Epidemiological aspects of canine leptospirosis in the Netherlands.

The epidemiology of canine leptospirosis has been examined in a limited study in the Netherlands from 1969 through 1982. Leptospira interrogans serotype icterohaemorrhagiae and canicola were found to be the only serotypes causing clinical leptospirosis. However, positive agglutination titres to the serotypes grippotyphosa, bratislava, poi and ballum have also been detected. The incidence of infection caused by serotype icterohaemorrhagiae was highest during summer and autumn. Infections with serotype canicola were more evenly distributed over the year with only a slight increase during summer and autumn. Infections caused by serotype canicola were significantly more prevalent in male dogs, whereas infections with serotype icterohaemorrhagiae were found both in males and females in almost equal numbers. The incidence of infections with serotype icterohaemorrhagiae was highest in immature dogs. Infections with serotype canicola were detected in young as well as older animals. In contrast to the situation in the past, infections with serotype icterohaemorrhagiae are now more common than those caused by serotype canicola, which have become rare. The highest incidence of infection was found in the western part of the country. The majority of infections was demonstrated in guard-dogs and sporting-dogs. Dogs proved to be of minor importance as a source of human infection in the Netherlands.