Pertussis is spreading more than usual this year, locally and statewide, the Snohomish County Health Department said in a news release.

Ten confirmed or probable cases of pertussis have been identified in county residents so far this year. In the three previous years, there have been no more than three cases per year reported in Snohomish County.

Statewide, more than 200 cases had been reported as of mid-May, according to the Washington State Department of Health, compared to 24 cases reported in the same time period last year.

“We are likely entering an epidemic year for pertussis,” said Dr. James Lewis, Health Officer for the Snohomish County Health Department. “This would occasionally occur pre-pandemic, and this year’s resurgence of pertussis could be larger than a typical epidemic year prior to the COVID-19 pandemic. Many folks have fallen behind on immunizations and that, combined with the lack of pertussis circulating in recent years, has likely decreased overall immunity within the broader community.”

Also known as “whooping cough,” pertussis is a potentially serious illness caused by bacterial infection. Anyone at any age can become sick. For adults and older children, it is typically a mild illness. However, it is particularly dangerous for anyone younger than 1 year of age. Infants can end up hospitalized and the disease can be fatal for them. No pertussis-related deaths have been reported this year in Snohomish County.

DTaP or Tdap vaccines protect against pertussis. While people who are immunized can sometimes become infected and spread infection to others, they generally have mild disease themselves. Even people who are mildly ill can transmit illness to others who are at higher risk, the health department said. It’s recommended you talk to your health care provider if you have been exposed to pertussis and develop any symptoms, even mild ones.

Most of the cases reported so far (six of 10) have been among children younger than 5 years old. However, it’s important for people of all ages to take steps to keep themselves and others healthy. Recent local cases range in age up to the 65-and-older demographic.

Health department staff said they also are working to respond to multiple reported cases at a high school in the Edmonds School District. A letter has been provided to help notify staff, students and families.

What you can do:

Check that you and your family are current on pertussis vaccination (DTaP or Tdap vaccine, depending on age). You can talk to your health care provider or access your immunization record by going to https://app.myirmobile.com/WA. Babies and young children should receive multiple doses of DTaP between ages 2 months and 6 years. Preteens (ages 11-12) or any teen or adult who has not yet been vaccinated should receive the Tdap vaccine. Though fully vaccinated individuals still may become sick, they are much less likely to catch and spread pertussis. And if they do get sick, they usually have a milder illness.

If you are pregnant: Talk to your health care provider and make sure you receive a Tdap vaccine between weeks 27 and 36 of pregnancy to help protect your newborn. Avoid close contact with anyone who has a severe or prolonged cough, or who has been diagnosed with pertussis and has not yet completed treatment.

Watch for symptoms of pertussis. Symptoms may include runny nose, sneezing, and cough. If you know you have been exposed to pertussis (for example, if you receive notification from a school or child care), contact your healthcare provider if any symptoms develop. If you do not have any known exposures, contact your healthcare provider if symptoms worsen rather than improve over the course of one to two weeks. As it worsens, coughing may occur in fits or spasms and be followed by vomiting or a “whooping” sound. Some infants do not develop a cough but do have significant difficulty breathing.  If your doctor suspects pertussis, it is important to get tested and follow all instructions for treatment, which may include antibiotics for you and your household contacts. For children with pertussis, be sure to keep them out of school until five days of treatment have been completed.

Keep up with basic illness prevention steps. Wash your hands thoroughly and often. Stay home and away from others if you have symptoms of illness. Cover coughs and sneezes or consider wearing a mask when in crowded indoor spaces while illness is circulating.