The Harry M. Zweig Memorial Fund for Equine Research  Virulence
Factors of Serovar Pomona and Vaccine Development  Dr. Yung-Fu
Chang  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 this bacterium causes
uveitis (periodic ophthalmia), chronic and severe ocular pain
leading to blindness, abortion, fever and icterus (jaundice). 
Leptospira induced uveitis is the most significant ocular
disease of horses.  Currently, there is no vaccine against
equine leptospirosis. Most veterinarians use commercially
available vaccines for cattle. These vaccines contain heat- or
formalin-killed leptospires and produce only incomplete, short-
term immunity.  Further, the need for an equine vaccine against
leptospirosis is exemplified by r