ATLANTA – Infants with more-severe pertussis infections are more likely to have higher white blood cell counts and more-rapid increases in those counts than are infants with less-severe infections, according to findings from a California study of 31 infants.
These 31 infants, aged 90 days or younger, were admitted to the pediatric ICU at one of five participating centers in California following a 2010 Bordetella pertussis epidemic in the state, during which 10 infants died from the infection. The findings have implications for identifying infants with potentially severe infections early in the course of their illness, to allow for more rapid implementation of interventions such as exchange transfusion that may improve outcomes, Dr. James D. Cherry reported at the International Conference on Emerging Infectious Diseases.
Of the 31 infants who were admitted between September 1, 2009, and June 30, 2011, at a median age of 36 days, 8 had more-severe infections (defined by the presence of pulmonary hypertension or by infection-related mortality). Seven had pulmonary hypertension, and four of the eight infants died.
©CDC
A photomicrograph of Bordetella pertussis bacteria.
Compared with the 23 infants who had less-severe infections, the 8 with more-severe infections had significantly higher peak WBC counts (72.8 vs. 26.3 x 103/mcL), their WBC count exceeded 30.0 more rapidly following onset of illness (5.1 vs. 14.6 days), and they were more likely to have a 50% increase in their WBC count within 24 hours of illness onset (50% vs. 0%), said Dr. Cherry, a pediatric infectious disease specialist with Mattel Children’s Hospital at the University of California, Los Angeles.
Those with more severe infection also were significantly more likely to receive an exchange transfusion (75% vs. 0%), to be diagnosed with pneumonia (100% vs. 43%), and to be intubated (75% vs. 9%), he noted.
The more-severe and less-severe patient groups were similar with respect to sex, ethnicity, and median age at onset. Overall, 54% were girls and 94% were Hispanic.
This study is unique in that all patients in the pediatric ICU were younger than 3 months of age, Dr. Cherry said, noting that based on earlier data, it was assumed that this differences in outcomes among infants with pertussis was associated with delays in getting appropriate care.
"But after seeing [these new] data, I think it’s a lot more complicated than that," he said, explaining that no differences were seen between the groups in demographic factors that are health care indicators.
The findings suggest that it is imperative in these very young babies to assess WBC immediately so the trajectory can be tracked. Those at risk for a more-severe course should be considered for exchange transfusion, he concluded.
Dr. Cherry said he had no relevant financial disclosures.