Pertussis — whooping cough — is making a highly contagious comeback, health officials warn. And it's being found across northern Utah in unusually high numbers.

Salt Lake Valley Health Department, for instance, has confirmed 26 cases and is investigating another 50 in the June-to-August time period. Over that same time period last year, seven cases were confirmed, said Pam Davenport, department spokeswoman.

The Bear River and Weber-Morgan health departments are among those reporting an unusual increase in cases.

"There are several factors in this," said Dr. Dagmar Vitek, SLVHD epidemiologist. "Some parents are not vaccinating children. And some children are under-immunized, so the efficacy is lower."

She warns that if you come in contact with someone who has the illness, "you will get it. It's very, very contagious."

Young children are supposed to receive a diphtheria-tetanus-pertussis vaccine in five doses between birth and the time they enter grade school.

"After so many years of not having pertussis, parents have slacked off in getting the series. Sometimes a child will have one or two, but not five. And adults are usually not as sick, so they carry around this cough and give it to kids, who run the risk of some real severe complications," Davenport said.

The vaccination only provides protection for five to 10 years after the last dose, and there is no comparable vaccine for teens and adults. The U.S. Food and Drug Administration is reportedly expected to approve a pertussis booster for patients 11 to 64 years in the next six months or so.

Last year, nationally, the illness hit a 30-year high and Utah numbers are much worse this year than last.

The number of confirmed and suspected cases is also believed to be an undercount because adults get less serious symptoms and most don't have cultures taken when they're ill, even when it drags on and on, as pertussis does.

"The symptoms are milder, so adults go to a doctor and are diagnosed with bronchitis and sent home," Vitek said.

On the misery scale, pertussis is not for pansies. It can, though rarely does, kill children younger than age 1, and it's a long-lasting illness that starts like a common cold, with runny nose, sneezing and a low-grade fever. In its second stage, uncontrolled coughing fits take over. When someone breathes in, a whooping noise may result, hence the nickname. That stage can last more than two months. Sometimes the coughing is so severe a person may vomit. It also disrupts sleep, according to information from the Centers for Disease Control and Prevention.

Like many respiratory illnesses, it's spread by droplets in the air from someone sneezing or coughing. And it's extremely contagious at first, becoming less so over time.

One reason it may be spreading, Vitek said, is the very real concern about antibiotic resistance and the concerted push to teach doctors "please don't put someone with a cold on antibiotics," since it won't help. But pertussis is a bacterial illness, unlike a cold, which is viral. It does respond to specific antibiotics, which if correctly prescribed can lesson symptoms, duration and even how contagious the illness is.

The only way to make a correct diagnosis is to take a culture of mucus from the back of the nose, something Vitek said should be done as well if "someone has bronchitis that isn't going away," since it may not be bronchitis. If the test is positive for pertussis, family members and close contacts should also be given antibiotics.