Pertussis: No Longer “Whooping” But Still a Serious Public Health Problem

My generation as a resident (1974 to 1977) was rife with rheumatic heart disease. As a result, I was attuned to mitral stenosis because I heard it over and over. Next, we learned about treating beta-hemolytic Streptococcus infection, and the disease was dealt a blow.

Today, residents have no reference point for that telltale diastolic rumble. Conversely, even then, vaccination had all but eradicated pertussis, a disease many recent generations are not familiar with. It was an infant’s disease that we fixed.

Two things have unfortunately changed in recent years: pertussis is reemerging and a lapse in vaccination practices is responsible. Recent articles focus attention on this important “contemporary” disease.^1,2

The year 2009 should serve as a wake-up call. It experienced 16,858 cases of pertussis, including 12 reported deaths.¹ Although heightened awareness, increased reporting, and an innovation in diagnosis (polymerase chain reaction [PCR] testing) helped, waning immunity obtained from an infant/child vaccination series became a serious problem.¹ That is why as many as 50% of those infected with Bordetella pertussis are adolescents and adults—who can then infect infants.

CLINICAL CLUES TO PERTUSSIS

The disease itself begins with a “catarrhal” phase that is nonspecific (malaise, rhinorrhea, and cough).¹ Look for subtle signs such as excessive lacrimation and conjunctival injection as earlier signals (before the cough) to the presence of pertussis.¹ The cough follows and can last as long as 48 days.¹ Today’s adults do not “whoop.”¹ Another clinical pearl is the presence of “posttussive emesis.”¹ Can the cough be forceful? It has actually led to carotid artery dissection.¹

DIAGNOSTIC TOOLS

Definitive diagnostic tools are available if strong diagnostic suspicion exists.¹ If the catarrhal stage is present, order PCR plus culture. The coughing or paroxysmal stage uses PCR (unlikely to be positive after 1 month of infection) and serology. During convalescence, serology is the test of choice (a 2-fold increase in titer or without an acute-phase sample, a single elevated titer is acceptable).

FIRST-LINE THERAPY

The antibiotic of choice for pertussis is azithromycin.¹ But there is more to the antibiotic story. Antibiotic use does not alter symptoms even with eradication of the organism.¹ This is especially true 2 weeks or more after the infection begins.

STRATEGY FOR PREVENTION

Although primary care physicians should be aware that incidence of pertussis is increasing; that it is now also a disease of adolescents and adults; specifics regarding its clinical and laboratory diagnosis; and the antibiotic facts enumerated above, wouldn’t it be better to prevent it if we could? Since we are the gatekeepers of vaccination administration, there is a way.

The first article¹ and a second² offer sound advice in this regard. The current and most up-to-date recommendation for Tdap (tetanus, diphtheria, and pertussis) boosters is to substitute a 1-time dose for the typically redundant (every 10 years) Td booster. This way, the waning immunity for B pertussis will be boosted in infection-prone adolescents and adults, the new reservoir for this nasty little bacterium. We are in a unique position to prevent as well as diagnose this resurgent disease.