West Nile in the Mediterranean Basin: 1950-2000


Address for correspondence: Bernadette Murgue, M.D., Ph.D., CNR des Arbovirus et des Fièvres hémorragiques virales, Institut Pasteur, 25, rue du Dr-Roux, F-75724 Paris cedex 15 France. Voice: +33-(0)1 40 61 38 87; fax: +33-(0)1 40 61 31 51; bmurgue@pasteur.fr.


Abstract: Recent West Nile virus (WNV) outbreaks have occurred in the Mediterranean basin. In Algeria in 1994, about 50 human cases of WN encephalitis were suspected, including 8 fatal cases. In Morocco in 1996, 94 equines were affected of which 42 died. In Tunisia in 1997, 173 patients were hospitalized for encephalitis or meningoencephalitis. West Nile serology performed on 129 patients was positive in 111 cases (87%) including 5 fatal cases. In Italy in 1998, 14 horses located in Tuscany were laboratory confirmed for WNV infection; 6 animals died. In Israel in 1998, serum samples from horses suffering from encephalomyelitis had WNV antibodies and virus was isolated from the brain of a stork; in 1999 WNV was identified in commercial geese flocks, and in 2000 hundreds of human cases have been reported. In September 2000, WNV infection was detected in horses located in southern France, close to the Camargue National Park where a WNV outbreak occurred in 1962. By November 30, 76 cases were laboratory confirmed among 131 equines presenting with neurological disorders. No human case has been laboratory confirmed among clinically suspect patients. The virus isolated from a brain biopsy is closely related to the Morocco-1996 and Italy-1998 isolates from horses, to the Senegal-1993 and Kenya-1998 isolates from mosquitoes, and to the human isolate from Volgograd-1999. It is distinguishable from the group including the Israel-1998 and New York-1999 isolates, as well as the Tunisia-1997 human isolate.