It's raising concerns for those most vulnerable to the bacterial disease. It spreads through air droplets that can live on clothes and surfaces for up to five days. The symptoms often begin as a common cold and progress into coughing fits that can last for weeks.
The cough's scariest sound is that of young lungs gasping for air, who are most vulnerable to the infection.
Symptoms include a cough that sounds like "whoop," a runny nose and nasal congestion.
Pertussis is "called whooping cough because as the diaphragm squeezes the lungs to try to get all that stuff out, it forcefully pushes the lungs up," said pediatric hospitalist Dr. Gabrielle Pina at Loma Linda University Children's Health.
Even scarier is when you can't hear infants breathing.
"They develop apnea because the diaphragm literally can't do that. So they just stop breathing for 20-plus seconds, which is terrifying," Pina said.
The CDC reports a 10-year high in whooping cough cases with more than 17,000 reports so far.
Americans are experiencing five times as many cases as compared to last year, with many in California.
"It looks like it's coming back with a vengeance," Pina said.
Pertussis numbers are returning to pre-pandemic levels, a time when masks and social isolation were more common and many families skipped childhood vaccines.
"If you are in a community that does not get regularly vaccinated, you're at high risk for getting these vaccine-preventable illnesses like pertussis," she said.
Babies less than a year old are at the greatest risk of developing an infection and severe complications, with a third of them ending up in hospitals.
Pertussis is a respiratory tract infection that can usually be treated by antibiotics, but only prevents the bacteria from spreading further.
Adults, especially the immunocompromised and the elderly, need a Tdap booster vaccine every 10 years, while pregnant women are recommended to get it at 27 weeks gestation.
"Because we really want those third trimester stores of the antibodies to cross into the babies so that they have the most protection," Pina said.
Pina expects cases to rise even more and recommends getting vaccinated, keeping newborns at home and avoiding crowds.
"Wash your hands. Wash your hands. And if you feel ill at all, please wear a mask because you're helping to prevent the spread," said Pina.