[1] Childrens Hosp, Westmead, NSW 2145, Australia
[2] Univ Sydney, Discipline Paediat & Child Hlth, Sydney, NSW 2006, Australia
[3] Univ Sydney, Sydney Sch Publ Hlth, Screening & Test Evaluat Program, Sydney, NSW 2006, Australia
[4] Victorian Cytol Serv, Melbourne, Australia
[5] Royal Hosp Women, Dept Microbiol & Infect Dis, Melbourne, Vic, Australia