Get vaccinated for pertussis: Paul Poduska, PVH’s infection control coordinator, says it's more important than ever to get a pertussis vaccine.

By Gary Kimsey | University of Colorado Health

Whooping cough, an ages-old infection that’s easily transmitted, has reached epidemic proportions in Colorado.

Also called pertussis, the illnesss causes violent coughing, sometimes so bad that seizures break ribs. In some cases, severe coughing creates spasms that cause vomiting.

This temporarily stops the coughing, but three or four minutes later coughing fits resume. The coughing can also result in the onset of pneumonia.

There have been more than 700 cases statewide this year. The Larimer County Department of Health in August advised people to get vaccinated against pertussis.

Most young and middle-aged adults today received a pediatric version of Tdap vaccine when they were infants or young children. However, many people don’t know that the vaccine wears out around the age of 11, decreasing immunity to pertussis as the years continue to pile onto a person’s age.

The adult version of the vaccine—the type available to employees—protects a person throughout the rest of his or her life. The only caveat is that a tetanus booster shot is needed every decade.

“It’s more critical than ever for adults of all ages to get vaccinated," said Paul Poduska, infection control coordinator at Poudre Valley Hospital. "We expect to see more pertussis cases as children go back to school and spread the disease from one to the other.”

Although exact figures are unknown, it’s estimated that as high as a third of the students in Fort Collins schools may be not vaccinated, Poduska says.

Reasons for increase

Meanwhile, the number of older adults—those in their 60s and beyond—who become infected with pertussis has been on a steady rise, the CDC says.

Three possible reasons exist. The pertussis bacterial strain may have evolved over time and can now more easily infect older adults who were vaccinated as youngsters, or newer forms of vaccine created to decrease side effects may be less potent. Another possible reason: It was only recently—two years ago, in fact—that the Tdap vaccine for 65 years or older was approved, and then only for those who come into close contact with infants.

The net result: All of these possibilities open the way for infected grandparents to pass along pertussis to their young grandchildren.

Caused by the bacterium Bordetella pertussis, the fastidious disease produces ultra-tiny bacteria-infected droplets that are expelled into the air as a person coughs or sneezes. This makes transmission easy from person to person.

Pertussis kills about 195,000 people a year worldwide, even though vaccines exist for children and adults. In the U.S. The worst recent outbreak has been in states along the Pacific Ocean, particularly California. Thousands of people have come down with whooping cough; six have died.

In Colorado, 60 cases occurred in infants less than a year old from Jan. 1 to July 29, while 388 children from ages 1 to 14 were stricken with the illness. The remaining 165 cases occurred in adults and adolescents 15 years or older. Of all of those cases, 89 were reported in Boulder and 97 in Denver. By Aug. 11, the number of total cases had soared to 715. In comparision, the annual number of cases during the same period per year from 2007 to 2001 was 158. These stats came from the Colorado Department of Public Health and Environment and Larimer Coiunty Department of Health.

In Larimer County, 39 cases were reported through Aug. 11, compared to the average of 10 per year for the same period for each of the years ranging from 2007 to 2011. Most cases occurred during the time school was out for the summer, a period when the transmission of pertussis is usually low. Now that schools are in session, the number of cases locally and statewide are expected to increase.

'More critical than ever to get vaccinated'

In encouraging vaccinations for employees, Poduska calls to mind an epidemiology phenomenon that makes its more critical than ever for people to get vaccinated.

From the late 1960s to about a decade ago it was common—in fact, it was almost viewed as a patriotic duty in American society—for parents to have their children vaccinated against tetanus, diphtheria and pertussis. This trend was an offshoot of the polio vaccination push that began in the early 1960s and resulted in vaccinations of all school children.

About a decade ago the percentage of infants and young children who should have been inoculated with the Tdap vaccine began to decline. The reason was information that linked the Tdap vaccine to autism in children. The link, however, has yet to be scientifically validated.

As a result, the number of childhood pertussis case soared from a historic low in 1976 to major annual increases in the last few years; between 2008 and 2009, for example, a 60-percent increase occurred in infants under the age of 6 months, the age group at the greatest risk for severe illness and death.