Prevention of a severe disease by a Leptospira vaccination with a multivalent vaccine

Leptospirosis is a worldwide zoonosis caused by Leptospira interrogans which include all pathogenic strains of the Genus Leptospira. The serological classification of the members of Leptospira interrogans distinguishes more than 200 serovars which have traditionally been grouped into serogroups according to their antigenic relation [16]. After natural infection with Leptospira, the spectrum of infection in the dog ranges from acute to subacute or chronic [18]. These clinical forms are influenced by virulence factors, the immune status of the dog and the host adaptation (i.e. primary reservoir host or incidental host) [11]. The disease in primary reservoir hosts tends to be more chronic or asymptomatic with weak antibody responses. In contrast, the disease in incidental hosts tends to be acute and severe with marked antibody responses [18]. The common clinical signs expected in dogs include hypothermia, pyrexia, depression, anorexia, vomiting, abdominal pain, icterus, congestion of ocular mucosa, diarrhoea [13, 7, 1]. Historically, the serovars associated with clinical disease in the dog included L. canicola and L. icterohaemorrhagiae [10, 7, 18]. Therefore vaccines currently used in dogs in most countries contain inactivated whole Leptospira belonging to serogroups Canicola and Icterohaemorrhagiae [16, 18].