Pertussis epidemic grips state

Several dozen cases have been reported here, but a local health official says the real number of infections is likely in the hundreds.

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— It's been the year of years for whooping cough in Washington state. The Department of Health released an update on Tuesday that puts the number of documented cases so far this year at 3,014 through July 14. In 2011, 219 cases had been reported for the same time frame.

The puts the ratio of pertussis at 44.8 cases per 100,000 state residents, according to health officials. There have been 185 babies younger than 1 reported as having the disease, and 39 of those hospitalized. Of those, 31 were 3 months of age or younger.

Children ages 10-13 have the highest incident rate -- 218 cases per 100,000 in the age range in the state.

The numbers are probably only the tip of the iceberg, noted Harvey Crowder, administrator for Walla Walla County Public Health Department.

"If it is any indication about what we've seen with other infectious disease conditions, there is usually about 10 unreported cases for every case that gets reported. That happens for a variety of reasons -- no health insurance, people don't want to go, the treating physician calls it something else."

In a media briefing this morning, Dr. Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases and Mary Selecky, secretary of the state Department of Health, spoke of the disease's impact.

While Washington state has been prominently affected by the disease, "This is not just a Washington story," Schuchat pointed out. "It is spreading around the U.S. We think a number of states are at risk right now."

Pertussis is a "very easy disease to catch," Selecky said. This state has the world's attention and there is much to be learned by what is happening here, she added. "We are learning from this, most adults don't even think about being vaccinated."

A 2010 national survey showed the number of adults getting pertussis booster shots hovers at just over eight percent. Schuchat told reporters. "We know we can do so much better, particularly in pregnant women."

Babies under age 1, who are at highest risk for severe illness or death from contracting whooping cough, typically get infected through their mothers or other family members, which is devastating to families who have gone through it, Selecky said. "It is incredibly hard ... it is tragic."

While no infants have died in Washington during this wave, the last peak year, 2010, killed 27 people nationally out of 27,000; 25 of those were infants, Schuchat noted.

As of today, 18,000 U.S. cases have been reported to the Centers for Disease Control and Prevention, more than twice as many as last year and more than each of the last five years. The disease peaks every three to five years, but health officials are seeing a gradual and sustained increase across the country, Schuchat said.

A report on the Washington epidemic was published today in the CDC's weekly publication. It highlights more reported cases among 13- to 14-year-olds, which is a changing trend across the country that indicates a shorter duration for vaccine protection against whooping cough.

Experts are investigating if that might be due to a switch in vaccine structures in 1997, when the U.S. stopped using whole-cell vaccine -- with more serious side effects -- to an acellular vaccine with milder symptoms in response to public concerns. The acellular vaccine, administered in recommended doses, has a good safety and effectiveness record, Schuchat said.

That said, no vaccine works as well as everyone wishes. "Vaccines have done a good job, but they're not perfect."

Children who are not vaccinated are at eight times the risk for getting the disease, she added.

Information from a study done during the 2010 California whooping cough outbreak showed that the DTaP vaccine for children works well for the first couple years after vaccination. The data also showed that the protection decreases to about 70 percent effectiveness five years after vaccination.

Most children in Washington state are vaccinated, Selecky said. As well, Vaccinated people who get whooping cough have milder symptoms, shorter illnesses, and are less likely to spread the disease to others. "Our biggest concern is keeping babies from getting sick and vaccination is still the best protection."

CDC officials are studying cases in Washington to blueprint a number of factors, including possibly changing the recommended booster periods and numbers of doses in adults, how the state government is working with physicians to determine how to diagnose for whooping cough and using funds to create public awareness and purchase more vaccine. "If we run out of vaccine, that will be a good thing," Selecky told those attending the briefing by phone this morning. "We'll buy more."

In Walla Walla County, 43 cases have been reported so far, meaning there are more likely 400-500 cases, Crowder added. The county has free whooping cough immunization for uninsured people age 19 and over, and "adequate" vaccine for those 18 and under. "Right now, cost is not a barrier to anyone getting vaccinated for pertussis, for adults or for kids. It's never too late to vaccinate."

Public health staff in Walla Walla has been steadily vaccinating for the disease as the epidemic has continued, he said. "Not a ton, but a lot."

His office is asking people to call 524-2650 for vaccination appointments. "We've done away with long waits with the appointment system."

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