Leptospirosis has been an important cause of zoonosis for many years, but serovars have not remained constant. Leptospira icterohaemorrhagiae and L. canicola used to be the most common serovars seen in the United States, but today the most common are L. bratislava, L. grippotyphosa, and L. pomona. Vaccines on the market may not immunize against these serovars, although new vaccines do immunize against the latter two. The organisms are shed in the urine of the host, and the bacteria can survive in a warm, moist environment. The number of cases in a specific year correlates to the amount of rainfall the previous spring. Diagnosis of the disease is usually based on a combination of clinical signs, serology, and clinicopathologic and imaging data. Although kidneys are the most commonly affected organ, the liver is also often damaged. Vasculitis and disseminated intravascular coagulopathy may be more common than previously thought. Treatment includes fluid therapy and other supportive care for the organs involved and antibiotics. Caution should be exercised by people who come in contact with the patient, as the organism is zoonotic.

COMMENTARY: Leptospirosis is considered a reemerging infectious disease in both rural and urban areas of the United States. The reported incidence in people is 100 to 200 cases per year, although it is most likely underdiagnosed. Information about the serovars involved can help control this zoonotic disease.

Canine leptospirosis. Goldstein RE. ACVIM PROC, 2004, pp 573-575.