Chlamydia pecorum Associated With an Outbreak of Infectious Keratoconjunctivitis in Semi-domesticated Reindeer in Sweden.

Javier Sánchez Romano,Morten Tryland,Åsa Hagström,Mikael Leijon,Tomas Jinnerot,Ulrika K Rockström

doi:10.3389/fvets.2019.00014

Javier Sánchez Romano, Morten Tryland + Show 4 more

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https://doi.org/10.3389/fvets.2019.00014

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Abstract

Infectious keratoconjunctivitis (IKC), the most common ocular disease in ruminants worldwide, has affected semi-domesticated Eurasian reindeer (Rangifer tarandus tarandus) for over 100 years, both as individual cases and in outbreaks affecting tens to hundreds of animals. Recurrent IKC outbreaks have been affecting a semi-domesticated reindeer herd in Östra Kikkejaure (Norrbotten county, Sweden) from 2014. The latest episode of these recurrent outbreaks, in winter 2016/2017, was investigated in this study. Clinical findings were in line with previous reports of IKC in semi-domesticated reindeer and the clinical signs displayed by the affected animals (n = 30) included increased lacrimation, follicular conjunctivitis, purulent secretions around the affected eyes and corneal edema. Laboratory analyses of the samples revealed the presence of Chlamydiaceae in most samples obtained from the clinically affected animals (98.3%, n = 60), but also a high seroprevalence of cervid herpesvirus 2 (CvHV2) antibodies (56.6%, n = 53). Moraxella bovoculi was isolated from nine IKC-affected animals during the outbreak (45.0%, n = 20). All affected animals were treated with long-acting antibiotics and recovered from the disease, testing negative for the presence of Chlamydiaceae DNA by PCR 16 days and 3 months after the initial treatment. For the first time, Chlamydia pecorum was identified in semi-domesticated reindeer, and the involvement of Chlamydiaceae in a clinical outbreak of IKC is reported. The CvHV2 seroprevalence (56.6%) and the data obtained from a previous outbreak in 2014 also suggest the involvement of the reindeer alphaherpesvirus in the recurrent outbreaks.

Highlights

Infectious keratoconjunctivitis (IKC) is regarded as one of the most common transmissible ocular diseases in ruminants worldwide, with numerous examples of domestic and wild susceptible species and a great variety of causative and presumably causative agents reported [1,2,3,4,5,6,7,8,9,10]
The clinical signs reported during this outbreak of IKC in reindeer were indistinguishable from previous reports of IKC in reindeer, which underlines the difficulties of diagnosing the causative agent of an outbreak solely based on clinical observations
This is the first time C. pecorum has been reported in semidomesticated reindeer

Summary

Introduction

Infectious keratoconjunctivitis (IKC) is regarded as one of the most common transmissible ocular diseases in ruminants worldwide, with numerous examples of domestic and wild susceptible species and a great variety of causative and presumably causative agents reported [1,2,3,4,5,6,7,8,9,10]. Bacteria of the family Chlamydiaceae are widely distributed and highly prevalent in humans and animals, being the cause of ocular, reproductive, respiratory, and urinary tract diseases, and some of them representing zoonotic threats [17,18,19]. The classification of this family was revised based on ribosomal RNA and divided it in two different genera, Chlamydia and Chlamydophila [20]. Chlamydial keratoconjunctivitis in ruminants is, in the early stages, characterized by bilateral epiphora, chemosis, and conjunctival hyperemia, progressing to prominent conjunctival follicle formation and corneal neovascularization [32]

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