The number of people reported with whooping cough, also known as pertussis, is rising in the United States. As of June 1, 2024, more than double the cases of whooping cough were reported as of this date in 2023. Whooping cough is returning to its more typical pre-pandemic cyclic patterns of more than 10,000 cases a year.

According to CDC preliminary data, reported cases were more than twice as high last year compared to the same time period the previous year. Note that these numbers can change as health departments and CDC finalize the data.

Reported cases of whooping cough were lower than usual since the COVID-19 pandemic. It’s likely that preventative actions used during the pandemic (e.g. good hygiene and distancing) lowered transmission.

Whooping cough is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis. It’s known for the “whoop” noise when someone gasps for air after a coughing fit. It affects about a third of those who get this infection.

People with whooping cough spread the disease by coughing or sneezing while in close contact with others, who then breathe in the bacteria.

Symptoms usually appear seven to 10 days but can appear from four to 21 days after a person is exposed. It is rare but it can take up to six weeks to develop symptoms. Some people have milder symptoms, especially if they have been vaccinated.

Complications of whooping cough are more common in infants and young children. Those complications may include pneumonia, middle ear infection, loss of appetite, sleep disturbance, fainting, dehydration, seizures, altered brain function (encephalopathy), brief periods when breathing stops and death.

A person with whooping cough can pass it to others as soon as they get cold-like symptoms. They can also pass it up to three weeks after they start coughing. If the infected person takes an appropriate antibiotic, they will not spread the germ after five full days of treatment.

It is very important for adults to make sure they are up to date with their pertussis-containing vaccines if they spend any time with infants. This includes parents, grandparents, siblings, babysitters, relatives and friends.

Pregnant women should receive Tdap in the third trimester of every pregnancy to pass immunity to their newborn until the baby is old enough to begin shots at two months of age.

Travelers should be up to date with pertussis-containing vaccines before they travel. Whooping cough occurs everywhere in the world.

Notify your health care provider if you or someone in your family—particularly children— has symptoms, especially children.

The best way to prevent whooping cough is to get vaccinated.

Michael Kossove is professor emeritus and adjunct professor of microbiology at Touro University, School of Health Sciences.