Abstract
BACKGROUND: Influenza has been a major source of morbidity and mortality worldwide. Children are one of the most susceptible groups for severe influenza. Clinical differentiation between viral and bacterial pneumonia is difficult to assess in children, so the aid of the complete blood count (CBC) and C-reactive protein (CRP) are used to differentiate between them. However, differential diagnosis between influenza-positive and -negative viral pneumonia is difficult. CRP levels have been found to be higher in H1N1 influenza adult patients. However, there are no studies regarding CBC, and CRP levels in pediatric patients with influenza-positive and -negative pneumonia. METHODS: From 2011 to 2016, we found children less than 18 years old with viral pneumonia who had positive viral RT–PCR test for adenovirus, bocavirus, influenza, parainfluenza, metapneumovirus, rhinovirus, coronavirus or respiratory syncytial virus (RSV). Means for white blood cells (WBC), neutrophils, lymphocytes and CRP were calculated. Comparisons between influenza and other respiratory viral pneumonia WBC and CRP means were made. Student’s t-test was used for statistical analysis. RESULTS: We analyzed 183 patients with positive viral pneumonia cases; of which, 37 (20.2%) had two viruses detected. Mean age was 1 year old and 56.5% were male. Viral detections were rhinovirus 75 (40.9%), RSV 45 (24.5%), influenza 31 (16.9%), metapneumovirus 30 (16.3%), bocavirus 20 (10.9%), parainfluenza 14 (7.6%), coronavirus 3 (1.6%) and adenovirus 2 (1.1%). Mean influenza WBC were 10,900 ± 2040/μL, neutrophils were 6998 ± 1510/μL, lymphocytes 2882 ± 826/μL and CRP 5.41 ± 1.9 mg/dL. Mean influenza negative, viral-positive pneumonia were WBC 12227 ± 868/μL, neutrophils 6787 ± 696/μL, lymphocytes 4469 ± 426/μL, CRP 2.81 ± 0.56 mg/dL. Lower lymphocyte counts (P = 0.002) and higher CRP levels (P = 0.019) were found in patients with influenza comparing them with pneumonia caused by other viruses. CONCLUSIONS: In our study, children with positive influenza pneumonia showed lower levels of lymphocytes and higher levels of CRP compared with negative influenza. Lower lymphocyte counts and high CRP levels have been found in influenza-positive patients mainly in adult studies. In children with suspected influenza pneumonia, lower lymphocyte counts and higher CRP levels can aid clinical diagnosis before molecular confirmation in influenza pneumonia.