Whooping cough outbreaks in Canada tied to lower vaccine immunity
Adults should also have a pertussis booster at least once to help protect themselves and newborns
The bacterial infection, which often but not always causes a "whoop" sound when breathing or coughing, is particularly dangerous for very young babies, say doctors. The disease can lead to hospitalization and, in rare cases, death.
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Most of those who developed the infection had not been inoculated against pertussis, which is included in a vaccine that typically also protects against diphtheria, tetanus and polio. Some provinces also include Haemophilus influenzae type B vaccine (Hib) or hepatitis B in the shot.
Most of those who got sick were young children, but some teens and adults also contracted the infection, Routledge added.
Whooping cough is the second most common infectious childhood disease in Canada, after influenza. While the disease is endemic, or always present in the community to some extent, outbreaks tend to be cyclical, with a spike in cases every two to five years.
Pertussis often mimics cold viruses in its symptoms — runny nose, nasal congestion, red and watery eyes, and fever — but its signature hallmark is a cough and severe wheezing that can persist for weeks. As with cold and the flu, the highly contagious disease is passed through saliva and mucus from person to person.
New Brunswick has also been dealing with a pertussis outbreak. The province has recorded 56 confirmed cases this year, all in the Greater Moncton area, including four new cases reported between Nov. 6 and Nov. 12 in residents aged nine to 24, a spokesman said.
While Ontario has had some isolated outbreaks, Dr. Shelley Deeks said 2015 has "not been a huge year" for pertussis, at least compared to some previous years.
In 1997, Canada switched to an "acellular" vaccine that had fewer side-effects than the whole-cell vaccine previously used. But the newer vaccine has been found to be less effective over time than the old one, creating what doctors call waning immunity — and possibly leading to a rise in cases.
"So adults should talk to their physicians and make sure they receive a dose of pertussis," she said, noting that the shot would typically also contain diphtheria and tetanus components.
British Columbia is also seeing a bit of a jump in whooping cough his year, with double the number of cases reported in 2012, but half the case count in 2000 — reflecting the cyclical nature of the infection, said Dr. Danuta Skowronski, an infectious disease expert at the BC Center for Disease Control.
While the goal of public health officials isn't to eradicate pertussis — an impossible goal given its endemic nature — it's not clear how more-consistent protection can be achieved.
"Do you add more doses? Or are we approaching the kind of program like we have with influenza … where you have to give it annually or at least every few years?"
"It's most important that we get that first dose into children in a timely way, without delaying. Parents should be on that."