Infection caused by Leptospira interrogans is an important zoonotic disease worldwide, with millions of human cases of leptospirosis occurring annually and case fatality rates as high as 20% to 25% in some regions.1 Human infection results from exposure of mucous membranes or broken skin to infected urine from carrier mammals, either directly or through contamination of soil or water.2 Typical reservoir hosts of common Leptospira serovars are dogs (Canicola); rats (Icterohemorrhagiae and Australis); raccoons, squirrels, and skunks (Grippotyphosa); pigs (Pomona); and horses (Bratislava).2,3 Human infection occurs in both industrialized and developing countries, but the incidence is higher in the tropics than in temperate regions because of longer survival of leptospires in the environment in warm and humid conditions.2,4 The reported incidence of leptospirosis in people reflects as much the availability of laboratory diagnostic methods and the index of clinical suspicion as the true incidence of disease.4 Leptospirosis has recently been classified as a reemerging infectious disease, particularly in tropical and subtropical regions.5 However, this may also reflect a greater awareness of the disease and more rigorous attempts to diagnose it.6
Important risk factors in zoonotic transmission of Leptospira organisms are the climate and biotic interactions between wildlife, companion animals, and humans. Human infections may be acquired through occupational, recreational, or vocational exposure. Indeed, occupation is a substantial risk factor as most infections in farmers, veterinarians, abattoir workers, and meat inspectors occur by direct contact with infected animals.4 The risk of occupational transmission to veterinarians has been well documented in farm animal practitioners but less so in companion animal veterinarians.7 Transmission to pet owners has also been reported.4,7
Leptospirosis in dogs is fairly common in western Switzerland, in part because of its climate and wildlife populations.8,a In 1 study8 on healthy dogs in the surroundings of Bern, 16 of 30 (53%) dogs were seropositive for antibodies against Leptospira serovars with titers > 1:800 in 7 (23%) dogs. This high prevalence is similar to that observed in southern Europe; in a study9 of 240 dogs in Italy, 29% were seropositive for antibodies against Leptospira serovars. In addition, the University of Bern Vetsuisse Faculty Small Animal Clinic attracts a large number of dogs with leptospirosis because it is one of the few European centers offering intermittent hemodialysis for the treatment of acute kidney injury in companion animals. The hospital staff at this institution therefore has a high risk of exposure to infected urine or blood. Owners of dogs with leptospirosis have a similar high risk of infection (of which they are often unaware) because infection may occur either by direct inoculation from their pet or by exposure to leptospires in the same environment from which their dog acquired the infection. Despite these risks, serologic surveys designed to evaluate the rate of seropositivity in these human populations have not been described. The purposes of the study reported here were to assess patterns of seroreactivity to Leptospira serovars in veterinary professional staff and dog owners exposed to dogs with acute leptospirosis and to contrast these seroreactivity patterns in people with those observed in dogs.
Complement fixation test
Microscopic agglutination test
Francey T. Clinical features and epidemiology of presumptive canine leptospirosis in western Switzerland (2003–2005) (abstr). J Vet Intern Med 2006;20:1530–1531.
Copies of the questionnaires are available from the corresponding author upon request.
Department of Clinical Microbiology, Institute for Infectious Disease (IFIK), University of Bern, Bern, Switzerland.
Institute for Clinical Microbiology and Immunology (IKMI), St Gallen, Switzerland.
Institute of Veterinary Bacteriology, National Center for Zoo-noses, Bacterial Animal Diseases and Antimicrobial Resistance, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
NCSS 2007, NCSS LLC, Kaysville, Utah.
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