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.

Figure 1. Study area.

Mountain massifs in the study area within the Spanish Pyrenees. 1. Ori; 2. Ezkaurre; 3. Larra – Peña Forca; 4. Bixaurín; 5. Anayet; 6. Biñamala; 7. Monte Perdido; 8. Liena; 9. Punta Suelsa; 10. Posets; 11. Maladeta; 12. Cotiella; 13. Sierra Ferrera; 14. Turbón. Grey indicates the area directly managed by the regional administration in Aragon.

Figure 2. Spatial distribution over Pyrenean massifs of IKC-outbreak locations for years: A) 2006, B) 2007 and C) 2008.

Figure 3. Pyrenean chamois found dead in the Aragonese and Navarrese Pyrenees.

Figure 4. Trend of Pyrenean chamois in the Aragonese and Navarrese Pyrenees.

Figure 5. Adult female and kid affected with IKC.

Figure 6. IKC-affected female whit many flies around the head.

Figure 7. Stages lesion of IKC in Pyrenean chamois during 2006–2008 outbreak.

Pictures show animals with different levels of disease severity. A) Purulent ocular lacrimation and mild corneal opacity (stage II). B) Corneal opacity (stage III). C) Late stage of IKC, with purulent exudation, evident conjunctivitis and corneal perforation (stage IV). D) Animal without lacrimation that had chronic corneal lesions showing the face without hair.

Figure 8. General view of the stage IV lesion of IKC in Pyrenean chamois.

Note the ruptured Descemet’s membrane and synechia with the incarcerated iris and severe keratitis.