Chlamydia pecorum associated with an outbreak of infectious keratoconjunctivitis in semi-domesticated reindeer in Sweden

Abstract

Infectious keratoconjunctivitis (IKC), the most common ocular disease in ruminants worldwide, has affected semi-domesticated Eurasian reindeer (<i>Rangifer tarandus tarandus</i>) 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 (<i>n</i> = 30) included increased lacrimation, follicular conjunctivitis, purulent secretions around the affected eyes and corneal edema. Laboratory analyses of the samples revealed the presence of <i>Chlamydiaceae</i> in most samples obtained from the clinically affected animals (98.3%, <i>n</i> = 60), but also a high seroprevalence of cervid herpesvirus 2 (CvHV2) antibodies (56.6%, <i>n</i> = 53). <i>Moraxella bovoculi</i> was isolated from nine IKC-affected animals during the outbreak (45.0%, <i>n</i> = 20). All affected animals were treated with long-acting antibiotics and recovered from the disease, testing negative for the presence of <i>Chlamydiaceae</i> DNA by PCR 16 days and 3 months after the initial treatment. For the first time, <i>Chlamydia pecorum</i> was identified in semi-domesticated reindeer, and the involvement of <i>Chlamydiaceae</i> 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.