Caution: The Whooping Cough Is Back

May 2009

By Mitchell B. Cordover
ACEP News Contributing Writer

This article was underwritten by an unrestricted educational grant by Sanofi Pastuer, ACEP’s Official Wellness Supporter.

When we think of emergency physician wellness, the threat of infectious disease does not immediately come to mind. Most of us are reassured that universal precautions and the recent innovations in safety needles will protect us from the usual suspects. Most of us are immunized against hepatitis B and tested yearly for the rare case of tuberculosis.

But what if there was an infectious disease spread by respiratory droplets, was increasing logarithmically in the community, and had a transmission rate as high as 90%? What if it took 8-10 weeks to recover from the disease, which has a 15%-30% complication rate? The average victim would lose a week of work or more.

Now consider that, if you brought it home to your kids, there would be a 25% incidence of secondary pneumonia for toddlers and a significant rate of death for infants.

We are talking about pertussis--and it's back with a vengeance.

At its height in the 1930s-1940s, pertussis was reported in 250,000 Americans during its 3- to 5-year epidemic cycle. This was probably significantly underreported. In that preantibiotic era, it was feared as the "whooping cough," and its mortality rate made it one of the great scourges of children.

When the pertussis vaccine came into use in the 1940s, the incidence dropped to less than 1 case per 100,000 people. Because humans are the only known reservoir of the disease, public heath officials talked about having conquered it.

As time passed, however, the immunity conferred by the vaccine proved to last only 5-10 years. Booster shots for adolescents and adults were not considered feasible on a wide scale, because the reactions to the original viral vaccine (and even to the subsequent acellular vaccine) were too common and bothersome.

By 2002, there were more than 25,000 reported cases of pertussis, and officials with the Centers for Disease Control and Prevention (CDC) believe the underreporting level was 90%-95%.

By 2006, the incident rate rose to 5.2 reported cases per 100,000 people, and probably twice that, in reality. That's a 5- to 10-fold increase. Eight cases in 10 are in adolescents and adults--including emergency physicians. It is the only vaccine-preventable disease currently on the rise.

The real risk to emergency physicians and their families is that the first week of pertussis looks like any viral syndrome and is misdiagnosed as such. But the Bordetella pertussis bacteria are transmitted during this stage, as well as in the subsequent stages. By the time a patient comes in complaining of a month of cough, we already have what we believe is their cold.

Depending on the study, between 15% and 52% of adults with a cough lasting more than 14 days have pertussis. For infants younger than 2 months or those who have incomplete vaccinations, the risk of catching this disease from emergency physicians is very real. In one study, when a source of pertussis was identified in a child, the parents or siblings were the culprit 75% of the time.

Luckily, in 2005, an adult version of the acellular pertussis vaccine was licensed. It has a lower dose of pertussis vaccine, so it confers a protective level of immunity with an acceptable level of side effects. The vaccine is combined with diphtheria and tetanus, and the combination is called Tdap.

The CDC's Advisory Committee on Immunization Practices has recommended that Tdap replace Td for routine immunizations. All children should get Tdap at age 11- 12 years; any 18-year-old patient who was not immunized at that age should get a Tdap booster.

All nonpregnant adults younger than 65 years who have not had a Td in 5 years should get immunized now. This is especially true for health care providers.

Emergency physicians can safely get a booster as often as every 2 years, or even sooner under special circumstances. While pregnancy and nursing are not contraindications to vaccination, the CDC recommends postponing Tdap until after delivery.

There are contraindications to the vaccine, including prior fever of 105º F or higher with previous vaccinations, prior vaccine-related Guillain-Barré syndrome, CNS disease, Arthus reaction to tetanus vaccine, and other signs of allergy or intolerance.

Compared with other challenges to physician health, avoiding pertussis is relatively easy. If you have not had a recent Td, get immunized. Many EDs offer the shot free of charge, and it will protect you, your patients, and your family.

Dr. Cordover is chair of ACEP's Well-Being Committee and Councillor for ACEP's Wellness Section.

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