INCUBATION PERIODS OF EXPERIMENTAL RHINOVIRUS INFECTION AND ILLNESS

Eleven young adults with experimental rhinovirus infection (cases) and six noninfected saline-challenged young adults (controls) underwent n asal washings and symptom evaluations at 2-hour intervals for 24 hours after intranasal challenge. The mean and median periods to the first recovery of virus were 11.3 hours and 10 hours, respectively. Geometri c mean rhinovirus titers in cases reached 10(0.2) log(10) TCID50 (50% tissue culture infective dose)/0.1 mL at 10 hours and rose to 10(1.0) log(10) TCID50/0.1 mL at 18 hours. Nine (82%) of 11 cases and one (16. 7%) of six controls had colds. Mean total symptom scores for cases bec ame significantly higher than those for controls at 16 hours. Sore or scratchy throat appeared between 10 and 12 hours in cases, but nasal o bstruction and rhinorrhea first appeared at 2 hours, thus suggesting s ome nasal irritation from the viral inoculum pool. The incubation peri od for experimental rhinovirus infection is similar to that in cell cu lture. Nasal and pharyngeal symptoms began early in infection.