[1] Univ Iowa, Coll Publ Hlth, Ctr Emerging Infect Dis, Dept Epidemiol, Iowa City, IA 52242 USA
[2] Ctr Dis Control & Prevent, Resp & Enter Viruses Branch, Atlanta, GA 30333 USA
[3] Univ Iowa, Coll Publ Hlth, Hosp Informat Syst, Iowa City, IA 52242 USA
[4] CHU Laval, Chuq, Lab Infectiol, Quebec City, PQ G1V 4G2, Canada
[5] Univ Iowa, Hosp & Clin, Iowa City, IA 52242 USA