Is the development of infectious keratoconjunctivitis in Alpine ibex and Alpine chamois influenced by topographic features?

摘要

Infectious keratoconjunctivitis (IKC) caused by Mycoplasma conjunctivae is a widespread ocular affection of free-ranging Caprinae in the Alpine arc. Along with host and pathogen characteristics, it has been hypothesized that environmental factors such as UV light are involved in the onset and course of the disease. This study aimed at evaluating the role of topographic features as predisposing or aggravating factors for IKC in Alpine chamois (Rupicapra rupicapra rupicapra) and Alpine ibex (Capra ibex ibex). Geospatial analysis was performed to assess the effect of aspect (northness) and elevation on the severity of the disease as well as on the mycoplasmal load in the eyes of affected animals, using data from 723 ibex and chamois (583 healthy animals, 105 IKC-affected animals, and 35 asymptomatic carriers of M. conjunctivae), all sampled in the Swiss Alps between 2008 and 2010. An influence of northness was not found, except that ibex with moderate and severe signs of IKC seem to prefer more north-oriented slopes than individuals without corneal lesions, possibly hinting at a sunlight sensitivity consequent to the disease. In contrast, results suggest that elevation influences the disease course in both ibex and chamois, which could be due to altitude-associated environmental conditions such as UV radiation, cold, and dryness. The results of this study support the hypothesis that environmental factors may play a role in the pathogenesis of IKC.