Abstract & Commentary

Pertussis in Infants in California

By Dean L. Winslow, MD, FACP, FIDSA, Chief, Division of AIDS Medicine, Santa Clara Valley Medical Center; Clinical Professor, Stanford University School of Medicine; is Associate Editor for Infectious Disease Alert.

Dr. Winslow is a speaker for Cubist Pharmaceuticals and GSK, and is a consultant for Siemens Diagnostics.

Synopsis: A total of 32 infants younger than age 3 months with pertussis were hospitalized at Children's Hospital of Orange, CA (CHOC). Compared to infants hospitalized with viral respiratory infections, patients with pertussis were more often afebrile, had more visits before admission, and had longer hospital stays.

Source: Nieves DJ, et al. Clinical and laboratory features of pertussis in infants at the onset of a California outbreak. J Pediatrics 2011; Epub ahead of print.

A total of 32 infants younger than age 3 months with pertussis hospitalized at a large children's hospital in Southern California were compared to 92 control patients hospitalized with RSV or influenza virus infections. Of the infants hospitalized with pertussis, 81% were Hispanic, 16% were white, and 1 infant was Vietnamese. PCR was positive in 27 of 27 patients studied with this diagnostic method, 20 of 28 were positive by culture, and 3 of 3 were positive by DFA.

Admission at first outpatient visit for the acute illness occurred in 27% of pertussis patients and in 53% of controls. Seven pertussis patients had three or more outpatient visits prior to hospital admission compared to no control patients. Pertussis patients had a longer duration of symptoms prior to admission vs. control patients (mean, 11 days vs. 3.4 days, respectively) and were also less likely to have fever or congestion than the controls. Paroxysmal coughing, post-tussive emesis, and apnea or seizure were also more likely in the pertussis patients than in controls. Mean WBC and absolute lymphocyte count were higher in pertussis patients. Average length of hospital stay was significantly longer in pertussis patients than in controls (mean, 8.9 days vs. 3.5 days, respectively). PICU admission was more common in the pertussis patients. Household coughing contacts were reported for 75% of pertussis patients and 71% of the pertussis patients had not received pertussis immunization.

Commentary

This is an important large case series, which highlights some of the clinical features of infants with pertussis who were ill enough to require hospitalization. Despite the fact that pertussis became epidemic in California in 2010, it is clear that many pediatricians/primary care practitioners did not think of this diagnosis when first seeing a sick infant with paroxysmal cough. It is also likely that the frequent absence of fever in younger children with pertussis contributed to delayed diagnosis. Unrecognized pertussis in adult and adolescent household contacts of these infants was the source of infection in virtually all cases.

"Cocoon" vaccination of household contacts of infants too young to receive pertussis immunization is critically important as a control strategy for prevention of this severe disease. This should include state-mandated Tdap prior to middle school entry, administration of Tdap to pregnant women, and aggressive administration of this vaccine to virtually all adults and adolescents. Successful implementation of these measures will require ongoing education efforts directed to both patients and health care providers.