EPIDEMIOLOGY AND COST OF INFECTION WITH HUMAN PARAINFLUENZA VIRUS TYPE-1 AND TYPE-2 IN YOUNG-CHILDREN

To determine the morbidity, costs, and epidemiological features of low er respiratory tract infections (LRIs) due to human parainfluenza viru s types 1 and 2 (HPIV-1 and HPIV-2), we evaluated 1,213 children < 6 y ears of age who were seen for LRIs in the emergency room of the Childr en's Hospital of Wisconsin and/or were admitted to the hospital for LR Is during the fall quarter of 1991. The age, sex, race, and respirator y syndrome were recorded for each child; 158 patients (13%) had respir atory samples cultured for viruses and were followed clinically for th e duration of their illness. Caucasian children had croup diagnosed mo re often than did African-American children (relative risk [RR] = 3.12 ; 95% confidence interval [CI], 2.43-4.00; P < .001), while African-Am erican children more often had pneumonia (RR = 1.85; 95% CI, 1.36-2.5; P < .001). Forty-five of 70 viruses recovered were HPIV-1 (17 cases) or HPIV-2 (28 cases). Together these two viruses were recovered from 4 9% of children presenting with croup, 10% of those presenting with bro nchiolitis, and 12% of those presenting with pneumonia. Gender- and ra ce-associated differences were documented in the group of children inf ected with HPIV-2: specifically, this group included more girls than b oys (RR = 1.99; 95% CI, 1.02-3.88; P < .04) and more Caucasian than Af rican-American children (RR = 2.64; 95% CI, 1.05-6.63; P = .027). Thes e data extrapolate nationally to similar to 250,000 emergency-room vis its and similar to 70,000 hospitalizations due to HPIV-1 and HPIV-2, w ith a cost of $50 million for the former and $140 million for the latt er.