Doris Dimmitt, Carson Tahoe Health Epidemiologist

Pertussis? What do you mean there is a pertussis epidemic in California? Weren’t we all vaccinated as kids for pertussis? What the heck is going on?

I am happy to talk about pertussis and what it means today. First of all, yes, pertussis is back, and California is having a difficult time with it right now. There have been almost 1000 confirmed cases, over 600 cases under investigation and five infant deaths in our neighbor to the west, so far, this year. Yes, we were vaccinated as kids, but pertussis is the most poorly controlled vaccine preventable disease on the planet. The incidence has been increasing every year since the 1990s. This infection appears every 2-5 years with the last peak in 2005. The infection is not restricted to kids by any means. Adult infections accounted for 27% of the pertussis cases in the U.S. Pertussis vaccine protection decreases to almost nothing in 10-15 years without a booster shot.

The symptoms in adults are a whooping breath between coughs, hence the name whooping cough. Once you have heard the cough of a pertussis patient you are not likely to ever forget it. The coughing comes on in a spasm making it difficult to catch your breath, and the spells can be severe enough to cause vomiting (sounds like fun doesn’t it?). There is usually no fever, no body aches, and no sign of a systemic infection like the flu. There may be a runny nose and sweating episodes. Adults with pertussis often report feeling as if they’re chocking on something. The symptoms can last up to 6 weeks (UGH) with an incubation period of 6-20 days, and adults almost always recover. Infants are not so lucky. Pertussis symptoms in a baby begin looking deceptively like a common cold. Coughing may or may not be present. This can quickly change to apneic episodes, seizures, respiratory distress and pneumonia. All the deaths in California from pertussis this year have been infants less than 3 months old.

So why is it back? Pertussis is caused by a bacterium called Bordetella pertussis. I won’t bore you with any more of the microbiology stuff now. One theory for the whooping cough problem is possible genetic changes in the germ making it more dangerous than it was 50 years ago. This could be one of those nasty bacteria things getting nastier, (there’s a lot of that going around these days). Another idea is vaccine immunity has worn off making more of us susceptible to the infection. Vaccine boosters (Tdap) for middle school kids are not required in all states, including California. FYI, Nevada does require a booster vaccine for middle school. More parents opting to not vaccinate their children out of fear of side effects doesn’t help either. We must also keep in mind more pertussis is diagnosed today as physicians are more aware and there are better laboratory tests to detect cases that probably went undiagnosed in the past. What ever the reason(s), it is back and we must deal with it.

Pertussis is very contagious with as much as a 90% transmission rate among close contacts. This means if 10 people are exposed, 9 will catch pertussis. That is pretty darn impressive, as most infections are not nearly that easy to catch. Most cases in adults will never be diagnosed because the symptoms can be mild. The problem is the infants. Adults and older children spread pertussis to the babies, and this is serious. To protect the babies, we use a technique called “cocooning”. This simply means vaccinating everyone having contact with little babies so the babies are not exposed to the disease. Picture a cocoon protecting a baby from harm. Currently, our Obstetrics and Pediatric units offer the pertussis vaccine to all new parents for this reason. This is also called “herd immunity”.

If most of the “herd” is immune to an infection, the susceptible members are more protected. Since the little bitty ones are not fully vaccinated, this is the best way to keep them safe from pertussis. So the main message in this memo is, if you are pregnant, your spouse is pregnant, you have an infant in your home, or have close contact with infants, get a pertussis vaccine ASAP. The babies are depending on us. Please comment if you have any questions.