Expert examines whooping cough epidemic

 

 

 

The green rod-shaped bacteria that cause whooping cough lodge in the tiny hair-like stems of the respiratory tract. (Photo courtesy of WebMD)

PULLMAN, Wash. – As federal disease sleuths wrap up their field investigation into Washington state’s whooping cough epidemic, a renowned infectious disease and vaccine expert visiting the Washington State University campus this week said the outbreak’s cause is no mystery.

 

The rate of whooping cough cases 10 times higher than last year is most likely driven by two main factors, said Roy Curtiss III, director of the Biodesign Institute’s Center for Infectious Diseases and Vaccinology at Arizona State University.

 

The modern-day whooping cough vaccine loses its effectiveness after five years, leaving young people vulnerable to infection, he said. And too many parents aren’t getting their children immunized – a decision often based on fear, not facts.
 
“The myth that vaccines cause autism ignited an enormous public health scare,” said Curtiss in an interview while at WSU for the 2012 Austin and Joan Larsen Distinguished Visiting Lecture presented by the veterinary microbiology and pathology department. “Not only that, but vaccines have been so successful that people look around and see no threat. They figure, why vaccinate if there’s no threat?  Believe me, there are lots of dangerous critters out there.”
 
One of those critters is the bacterium Bordetella pertussis that causes whooping cough, so named for the “Whoop! Whoop!” sound children make when trying to suck in air during coughing fits. The highly infectious disease can cause pneumonia, seizures and death, particularly among infants.

“It’s a serious illness that killed tens of thousands of children during the first half of the century. Then, with the advent of vaccines, we didn’t see much of it for decades,” said Curtiss, a microbiologist member of the National Academy of Sciences.

 

“Now it’s making a comeback,” he said.

 

And a sizable chunk of that comeback is in Washington, where health officials declared an epidemic in April. The number of cases remains “incredibly high,” said Michele Roberts of the state department of health, and could get higher with kids back in school.

 

Last year at this time, Washington had 462 cases of whooping cough. So far in 2012, there are 4,268 cases, according to the health department’s latest figures. The infection has struck mostly babies and children 10-13 years old.

 

Skagit County, an hour north of Seattle, has the highest rate, with 469 cases per 100,000 people. While few cases have been reported in Whitman County, two hours west in Yakima County, the numbers spike considerably to 381 cases.

Several dozen disease detectives from the U.S. Centers for Disease Control (CDC) in Atlanta recently spent six weeks scouring the state, trying to determine what’s behind the surge. After pouring through immunization records, interviewing physicians and examining possible environmental factors, most have returned to Atlanta with their data to work on unraveling the mystery, said Roberts.

“A study of this magnitude has never been done before,” she said.

 

Curtiss, who has spent a half-century studying and developing vaccines and in 1977 addressed the National Academy of Sciences Forum in a beard just as long as it is today, suspects they’ll find that many cases are tied to the waning immunity in children whose last booster shot lost its punch.

“The new vaccine, around since the 1990s, was developed to be safer, but what we’re seeing is that it isn’t as effective as the older version,” he said.

 

Additionally, more outbreaks occur when parents don’t get their children immunized, and Washington state is probably an example, he said.

A study released by the CDC backs that up. During the 2009-2010 school year, 6.2 percent of the state’s kindergartners received exemptions for immunizations – ranking Washington the highest in the country for parent-requested exemptions.

 

Following the study’s release, the legislature passed a law requiring a doctor’s signature in addition to a parent’s for an exemption to be granted – with the idea that parents will be better informed to make their decision, said Roberts. While the change has lowered the number of parents opting out, “we still have a ways to go,” she said.

In the meantime, the state’s epidemic continues to attract national attention, with news stories appearing in the New York Times, Forbes magazine and on network television. What’s more, health officials are waiting to see what the CDC learns from its investigation, said Roberts.
 
After a period of vaccine backlash, Curtiss said he hopes the widespread prevalence of Bordetella pertussis gets people to see that “infectious disease threats are among us and it’s the vaccines that keep them at bay. Too many well-meaning parents are making choices that feel right but end up putting the child – and the community – at risk.” 

 

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