Serum and vitreous humor antibody titers in and isolation of Leptospira interrogans from horses with recurrent uveitis.

The research article focuses on detecting the antibody levels against Leptospira interrogans in horses experiencing recurrent uveitis (inflammatory eye disease), and determining the prevalence of this bacteria in their vitreous humor (substance in the eye). Findings suggest that a continuous eye infection with Leptospira interrogans is widespread amongst horses suffering from recurrent uveitis, and the typical method of determining infection presence by comparing antibody levels may not be effectively reliable.

Research Objective and Methodology

• The primary goal of this study was to discover the prevalence of Leptospira interrogans in the vitreous humor of horses struggling with recurrent uveitis along with measuring antibody titers.
• The researchers used a cross-sectional study design that included 242 horses (270 eyes) with recurrent uveitis that underwent vitrectomy and 39 control horses (54 eyes) with no history or clinical symptoms of uveitis.
• The serum and vitreous humor of these horses were tested for antibodies against 13 serovars of L interrogans and their vitreous humor was sent for leptospiral culture.

Key Findings

• Leptospira interrogans was identified in vitreous humor of 120 out of 229 horses (52%) or 126 out of 252 (50%) eyes) with recurrent uveitis.
• The bacteria could not be found in the vitreous humor from 36 eyes of 21 control horses.
• 38% of the horses from which the bacteria were isolated had been dealing with recurrent uveitis for a year or more.
• The average antibody titers against L interrogans in the vitreous humor and serum of horses with recurrent uveitis were 1:1,332 and 1:186, respectively.
• However, only 91 of the 120 horses isolated with the bacteria showcased a 4-fold or greater difference between the serum and vitreous humor antibody titers.

Implications

• The results from this research imply that chronic ocular infection with Leptospira interrogans is frequent in horses suffering from recurrent uveitis.
• A 4-fold increase in vitreous humor v/s serum antibody titers might not be a sensitive test for diagnosing L interrogans-induced recurrent uveitis, which suggests the need for improved diagnostic procedures.
• The paper hypothesizes that the immune component of recurrent uveitis can be directly stimulated and preserved by the ongoing infection of the eye with Leptospira interrogans.