Dynamics of an Infectious Keratoconjunctivitis Outbreak by Mycoplasma conjunctivae on Pyrenean Chamois Rupicapra p. pyrenaica

Abstract

Between 2006 and 2008, an outbreak of Infectious Keratoconjunctivitis (IKC) affected Pyrenean chamois Rupicapra p. pyrenaica, an endemic subspecies of mountain ungulate that lives in the Pyrenees. The study focused on 14 mountain massifs (180,000 ha) where the species’ population is stable. Cases of IKC were detected in ten of the massifs and, in five of them, mortality was substantial. The outbreak spread quickly from the first location detected, with two peaks in mortality that affected one (2007) and three (2008) massifs. In the latter, the peak was seasonal (spring to autumn) and, in the former, the outbreak persisted through winter. To identify the outbreak’s aetiology, we examined 105 Pyrenean chamois clinically affected with IKC. TaqMan rt-PCR identified Mycoplasma conjunctivae in 93 (88.5%) of the chamois. Another rt-PCR detected Chlamydophila spp. in 14 of chamois, and 12 of those had mixed infections with mycoplasmas. In the period 2000–2007, the chamois population increased slightly (λ 1.026) but decreased significantly during the IKC outbreak (λ 0.8, 2007–2008; λ 0.85, 2008–2009) before increasing significantly after the outbreak (λ 1.1, 2009–2010). Sex-biased mortality shifted the adult sex ratio toward males (from 0.6 to 0.7 males per female) and reduced productivity slightly. Hunting was practically banned in the massifs where chamois experienced significant mortality and allowed again after the outbreak ended. Long-term monitoring of wild populations provides a basis for understanding the impacts of disease outbreaks and improves management decisions, particularly when species are subject to extractive exploitation.

Postepizootic Persistence of Asymptomatic Mycoplasma conjunctivae Infection in Iberian Ibex

“…However, there were no age class differences in M. conjunctivae in the ibexes in 2014, suggesting that this potential age factor may be dynamic and dependent on the established interaction between the hosts and the circulating mycoplasma strains. In contrast with previous reports of IKC epizootics in sheep and chamois (27,(40)(41)(42), more severe clinical signs and higher mycoplasma DNA loads were exhibited by kids than adults in this study. It suggests that in this case, ocular tissue damage was apparently directly caused by M. conjunctivae and was probably less influenced by the adverse effects of exacerbated immune responses (2,20,43).…”

“…Clinical signs during the IKC outbreak in 2013 were as severe as those reported in other IKC outbreaks in wild Caprinae (27,33) and in naive domestic sheep flocks (25,34). According to the progression of clinical signs and the molecular and serological results, the IKC outbreak probably started before July 2013, and clinical resolution (no severe IKC stage II or III) was observed by November 2013.…”

“…Both epidemiological situations (i.e., IKC outbreak and endemic asymptomatic infections) have been described in other domestic (16,25) and wild free-ranging (12,20,26,27) hosts. The results of the present study show how both epidemiological situations can occur consecutively in a host population, depending on M. conjunctivae circulation, its maintenance in the population, and the progression of the host-pathogen interactions.…”

Infectious keratoconjunctivitis in wild Caprinae: merging field observations and molecular analyses sheds light on factors shaping outbreak dynamics

“…It may be that secondary microbial agents compete with the mycoplasmas in late disease stages [5, 8, 22] or that part of the observed IKC-like signs are due to another etiology [4]. In addition, false negative results may be due to a reduced sensitivity of the test in highly contaminated samples.…”

“…Most recently, the existence of a strong association between M. conjunctivae infection and IKC signs has also been documented in epidemiological surveys [4, 22] and M. conjunctivae is now recognized as the major etiological agent of IKC in Caprinae species.…”