Leptospirosis: preventing a complex and elusive disease

LEPTOSPIROSIS remains a challenging disease to the veterinary profession, and particularly to the small animal practitioner. Although leptospirosis was discovered in people nearly 100 years ago, is known to have a worldwide distribution, is of zoonotic significance and has been documented in dozens of mammalian species (Adler and de la Pena Moctezuma 2010), it is perhaps surprising how much we have still to learn about many aspects of this disease. Harboured in multiple wildlife reservoir hosts, thus ensuring the organism cannot be eradicated, the pathogenic spirochete has extensive genetic diversity. This heterogeneity contributes to the varied severity and presentation of clinical signs, and complicates taxonomic classification of the infective organism. Just as a full knowledge of its pathophysiology evades our mental grasp, the bacteria seek to evade a host's immune response by downregulating several outer membrane proteins (Haake and Matsunaga 2010). The host's humoral response, in the form of agglutinating antibodies, has been used for many years to help identify and group antigenically related strains. Culture of urine or blood remains the gold standard to identify infection, but growing the organism is difficult. The serovars Icterohaemorrhagiae and Canicola have been most associated with canine infections in North America and Europe for many years, and vaccines with these serovars have been the mainstay of protection for over 40 years. Maintained in murine and …