It is leptospirosis abortion season once again in Kentucky. The University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) has confirmed 11 leptospirosis abortions so far in the 2012-2013 reproductive season. Last year, 24 were confirmed for the entire season.
Leptospirosis carriers - Pastures and forage
Leptospirosis is the second most commonly identified infectious cause of abortion in mares following Equine herpes virus-1(EHV1).
Leptospirosis is caused by a group of highly invasive spiral bacteria (spirochetes) that are capable of infecting people and animals, including horses. Transmission occurs either through direct contact with an infected animal or through indirect contact with soil or water contaminated with urine from infected animals. Infection of horses with Leptospira causes uveitis (periodic ophthalmia), corneal opacity, abortion, and fever and icterus.
Currently, there is no vaccine against equine leptospirosis. Many veterinarians use commercially available vaccines for cattle. These vaccines contain heat or formalin-killed leptospires and produce only incomplete, short-term immunity. The need for an equine vaccine against leptospirosis is highlighted by recent outbreaks of the disease in New York and other States including Missouri, Pennsylvania and Kentucky.
Leptospirosis is the second most commonly identified infectious cause of abortion in mares following Equine herpes virus-1(EHV1). According to sources at the Gluck Equine Center at the University of Kentucky, abortions are expected to continue for about three more months during 2013.
Leptospirosis is a transmissible disease of animals and humans caused by infection with the spirochete Leptospira. Previous studies in Kentucky suggest that leptospirosis was the leading cause of abortion in domestic animals, mostly horses (1989) and the third the most common bacterial cause of abortion diagnosed from 1986 through 1991.
Clinical leptospirosis in horses, cattle, and companion animals is often associated with recent exposure, directly or indirectly, to surface water contaminated by rat urine. Affected horses typically live in an environment that combines a pasture and a stable shared with a number of small mammals. In winter most at-risk horses are fed roughage, which is almost inevitably contaminated by mouse, raccoon, and often rat urine.
A definitive leptospirosis diagnosis is very difficult to obtain because Leptospira takes up to 13 weeks to culture, and it is often hampered by other bacterial contaminants.
The gold standard for diagnosing leptospirosis is the microscopic agglutination test (MAT), in which patient sera are reacted with live antigen suspensions of major leptospiral serovars. However, MAT works only with serum and cannot be used with urine or fresh tissues, and it is often difficult to differentiate an active infection from previous exposures.
Other diagnostic methods include serological assays such as an enzyme-linked immunosorbent assay (ELISA), fluorescence antibody (the UKVDL’s method for confirmation on fetal tissues), and immunohistochemistry.
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