(CBS News) - Washington State has currently reached epidemic levels of whooping cough. The Washington State Department of Health reported that 640 cases have been reported in 23 counties as of March 31, compared to only 94 cases during the same time period last year.
"We're very concerned about the continued rapid increase in reported cases," said Secretary of Health Mary Selecky said in the press release. "This disease can be very serious for young babies, who often get whooping cough from adults and other family members. We want all teens and adults who haven't had Tdap to be vaccinated to help protect babies that are too young for the vaccine."
According to the Center for Disease Control, whooping cough - real name pertussis - is a common disease in the U.S. It has periodic occurrences every three to five years, with more frequent outbreaks.
The National Institute of Health reports that the disease is an upper respiratory infection caused by a bacteria. Severe coughing starts 10 to 12 days after being exposed to the bacteria, but the infection can last about six weeks. When a person sneezes or coughs - creating a deep "whooping" sound - the bacteria spreads through particles in the air. Left untreated in infants, it can cause disability and possibly death. It can infect people of all ages.
One of the big problems whooping cough is posing right now is that the vaccination shots, which are usually given to children, can wear off over time. The Washington State Department of Health is recommending that everyone checks their vaccination records to see if they are up to date, and those age 11 or older get a whooping cough booster shot, known as a Tdap, to prevent the spread to infants. All children under 19 will receive a free vaccine at any of the state's participating Childhood Vaccine Program locations.
A federal advisory board voted in late February to recommend that all those 65 and older who haven't got a whooping cough shot as an adult should get one,reported. The adult vaccine combines protection against tetanus, diphtheria and whooping cough, and costs about $35 a dose.
The waning effect of the vaccines was also observed in a March 2012 study published in Clinical Infectious Diseases. Researchers in California observed 132 patients under the age of 18 who tested positive for whooping cough. They found out that 81 percent of them were up to date with their whooping cough shots, 11 percent did not complete the series and eight percent received no vaccination whatsoever.
Regardless if they were vaccinated or not, the study revealed that the number of whooping cough cases peaked around the pre-teen ages. On average, the researchers aid there were 36 cases for every 10,000 children between 2-7 who were fully immunized that got whooping cough. The number goes up to 245 out of 10,000 with the kids between 8 and 12. That number dropped drastically after the kids reached 13, possibly because most people receive the booster shot at the age of 12.
"The longer you went from your last vaccine, the greater your risk of disease," Witt told Reuters Health.
California is an especially interesting case to investigate because they recently had an outbreak of the disease in 2010. There were 9,143 cases observed, including 10 infant deaths - the most reported in 63 years.
During a conference call with The Columbian, Washington state secretary of health Mary Selecky said the epidemic has and will probably affect much more people. They estimate only 10 to 12 percent of cases are reported.
"It's probably just the tip of the iceberg," Selecky said. "We really know in public health that this is under-reported."