WBC quantifies risk of death from pertussis

A retrospective study of infants hospitalized with pertussis showed that the babies who had more severe disease had much higher white blood cell (WBC) counts and experienced rapid jumps in WBCs after onset of the illness compared with babies who had less severe infections.

Researchers analyzed medical records of 31 infants aged 3 months and younger who were hospitalized for pertussis in 5 pediatric intensive care units in Southern California during the pertussis outbreak between September 2009 and June 2011. Eight infants were described as having severe pertussis, which included suffering from pulmonary hypertension and death.

The infants with severe pertussis had higher WBCs than the 23 infants with less severe illness: median peak WBC of 74,100 compared with 24,200, respectively. Seven of the 8 babies with severe pertussis also showed a 50% increase in WBC within 48 hours of disease onset, whereas none of the infants with less severe pertussis had more than a 50% increase in WBC.

In addition, infants with more severe infections had higher heart rates (exceeding 170 beats per minute) and respiratory rates (exceeding 70 breaths per minute after onset of cough) compared with infants with less severe illness. The group with severe infection also was more likely to progress sooner to pneumonia, seizures, shock, renal failure, intubation, and exchange transfusions. Four of these infants died.

The researchers hope that using their metrics to identify whether infants have pertussis and which children are at highest risk of death will enable physicians to implement aggressive interventions to better manage and treat the disease.

Pertussis cases totaled 1,270 for 2012, according to data from the Centers for Disease Control and Prevention, and by January 5 this year, new cases already numbered 41.

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