Untersuchung gesunder Pferdeaugen auf eine intraokulare Leptospireninfektion

Gesell-May, Stefan; Brem, Siegfried; Wollanke, Bettina und Gerhards, Hartmut (2021): Untersuchung gesunder Pferdeaugen auf eine intraokulare Leptospireninfektion. In: Pferdeheilkunde, Bd. 37, Nr. 3: S. 215-224

Abstract

Equine recurrent uveitis presents as an acute manifestation of a chronic recurrent serohemorrhagic inflammation of the uvea. This disease can be treated with great success using the pars plana vitrectomy technique. Introduction of this surgical technique as well as routine diagnostic aqueocentesis performed on equine eyes has provided substantial intraocular material for diagnostic evaluation and scientific research. In equine eyes with recurrent uveitis it was possible to concomitantly isolate leptospires as well as leptospira specific antibodies regardless of the stage of disease. In comparison, leptospires can only be detected in the blood of experimentally infected horses for up to nine days. Clinical signs of recurrent uveitis often first appear months, or even years, after spontaneous or experimental systemic infection has occurred. Is it possible for leptospires to actively invade the eye during the stage of bacteremia and persist without initiating an immediate local immune response? Isolation of leptospires or their DNA from anamnestic and ophthalmoscopic inapparent eyes revealing no antibody titers possibly explains the long period of incubation in this disease. The objective of this study was to provide evidence of leptospiral presence in ophthalmologic healthy equine eyes. Intraocular material from 168 ophthalmologic healthy eyes from 100 horses were subjected to MAT, indirect ELISA and culture testing for the presence of intraocular infection with leptospires. PCR was implemented to screen 120 specimens from 60 horses determined to be free from ocular disease for the presence of leptospiral DNA. Intraocular samples from 14 eyes obtained from horses diagnosed with ERU served as the control group. Additionally, the serum from 71 horses without ERU, and the serum from 25 horses with ERU were tested for the presence of leptospiral antibodies using the MAT. From the 168 specimens taken from the healthy eyes, only one eye (0.6 %) revealed a positive antibody titer in the MAT and ELISA, whereas, none of the cultures were positive (0.0 %). The PCR was positive for leptospiral DNA in 6/120 eyes (5.0 %) with concomitantly negative antibody test results. In the control group 14/14 cases in the MAT (100 %) and 13/14 cases (93.0 %) in the ELISA revealed antibodies. Culture and PCR were positive simultaneously in 8 samples (57.0 %). Comparison of the healthy eyes and eyes with ERU in the chi-square-test revealed a significant difference (p < 0,001) independent of the method used (MAT, ELISA, culture, PCR). No significant difference (p = 0,066) could be detected between the 53/71 (75.0 %) horses without signs of ERU and the 23/25 (92.0 %) horses with signs of ERU in the serological MAT. In conclusion 1) a subclinical leptospiral infection of the vitreous body, if at all possible, is restricted to isolated cases. The appearance of DNA in ophthalmologic healthy eyes with simultaneously negative antibody results could possibly be interpreted as an intraocular leptospiral infection that has evaded recognition from the host's immune system. Nevertheless, it was not possible to culture living leptospires. 2) Further evidence of the relationship between ERU and intraocular leptospiral infection was presented. 3) Because antibodies were only detected in the aqueous humor of 1/168 ophthalmologically asymptomatic eyes included in this study, diagnostic aqueocentesis should only be carried out on such eyes in exceptional situations.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Tiermedizin > Zentrum für Klinische Tiermedizin
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• ISSN: 0177-7726
• Sprache: Deutsch