Increased Pertussis Activity Reported In Montana

The number of pertussis cases in the United States has increased this year compared with recent years and appears to have returned to its more typical pre-pandemic patterns. Between 2016–2019, an average of 17,800 people in the U.S. were sickened with pertussis each year. As of Oct. 5, 17,579 people in the U.S. have been reported with pertussis infection, which is a notable increase from the low number of pertussis cases reported from 2020–2023. Montana has also had an increase in the number of reported pertussis cases in the last several weeks. Forty-five cases of pertussis have been reported in Montana in 2024, with 28 of those cases occurring since Sept. 1. Pertussis cases have been reported in 14 Montana counties, with outbreaks reported in two communities.

Pertussis is a vaccine-preventable disease that is spread via respiratory droplets when talking, coughing, or sneezing. It generally takes 5 to 10 days for symptoms to develop after someone has been exposed, but sometimes symptoms do not appear for 21 days. Pertussis symptoms are initially similar to the common cold, including runny nose, low-grade fever (less than 100.4°F), and a mild cough. Young infants with pertussis may experience apnea, or life-threatening pauses in breathing, instead of a cough.

Pertussis progresses to involve a paroxysmal cough or coughing fit. Coughing paroxysms can occur for up to 6 weeks, but sometimes pertussis symptoms can last longer (hence the name 100day cough). Vomiting and/or a characteristic high-pitched “whoop” on inhalation after a coughing fit are characteristic of the disease. People usually seem well in between fits, but have difficulty sleeping at night, struggle to breathe, or may fracture (break) a rib due to severe coughing. Recovery from pertussis is slow, but the cough lessens over time. Vaccinated people may have a milder illness than unvaccinated individuals.

Complications of pertussis are most common in young infants, especially those under 6 months. Approximately 1 in 3 infants with pertussis require hospitalization. Common complications among babies under 1 year old include apnea (68 percent of hospitalized babies), pneumonia (22 percent) and convulsions (2 percent).

Treatment for pertussis works best when started early in illness. Standard treatment is a five-day course of azithromycin. Antimicrobial treatment administered less than 3 weeks after cough onset limits transmission to others. Persons >1 year of age who have been coughing longer than 21 days generally do not require treatment as it is not effective later in illness and the person is no longer contagious. However, infants <1 year old and pregnant women with pertussis should receive treatment when diagnosed within six weeks of cough onset.

Vaccination is the best way to prevent pertussis before exposure. Vaccination with DTaP is recommended in 5 doses at two, four, six, 15 to 18 months and 4 to 6 years. A dose of Tdap is then recommended at age 11 to 12 years. CDC recommends pregnant women receive a dose of Tdap with each pregnancy. CDC recommends adults receive at least one lifetime dose of Tdap and then vaccination with Td or Tdap every 10 years.

It can be difficult to distinguish between pertussis and other respiratory pathogens based on clinical symptoms alone, especially early in illness when antibiotics are most helpful. Prompt testing can help detect pertussis infection among other similar presenting illnesses. Some individuals with pertussis may be co-infected with other pathogens, such as COVID-19, rhinovirus, enterovirus, and respiratory syncytial virus. Cases of parapertussis have also been detected in several communities in Montana.

Recommendations for the Public: 1) Make sure you and your family are up to date with pertussis vaccination. Talk to your medical provider if you are unsure when you received your last dose. The recommended immunization schedule is for children to receive five doses of DTaP during early childhood and then one dose of Tdap at age 11 to 12 years. Adults are recommended to get a Tdap every 10 years and pregnant women should get a dose during each pregnancy.

2) Seek medical care if you or your child have difficulty breathing, violent coughing, or pauses in breathing.

3) Stay home from work or school when you are ill and keep sick children home to prevent spreading illness to daycare or school classmates. It takes everyone to keep our communities safe and healthy.

For more information, contact Roosevelt County Health Department at 406-653-6223. Vaccination hours each week are walk-in on Tuesday, Wednesday, and Thursday, from 9 to 11 a.m. and 1 to 4 p.m.