Decreased leukocytes and other characteristics of laboratory findings of influenza virus infections in children.
OBJECTIVE
An outbreak of influenza A and influenza B appeared at the beginning and end of 2006 in southern Taiwan. We conducted this study to test whether laboratory findings could differentiate influenza A from influenza B infection.


METHODS
All children aged 16 years or less, who had nasal and/or throat swabs sent from inpatient or outpatient settings at National Cheng Kung University Hospital for the diagnosis of influenza infection from January 2005 to February 2007, were considered eligible subjects. Retrospective chart review of clinical and laboratory data was performed.


RESULTS
274 patients were enrolled, 151 with influenza A and 123 with influenza B, of whom 127 (46.4%) received laboratory examinations. The peak month of influenza A and influenza B infections was January 2006 and January 2007, respectively. Children with influenza B infections were older than those with influenza A infections (p<0.001). Influenza B-infected patients were more likely to have myalgia (p=0.004) than those with influenza A infections. Furthermore, children with influenza B infections tended to have lower leukocyte counts (6383 +/- 3970/mm3 vs 7639 +/- 3476/mm3, p=0.004), and higher serum creatine kinase level (p=0.002) than those with influenza A infections. The clinical outcomes were usually favorable.


CONCLUSIONS
The clinical features of influenza B and influenza A infections are similar. However, decreased leukocytes and increased serum creatine kinase can be used as adjunctive criteria for diagnosis of influenza B infection before viral culture results are available.
Shen
Ching-Fen
CF
Department of Pediatrics, National Cheng Kung University Medical College and Hospital, Tainan, Taiwan.
Huang
Shu-Ching
SC
Wang
Shih-Min
SM
Wang
Jen-Ren
JR
Liu
Ching-Chuan
CC
D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D003402:Creatine Kinase / Q000097:blood; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D009980:Influenza A virus / Q000302:isolation & purification*; D009981:Influenza B virus / Q000302:isolation & purification*; D007251:Influenza, Human / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology; D007958:Leukocyte Count; D008297:Male; D018709:Statistics, Nonparametric; D013624:Taiwan / Q000453:epidemiology; D014776:Virus Cultivation
D003402:Creatine Kinase