More whooping cough in Seattle area
A family waits to get vaccinated against whooping cough at a Seattle health clinic. A whooping cough epidemic has broken out in Washington state, according to the Washington State Department of Health. Over 600 cases have already been reported this year. Reuters

Whooping cough, also known as pertussis, has reached epidemic levels in Washington state, according to the Washington State Department of Health. Over 600 cases have been reported as of Saturday, compared to only 94 cases over the same time period last year.

Whooping cough is a highly contagious bacterial disease that initially causes runny nose, fever and a mild cough and progresses into fits of rapid coughs followed by the telltale high-pitched whoop sound and vomiting, according to the Centers for Disease Control and Prevention.

The infection lasts up to 12 weeks, giving it the nickname the 100 day cough, but antibiotics reduce the severity of the symptoms. A series of vaccines administered between 2 months and 6 years of age can prevent the disease.

However, people don't realize that vaccination doesn't last forever. Adults need a booster shot every 10 years, and when they fail to stay vaccinated, it creates an opening for a whooping cough outbreak, according to the Washington State Department of Health.

Many adults don't realize they need to be vaccinated, or they assume they have been, Dr. Maxine Hayes, Washington state health officer, said in a statement. We're asking everyone to verify with their health care provider that they're up-to-date on vaccines. We're also asking everyone to use good health manners - like cover your cough and stay home when you're sick - that will also help prevent spreading whooping cough.

However, some doctors are seeing cases of whooping cough children who are vaccinated.

We have a real belief that the durability [of the vaccine] is not what was imagined, Dr. David Witt, an infectious disease specialist at Kaiser Permanente Medical Center, told Reuters. We started dissecting the data. What was very surprising was the majority of cases were in fully vaccinated children.

However, Dr. Joel Ward, a researcher at the Los Angeles Biomedical Research Institute, told Reuters the benefit of the vaccine is hard to argue against.

The disease has diminished markedly with the use of it, he said. The benefit has been enormous.

Pertussis affects over 48 million people worldwide every year and results in almost 300,000 deaths, according to a 2010 study.

The epidemic is particularly worrisome for babies, who can get whooping cough from adults and other family members, according to the department of health. Whooping cough can cause pneumonia, convulsions or encephalopathy, a disease of the brain, in babies, according to the CDC. One in 100 babies who get whooping cough will die.

We're very concerned about the continued rapid increase in reported cases, Mary Selecky, Washington state secretary of health, said in a statement. 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 [the vaccine] to be vaccinated to help protect babies that are too young for the vaccine.

Four infants died from whooping cough in Washington over the last two years.

California had a particularly bad outbreak of whooping cough in 2010, according to the CDC. Ten infants died after more than 9,000 people contracted the disease, the highest number of reported cases in 63 years.