By Stephanie Stahl

PHILADELPHIA (CBS) — A health watch warning: A potentially deadly cough is spreading in both Pennsylvania and New Jersey, according to the state health departments.

Doctors are seeing a growing number of cases of pertussis, also known as whooping cough because people aren’t getting the needed vaccine booster. One South Jersey family says the lack of awareness almost killed their son.

The Sena family is happy to finally have their 11-week-old baby, Marco, home again and getting better after a scary episode with pertussis.

“It was the distinctive whoop. He would go like that, but then he would stop breathing,” explained Amy Sena, Marco’s mother.

Marco’s parents say he was repeatedly misdiagnosed until they took him to the Children’s Hospital of Philadelphia, where Marco was admitted to the intensive care unit. The final diagnosis was whooping cough, a bacterial infection of the respiratory system.

“It can be difficult to diagnose in babies, and there’s not a good treatment for it,” said Dr. William Sharrar, a pediatrician with Children’s Regional Hospital at Cooper. He did not treat Marco, who was just five weeks old at the time, and ended up being hospitalized for weeks.

“We just didn’t think he was going to make it. About every thirty minutes, he would stop breathing. He would just gasp for air, and stop breathing,” said Amy.

Marco is lucky; many babies with whooping cough don’t survive. They can’t be vaccinated until they’re two months old, and it’s contagious, so anyone around a newborn needs to be vaccinated or get a booster.

“The scary thing is that we did not know anything about it. I was given a booster, but it was never conveyed that maybe the husband should get his booster, grandparents, anyone that comes and visits the baby,” said Amy.

“It does wear out over a number of years, and you need to be revaccinated,” said Dr. Sharrar.

The Sena family doesn’t know who may have infected Marco, but they want other parents to know about the potential danger of not getting vaccine boosters.

“This didn’t have to happen to him,” said Amy.

Doctors say adults with pertussis don’t always have obvious symptoms and may not even realize they’re infected.

For more on pertussis, click here.

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