[Detection of leptospira by culture of vitreous humor and detection of antibodies against leptospira in vitreous humor and serum of 225 horses with equine recurrent uveitis].

The research article focused on examining the connection between a bacterial infection, leptospira, and equine recurrent uveitis (ERU) in horses. The study detected the presence of leptospira and antibodies to leptospira in the serum and vitreous humor of 225 horses.

Objective and Methodology

• The main aim was to explore the relationship between leptospira infection and ERU, a common and serious eye condition in horses, whose causes are still under discussion.
• The researchers performed two main tests: culturing of the vitreous humor from the patient horses to check for leptospira, and a microscopic agglutination test (MAT) to identify specific leptospiral antibodies in serum and vitreous humor.
• Samples were gathered from 225 horses of various ages, breeds, and genders, suffering from ERU. For most of these horses, vitreous humor was collected during surgery, while for a smaller group it was collected after eyeball removal. Preoperative serum samples were also collected.
• As a control group, 20 horses, which were put down due to diseases other than ERU, were used.

Research Findings

• A positive serum antibody response was observed in 57.5% of the ERU horses (127/221). The most often detected antibodies were against L. interrogans serovar Grippotyphosa, followed by two other serovars.
• However, the vitreous humor showed leptospiral antibodies in only 35.1% (79/225) of the horses. Again, the majority of detected antibodies were against L. interrogans serovar Grippotyphosa, followed by two other serovars.
• Leptospira was successfully cultured from 16% of the vitreous humor samples collected from ERU patients, indicating an active infection.
• Among the control group, 10/20 horses had a positive serum antibody titer against leptospira, and 2/20 had detectable antibodies in the vitreous humor. However, no leptospira were found in culture.
• The high number (84%) of negative cultures from vitreous humor samples of ERU patients was taken as significant for diagnosing and treating ERU.

Significance and Conclusions

• The findings demonstrate that while there is a high rate of leptospira infection among ERU patients as shown by the presence of antibodies in the serum, less of these patients show evidence of antibodies in the vitreous humor.
• The low rate of actual bacterial cultures from vitreous humor suggests that while Leptospira infection is common in ERU horses, it may not be directly causing or present in all cases of ERU.
• That said, the findings reinforce the need for further investigation into the role of leptospira infection in the aetiopathogenesis of ERU.