West Nile virus transmission in 2008 in north-eastern Italy.

After 10 years, West Nile virus (WNV) re-emerged in Italy in August 2008. As on 31 December 2008, the infection affected eight Provinces in three Regions (Emilia Romagna, Veneto, Lombardy), where a total of 794 cases of WNV infection in 251 equine stables were detected on the basis of the clinical signs and as a result of a serological screening in horses living in the area. Only 4.0% (32/794) of the serologically positive animals showed clinical signs, and the 32 clinical cases were reported in 18 different farms. The observed case-fatality rate was 15.6% (5/32). The confirmed clinical cases were detected from end August to mid October. Significant levels of positivity by RT-PCR were also observed in magpies (Pica pica) (9.1%, 95% confidence levels: 6.1-13.4%), carrion crows (Corvus corone) (7.4%, 95% confidence levels: 3.6-14.4%) and rock pigeons (Columba livia) (12.9%, 95% confidence levels: 7.6-21.2%).