WHITE BLOOD-CELL AND DIFFERENTIAL COUNTS IN ACUTE RESPIRATORY VIRAL AND BACTERIAL-INFECTIONS IN CHILDREN

White blood cell (WBC) and differential counts were studied in 201 chi ldren hospitalized for acute viral or bacterial respiratory infection. The aetiology of infection was studied with a comprehensive set of se rological tests. WBC and granulocyte counts were higher in patients wi th bacterial infection than in those with viral infection. Lymphocyte counts, by contrast, had no such aetiological association. The 95% con fidence limits for WBCs and granulocytes distinguished bacterial and p neumococcal cases completely from viral cases with no bacterial involv ement. The sensitivity of WBC counts, as well as granulocyte or lympho cytes counts, for distinguishing bacterial from viral cases was low at all cut-off levels. Specificity, in contrast, was 86% and 95% for WBC s at the cut-off levels 15.0 and 20.0 X 10(9)/l, and 84% and 97% for g ranulocytes at the cut-off levels 10.0 and 15.0 x 10(9)/l, respectivel y. It is concluded that high WBC and granulocyte counts are clear evid ence of the bacterial aetiology of respiratory infection, but low or n ormal values do not rule it out. Lymphocyte counts are of no value for distinguishing between viral and bacterial infections.