The number of whooping cough cases on the North Olympic Peninsula has nearly doubled in the past two weeks, the region’s public health officer reported Tuesday.
Jefferson County had 18 known whooping cough — or pertussis — cases as of Tuesday, while Clallam County had five, said Dr. Tom Locke, public health officer for Clallam and Jefferson counties.
On Feb. 23, Jefferson County had 10 confirmed whooping cough cases and Clallam County had four.
Of the 23 pertussis cases on the Peninsula so far this calendar year, 21 have afflicted children ages 6 months to 14 years. The other two cases affected adults.
“It’s certainly a lot in comparison to previous years,” Locke said.
Pertussis is a highly contagious bacterial disease that can be fatal in very rare cases.
It leads to violent coughing that causes a distinctive whooping sound as sufferers gasp for breath.
Locke said the relatively high number of pertussis cases this year is consistent with other rural counties in Washington state.
The state Department of Health reported 175 confirmed cases through Feb. 18, compared with 59 for the same period in 2011.
“There’s a natural cycle of pertussis outbreaks that we know of, and we’re at the crest of one of those waves,” Locke said.
But the driving force behind the outbreak is a decline in immunizations, health officials say.
Parents who believe the whooping cough vaccine is unsafe or unnecessary create a recipe for outbreaks, Locke has said.
Just 22 percent of those who have come down with whooping cough in Jefferson County this year were fully immunized, Locke said.
He said the pertussis vaccine is about 85 percent effective.
Locke added that the same things that prevent the spread of influenza — covering your cough and staying home from work or school when you’re sick — can stem the spread of pertussis, which does not have the same seasonal variation as the flu.
Those who are in close contact with a whooping cough sufferer are given antibiotics so they don’t get sick themselves.
“We can see pertussis all year long, but the outbreaks sort of burn themselves out after awhile,” Locke said.
“We are hopeful that these current outbreaks will come under control in the next month or so.”
Meanwhile, flu season has not started on the Peninsula, and it’s getting more and more likely that the region will be spared from a seasonal outbreak, Locke said.
Locke, who monitors influenza activity closely and declares the official start of flu season in Clallam and Jefferson counties when necessary, said the virus has been relatively mild in Western Washington this winter.
Flu seasons that begin in March or April are less severe than those that begin in January or February, Locke has said.
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Reporter Rob Ollikainen can be reached at 360-417-3537 or at rob.ollikainen@peninsuladailynews.com.