According to what observed by Swiss authors (Bouvier et al., 1958; Burgisser, 1973, 1975, 1983) and to some review papers (Moutou & Artois, 1987; Gauthier et al., 1991b), the most important infective diseases of Alpine ibex, which in most cases are transmitted from domestic ungulates to wildlife, are the following(Balbo et al., 1978; Montagut et al., 1981; Rossi et al., 1985; Lanfranchi & Rossi, 1985; Lanfranchi & Rossi, 1987; Rossi et al., 1988; Bourgogne, 1990; Rossi, 1990; Cordier, 1991; Gauthier, 1991c; Lanfranchi et al., 1991; Peracino & Bassano, 1991; Peracino et al., 1993): i. diseases caused by bacteria: infective cheratoconjunctivitis, pasteurella, caseous lymphadenitis, brucellosis, clamidiosis, Q fever, Johne’s disease, tuberculosis, enterotoxemia, salmonellosis, yersiniosis, pseudotuberculosis; ii. Viral diseases: contageous ecthyma, rabbies, footh and mouth disease, respiratory and gastro-intestinal virus diseases; iii. Parasitic diseases: ecto-parasitic diseases (mange, tick and louse infestations, dermatomyiasis); endo-parasitic diseaes (protozoa: coccidiosis, red-water fever, sarcosporidiosis; helmints: taeniasis, respiratory and gastro-intestinal strongylosis, flatworm infesatations).

The pathogenic agents are often present in the environment and domestic species can act as vectors. There is, however, an equilibrium between pathogenic agent and its host, so that the appearance of some predisposing factors (such as environmental modifications, meteorological conditions or changes in population density) only, can determine the clinic manifestation of the disease (Moutou & Artois, 1987; Artois et al., 1990).
A good example of these etiological and pathological mechanisms is represented by infective keratoconjunctivitis . The aetiology of this disease has been for long time debated and different bacteria have been considered responsible (Micoplasma conjunctivae, Chlamydia sp. e Branhamella ovis: Klingler et al., 1969; Nicolet & Freundt, 1975; Gauthier, 1991c; Mayer et al., 1996; Mayer, et al. 1997; Giacometti et al., 1997a; Giacometti et al., 1998). Only recently it has been finally demonstrated that it is due to the infection by ovine strains of Micoplasma conjunctivae (Giacometti et al., 1998), identifiable with the analysis of ribosomal RNA (Giacometti et al., 1999), and often spread in domestic sheep herds where the infection often evolves with no symptoms (Giacometti et al., 1998). The evolution of this disease in Alpine ibex is often benign and after the etiological and clinic healing, follows a long period of resistance characterised by an evident antibdy reaction (Degiorgis, 1998). In the transmission of this important pathology, the sympatry amond domestic and wild ungulates plays a fundamental role, as well as possibly the presence of dipters vectors of Mycoplasma sp. (Degiorgis, 1998).