Clinical Impression Remains Most Accurate Predictor of Whooping Cough

When it comes to diagnosing whooping cough, a physician’s gut impression is still the most accurate predictor of infection, according to a new study from researchers at the University of Georgia.

Whooping cough, also known by its clinical name pertussis, is caused by Bordetella pertussis (BP) bacteria. The disease has seen a resurgence in the past few years despite there being a vaccine to prevent its spread.

In fact, the increasing number of pertussis outbreaks is what motivated Dr. Mark Ebell to perform an updated systematic review of the signs of symptoms of pertussis for infants, children, and adults in the hopes of helping primary care physicians better identify patients who may need to be tested for pertussis.

Dr. Ebell is a professor of epidemiology at UGA’s College of Public Health and lead author on the study, which appeared in the Journal of the American Board of Family Medicine in May.

This review follows a meta-analysis which looked at the prevalence of pertussis that Dr. Ebell completed in 2016. “It turned out it’s actually more common than most people would think,” he said. In primary care patients with a prolonged cough, 12 percent of adults and 18 percent of children were infected with BP.

“The problem with the increasing incidence is simply people aren’t getting vaccinated,” said Dr. Ebell. The national vaccination rate for the full series of pertussis vaccinations has dropped to 84 percent, as pockets of parents across the U.S. are choosing to not vaccinate their children.

Early symptoms of pertussis are relatively mild, but as the illness advances, the severe, tell-tale “whooping” cough can make breathing difficult and even cause vomiting. These symptoms can prove deadly for babies and young children, due to their smaller airways.

Whooping cough can be treated using antibiotics, but the treatment is most effective when started within one to two weeks of the onset of symptoms.

“The trouble with pertussis is it kind of looks like a typical viral cough for the first week,” said Dr. Ebell. “By the time it starts to look more like pertussis, it’s often too late for the treatment to have much effect, and it may have been spread to a lot of other people.”

And unfortunately, none of the individual signs and symptoms Dr. Ebell and his co-authors assessed were good indicators of BP infection. The strongest predictor turned out to be the physician’s overall impression.

An experienced clinician who has seen hundreds and hundreds of people coughing, says Dr. Ebell, can usually tell if a patient with a cough may have pertussis. “They are evaluating multiple signs and symptoms at once, making that a better predictor than individual factors.”

Future research should look for specific combinations of signs and symptoms that may more accurately diagnose pertussis, says Dr. Ebell. He also believes this and his previous study are at least putting pertussis back on the radar for primary care providers.

“It’s not common, but it’s not zero, either,” said Dr. Ebell. “If someone that’s been coughing for more than a week, and has some of the typical symptoms like a whoop, spasms of cough or vomiting after coughing, then you should start thinking about the possibility of pertussis as cause.”

Mr. Christian Marchello and Ms. Maria Callahan, both epidemiology graduate students at UGA’s College of Public, co-authored the study. The paper, “Clinical Diagnosis of Bordetella Pertussis Infection: A Systematic Review” is available here: http://www.jabfm.org/content/30/3/308.full.pdf