Introduction: Four infant deaths in one year due to pertussis at our hospital prompted a retrospective chart review to determine the trends in pertussis hospitalizations in children < one year of age over the past 14 years.
Methods: All medical records from July 1988-June 2002 with pertussis-specific ICD-9 codes were reviewed. Subjects were included in the analysis if they were < one year of age, had positive pertussis tests, an epidemiological link to a laboratory-confirmed case; or if they had cough > two weeks with paroxysms, inspiratory whoops or post-tussive vomiting. Demographic, clinical, laboratory, and hospital course data were collected.
Results: Of the 85 patients identified, 69 subjects met the inclusion criteria. Cases increased over the years with two cases detected from 1988-92, 22 from 1993-97, and 45 from 1998-2002 (p < 0.001). Mean age at admission was 71 days; 94 percent were < six mos. compared to children between six mos.-one yr. (p < 0.001). Mean birth weight was 3027g, with 17 percent preterm. Most subjects (77 percent) had no pertussis immunizations. Presenting symptoms were paroxysmal cough 85 percent, cyanosis 68 percent, and apnea 52 percent. Oxygen was required in 35 percent, mechanical ventilation in 12 percent, and extracorporeal membrane oxygenation (ECMO) in four percent because of uncontrolled pulmonary hypertension. All three subjects on ECMO died. Mean lymphocyte count was 46.3 thou/uL in survivors and 61.1 thou/uL in those who died (p = 0.001).
Conclusions: The number of patients hospitalized with pertussis has significantly increased. Mortality was seen in infants < 3 mos. with pulmonary hypertension, pneumonia, and elevated lymphocyte counts. These data support the need for new immunization strategies to prevent pertussis disease in infants too young to have been immunized.