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THURSDAY, July 19 (HealthDay News) -- The number of whooping cough cases in the United States may hit a record high this year, federal health officials reported Thursday.
"Many states are seeing higher than expected cases of pertussis [whooping cough]," Dr. Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases at the U.S. Centers for Disease Control and Prevention, said during a noon news conference. Pertussis has already caused the death of nine infants this year, she added.
As of Thursday, almost 18,000 cases had been reported, Schuchat said. "That's more than twice as many as we saw last year at this time. In fact, that's more than we've seen in the past five years. We may be on track for a record-high pertussis rate this year."
Washington state illustrates the troubling trend.
Between January and June, more than 2,500 cases of whooping cough were reported there, a 1,300 percent increase from 2011, health officials said.
Most of these cases were seen among teens aged 13 to 14, despite the fact that most of these adolescents were vaccinated as young children, according to the CDC.
"What is happening in Washington state is a reflection of the larger national picture of this very difficult-to-control disease," Schuchat said.
And, as with most diseases, reported cases are only a small percent of actual cases because most go unreported, she noted.
Although pertussis comes in waves every three to five years, the current outbreaks are also probably the result of waning effectiveness of the pertussis vaccine, Schuchat noted.
Pertussis rates are the highest since a historic low in the 1970s, she added.
Because pertussis vaccination starts after the age of 1 and infants are especially vulnerable to the disease, Schuchat urged people to get a pertussis booster. Vaccination is especially important for pregnant women and others who come in contact with infants, she noted.
The report is published in the July 20 issue of the Morbidity and Mortality Weekly Report, a CDC publication.
The outbreak in Washington state is only the tip of the iceberg, researchers stressed. Similar reports are coming in from all over the nation, according to the report.
Dr. Marc Siegel, an associate professor of medicine at NYU Langone Medical Center in New York City, said that "this is happening because the pertussis vaccine lasts only about 10 years."
"It looks like it was less effective than everybody thought it was," he added. "So, we have ended up with a reservoir of cases in high school and college students."
Schools, Siegel said, are a fertile breeding ground for bacteria such as pertussis. "This is a very easy bacteria to transmit," he explained.
In addition, doctors often fail to diagnose it because they aren't looking for it, Siegel said.
The solution to stopping the spread of pertussis is a revaccination campaign; people should probably get a booster shot every 10 years, Siegel said.
Although pertussis is usually not fatal in teens and adults, it can be deadly in young children and infants, Siegel noted.