West Nile virus (WNV) has re-emerged in Italy, resulting in 28 equine clinical cases, including seven deaths as of last week, according to an epidemiological bulletin produced by the Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "Giuseppe Caporale" (IZSA&M), an Italian public health institute.
The epidemic began in central eastern Italy in August, in the same location as a 2008 epidemic which caused 32 clinical cases and five deaths in horses. Prior to that outbreak, Italy had been free of West Nile virus since a 1998 outbreak in Tuscany.
"Very preliminary data suggest that the virus was able to overwinter," said Federica Monaco, PhD, researcher at the IZSA&M and primary author of a recently published scientific paper on the 2008 epidemic. "It's likely that the virus cycle did not stop during the cold months, but we still lack sufficient data to define which hosts (mosquitoes, birds, etc.) are involved."
So far the virus has shown no signs of spreading to other regions, Monaco said. Vaccines have been made available to horse owners, but they are not mandatory at this time.
Although it's been circulating in the United States and Canada since 1999, WNV is relatively rare in Europe, with the previous last known case occurring in France in 2003.
The paper, "Re-Emergence of West Nile Virus in Italy," was published in the journal Zoonoses and Public Health in July 2009. The abstract is available on PubMed.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.