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  Discussion on New study says Lepto not a cause?
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Member:
sbower

Posted on Tuesday, Nov 4, 2008 - 5:14 pm:

Dr O, I wonder if you have seen this study and could comment?

"Role of bacteria in the pathogenesis of recurrent uveitis in horses from the southeastern United States," was published in volume 69 of the American Journal of Veterinary Research, 2008
Moderator:
DrO

Posted on Wednesday, Nov 5, 2008 - 10:19 am:

Hello Shelly,
For those interested let me put the articles summary here:

American Journal of Veterinary Research
October 2008, Vol. 69, No. 10,
Pages 1329-1335

Role of bacteria in the pathogenesis of recurrent uveitis in horses from the southeastern United States

Brian C. Gilger, DVM, MS; Jacklyn H. Salmon, BS; Na Y. Yi, DVM, PhD; Curtis A. Barden, BS; Heather L. Chandler, PhD; Jennifer A. Wendt, BS; Carmen M. H. Colitz, DVM, PhD

Objective—To determine the role of intraocular bacteria in the pathogenesis of equine recurrent uveitis (ERU) in horses from the southeastern United States by evaluating affected eyes of horses with ERU for bacterial DNA and intraocular production of antibodies against Leptospira spp.

Sample Population—Aqueous humor, vitreous humor, and serum samples of 24 clinically normal horses, 52 horses with ERU, and 17 horses with ocular inflammation not associated with ERU (ie, non-ERU inflammation).

Procedures—Ribosomal RNA quantitative PCR (real-time PCR) assay was used to detect bacterial DNA in aqueous humor and vitreous humor from clinically normal horses (n = 12) and horses with chronic (> 3-month) ERU (28). Aqueous humor and serum were also evaluated for anti-Leptospira antibody titers from clinically normal horses (n = 12), horses with non-ERU inflammation (17), and horses with confirmed chronic ERU (24).

Results—Bacterial DNA was not detected in aqueous humor or vitreous humor of horses with ERU or clinically normal horses. No significant difference was found in titers of anti-Leptospira antibodies in serum or aqueous humor among these 3 groups. Only 2 horses, 1 horse with ERU and 1 horse with non-ERU inflammation, had definitive intraocular production of antibodies against Leptospira organisms.

Conclusions and Clinical Relevance—In horses from the southeastern United States, Leptospira organisms may have helped initiate ERU in some, but the continued presence of the organisms did not play a direct role in the pathogenesis of this recurrent disease.

In this research project Dr Gilger did not find evidence of increased leptospirosis exposure in the population as a whole compared with those with RU. There are several possible explanations for this two of which come to mind are:
1) Lepto is not associated with RU.
2) Lepto induced RU represents a subpopulation of horses that have become sensitized by their past infection.

I agree with Dr Gilger that lepto and its relation to RU remains conjectural and his findings do not strongly support a relation. It should be noted that other studies have found support for the idea however.
DrO
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