|POLLE, FLORENCE - Louisiana State University|
|STOREY, ERIC - Louisiana State University|
|EADES, SUSAN - Louisiana State University|
|ZUERNER, RICHARD - Retired ARS Employee|
|CARTER, RENEE - Louisiana State University|
Submitted to: Equine Veterinary Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/14/2014
Publication Date: 12/1/2014
Citation: Polle, F., Storey, E., Eades, S., Alt, D.P., Hornsby, R.L., Zuerner, R., Carter, R. 2014. Role of intraocular Leptospira infections in the pathogenesis of equine recurrent uveitis in the Southern United States. Journal of Equine Veterinary Science. 34(11-12):1300-1306.
Interpretive Summary: Leptospira spp are pathogens that can cause clinical illness in livestock and humans. A disease syndrome in horses, recurrent uveitis, has been linked to infection of horses with Leptospira spp. In this study, we used serology, PCR, and bacterial culture methods to evaluate the association between recurrent uveitis in horses and Leptospira infection. We found that 71% of horses exhibiting recurrent uveitis symptoms have some indication of Leptopsira exposure, compared to 4.7% of control horses which did not demonstrate symptoms. Our study indicates an association between Leptospira infection and recurrent uveitis in horses. This work will be of value to livestock owners and veterinarians in guiding treatment options for horses demonstrating clinical symptoms of recurrent uveitis. Because Leptospira can cause human infections, this work may also have public health implications in that cases of recurrent uveitis may indicate a potential risk for clinical disease in humans.
Technical Abstract: To investigate the role of intraocular leptospiral infections in horses with Equine Recurrent Uveitis (ERU) in the southern United States, blood and ocular fluid samples were collected from horses with a history and ocular findings consistent with ERU. Samples were also obtained from control horses with normal ophthalmic examinations. Leptospira serology was performed using microscopic agglutination test (MAT). Aqueous and vitreous humor samples were aseptically obtained and submitted for aerobic culture and Leptospira culture, PCR and MAT from twenty-one control horses (40 eyes) and 31 ERU horses (46 eyes). Serology results were available for 48/52 horses: 16/21 control and 23/27 affected horses were positive for at least one serovar; Bratislava was the most common serovar for both groups. Bacillus sp. and Micrococcus sp. were cultured from one control eye; Streptococcus sp. (n=1) and Leptospira (n=6) from eyes with ERU. Leptospira isolated belonged to serogroup Pomona (n=4) and Grippotyphosa (n=2). PCR results were positive in 14/31 (45%) horses diagnosed with ERU; no control horses were positive by PCR (p=0.0001). MAT was positive for 17/24 of ERU horses (71%) and 1/21 (4.7%) of normal horses (p<0.0001). Horses with ERU had a high prevalence of Leptospira infection based on PCR and MAT results from intraocular fluids compared to controls. The diagnosis of these intraocular infections was not aided by serology and required specific, invasive sampling of ocular fluid. Leptospira infection should be considered as a cause of ERU in the southern United States and treatment adapted accordingly.