[1] Univ Ferrara, Sect Microbiol & Med Genet, Dept Med Sci, I-44100 Ferrara, Italy
[2] Univ Hosp St Orsola Malpighi, Operat Unit Clin Microbiol, Virol Lab, Bologna, Italy
[3] Univ Hosp St Orsola Malpighi, Operat Unit Obstet & Prenatal Med, Bologna, Italy
[4] Univ Hosp St Orsola Malpighi, Operat Unit Prevent Paediat & Neonatol, Bologna, Italy