This year’s whooping cough season is shaping up to be just as bad as — if not worse than — last year’s as the disease again reaches epidemic levels both locally and nationwide.

So far, said Sophia Yager, Boulder County Public Health immunization coordinator, confirmed pertussis cases in the county are up to 193. Last year at this time, the number was 170.

One of the reasons for the increase may be waning immunity of the vaccine, with some of those who are vaccinated still contracting the disease as the vaccine’s effectiveness wears off over time. She said pertussis also is cyclical, with spikes typically seen every three to five years, and diagnostic testing has improved.

“All of those things combined are why we’re seeing more cases,” she said.

She said the most cases are being seen in school-age children, who account for 139 of the cases. Of those, she said, the hardest hit are children 13 to 18.

Boulder’s Fairview High, where a parent reported nine confirmed cases and another four possible cases, is one example of the current prevalence of the disease.

Yager said cases are widespread across the county and aren’t concentrated in one particular community or school.

“We’re just seeing it all over,” she said.

Susan Rowley, the Boulder Valley School District’s health services coordinator, said the district sends out letters to parents when there are more than one or two cases at a school. She said the district and the health department also track cases closely to look for patterns.

Health officials are continuing to encourage people to make sure their vaccinations are up to date.

The Centers for Disease Control recommends that infants get their first round of the vaccine at 2 months. The vaccine series is finished before a child turns 6, with a booster at age 11 or 12. Last year, the CDC also began recommending that pregnant women get vaccinated in their third trimester.

Pertussis is spread when an infected person sneezes or coughs. Symptoms of pertussis usually develop seven to 10 days after exposure, but they can develop from four to 21 days later. In infants and young children, whooping cough can lead to hospitalization, seizures, long-term neurological problems and even death.

Symptoms in the first week mimic a cold, including a runny nose and sore throat. In the second week, there’s severe coughing that can continue for up to three months. After a coughing fit, someone with pertussis often needs to take deep breaths, resulting in a “whooping” sound.