some communities the burden of pertussis could be even more significant than it seems when we look at national figures.

“The national statistics can be a little bit misleading. If you look at the statistics for a whole year it might seem that it’s been a quiet year for whooping cough, but if you look at particular regions they can have much higher rates, so when these statistics are combined for the whole country it doesn’t look like a bad year.”

Dr Philipson says New Zealanders should always be aware of the dangers of pertussis.

“It’s a deadly disease for infants and a long disrupting illness in older children and adults, and while the message for the protection of infants seems to be getting through, we also need to ensure school age children receive their boosters.

On-time immunisation, with a whooping-cough vaccine at six weeks, three months and five months of age is necessary to protect infants against whooping cough. Four and eleven-year-olds also need to receive their boosters on time.

Along with the cost to a child or person's health there is a huge social burden for the families affected by the disease, she says.

“I’ve seen mums and dads up half the night for three months, it affects their work, their marriage, their kids, it’s not insignificant at all,” she says.

Dr Philipson says all families and close friends of those with a young baby, should discuss pertussis immunisation with their doctor. Relatives and friends should also be advised not to visit if they have a cough or cold.

Kiwis are urged to visit their GP for more information or to book a booster vaccination.

References:

  1. The Cough Conundrum - Br J Gen Pract 2013;DOI: 10.3399/bjgp13X670705
  2. Pertussis in Central Otago Update

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