Role of Intraocular Leptospira Infections in the Pathogenesis of Equine Recurrent Uveitis in the Southern United States
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© 2014 Elsevier Inc. Equine recurrent uveitis (ERU) has been linked to leptospirosis in Europe; however, regional differences exist in reports from the United States. The objective of this study was to investigate the role of intraocular leptospiral infections in horses with ERU in the Southern United States. Blood and ocular fluid samples were collected from horses with ERU and normal controls. Leptospira serology was performed using microscopic agglutination test (MAT). Aqueous and vitreous humor samples were obtained and submitted for aerobic and Leptospira culture, polymerase chain reaction (PCR), and MAT. Twenty-one control horses (40 eyes) and 31 ERU horses (46 eyes) were available. Serology was available for 48 of 52 horses: 16 of 21 control and 23 of 27 affected horses were positive for at least one serovar; bratislava was the most common serovar identified. Bacillus sp. and Micrococcus sp. were cultured from one control horse's eye; Streptococcus sp. (n = 1) and Leptospira (n = 6) were cultured from the eyes of six ERU horses. Leptospira isolates belonged to serogroup pomona (n = 4) and grippotyphosa (n = 2). Polymerase chain reaction results were positive in 14 of 31 (45%) horses with ERU; no control horses were positive by PCR (P = .0001). Microscopic agglutination test was positive for 17 of 24 ERU horses (71%) and one 21 (4.7%) normal horses (P < .0001). Horses with ERU had a high prevalence of Leptospira infection based on PCR and MAT results from intraocular fluids compared with control horses. The diagnosis of 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.
author list (cited authors)
Polle, F., Storey, E., Eades, S., Alt, D., Hornsby, R., Zuerner, R., & Carter, R.