A study published in the Jan. 10 online Journal of the Pediatric Infectious Disease Society (JPIDS) reports that taking early and repeated white blood cell counts is critical to diagnosing pertussis – also known as whooping cough — in infants. According to the study, such tests are also reliable indicators of which infants have the highest risk of dying from respiratory infection.
Infants at greatest risk
Pertussis is a highly contagious bacterial infection of the respiratory tract. As reported in a JPDIS news release, most children are vaccinated against pertussis at an early age, but infants are too young to complete the vaccination series.
The U.S. Centers for Disease Control and Prevention (CDC) reports that the 2012 rates of the disease were at their highest level in 50 years. More than 41,000 cases of pertussis were reported across the U.S., including 18 deaths. The majority of deaths continue to occur among infants younger than 3 months of age.
Researchers examined the medical records of 31 infants admitted to five pediatric intensive care units in California between September 2009 and June 2011. California reported its highest pertussis rate in 60 years in 2010.
The study showed that infants that had the most severe cases of the disease had the highest white blood cell counts (WBC). Infants with less severe cases of whooping cough had median peak counts of about 24,000 compared with about 74,000 among the infants with more severe cases.
In addition, infants with severe cases were more likely to show a 50 percent increase in white blood cell counts within 48 hours. Researchers also found that infants in this group were more likely to have higher maximum heart and breathing rates and were more likely to develop pneumonia.
All of these conditions occurred earlier after the onset of the illness among infants with more severe cases of pertussis. Infants in this group were more likely to experience shock, seizures, and renal failure, and to require transfusions. Four infants in the severe-case group died.
“Because very young infants have not yet been vaccinated and are at the highest risk for severe disease, we need to better manage and treat it,” said Erin Murray, lead author of the study and an epidemiologist at the California Department of Public Health, in the JPDIS news release.
“This study shows the importance of aggressive pediatric intensive care and provides us additional metrics as we treat these very young patients,” added Murray.