Infectious keratoconjunctivitis at the wildlife-livestock interface from mountain systems: dynamics, functional roles and host-mycoplasma interactions /
- Autores: Xavier Fernández Aguilar
- Directores de la Tesis: Jorge R. López Olvera (dir. tes.), Oscar Cabezón Ponsoda (dir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2017
- Idioma: español
- Tribunal Calificador de la Tesis: Pier Giuseppe Meneguz (presid.), Laila Darwich Soliva (secret.), Joaquín Vicente Baños (voc.)
- Programa de doctorado: Programa Oficial de Doctorado en Medicina y Sanidad Animales
- Materias:
- Enlaces
- Resumen
Infectious keratoconjunctivitis (IKC) is an ocular disease that affects wild and domestic Caprinae species. Epidemiology of IKC may rely in complex multi-host systems at the wildlife-livestock interface of alpine areas, where contrasting hypotheses of reservoir hosts have been proposed based on limited data. The main objective of this thesis is to provide comprehensive epidemiological data in order to infer the functional roles of domestic and wild host populations from mountain systems.
In the Study I and Study II, the epidemiological situation of Mycoplasma conjunctivae in small domestic ruminants from mountain areas in two distant regions (Northern Spain and Pakistan), seasonally sympatric with wild host populations, was studied in order to assess the potential source risk they suppose for their sympatric wild counterparts. Mycoplasma conjunctivae was commonly detected in the Pyrenees and the Karakoram mountain range, and more rarely in the Cantabrian Mountains. The relatively high prevalence of mostly asymptomatic infections observed suggests that sheep (Ovis aries) is a good host for the endemic maintenance of M. conjunctivae with a low host-biological cost (i.e. clinical signs and body condition). Chlamydiaceae was also endemic in the eyes of sheep and goats (Capra hircus) from Pakistan and could be a predisposing factor for IKC that needs of further research (Study II).
The long-term dynamics of M. conjunctivae and its molecular epidemiology in the whole community of wild and domestic hosts from the Pyrenees and Cantabrian Mountains was assessed in the Study III. Results showed that independent M. conjunctivae sylvatic and domestic cycles occurred at the wildlife-livestock interface in the Pyrenees. Specific M. conjunctivae strain clusters were maintained in some Pyrenean chamois (Rupicapra p. pyrenaica) populations without the substantial contribution of other hosts. Furthermore, host population characteristics and M. conjunctivae strains resulted in different epidemiological scenarios in chamois, ranging from the fading out and the epidemic persistence of the mycoplasma in lower density populations and the endemic persistence in a higher density population. Nevertheless, incidental cross-species transmission of M. conjunctivae occurred between chamois and mouflon and between chamois and sheep. Despite most of the IKC cases in free-ranging chamois were not associated with concurrent sheep strains, domestic sheep may have been historically important for the introduction of M. conjunctivae in wild hosts. This is suggested in the Studies II and III by the consistent epidemiological scenario observed in sympatric sheep and chamois from the Cantabrian Mountains and the Pyrenees.
In the Study IV, the transition from epizootic IKC to high prevalence of asymptomatic M. conjunctivae infections is described in a captive Iberian ibex (Capra pyrenaica) population, in which the host-mycoplasma interaction evolved to decreased clinical signs, lower mycoplasma loads and probably longer persistence in the eyes (Study IV). This study also provides evidences of the potential role of wild hosts in M. conjunctivae maintenance, associated to different and dynamic epidemiological scenarios.
Finally, in the Study V, the detection of M. conjunctivae in other locations apart from the eyes was explored in different host species in relation to transmission routes and within-host persistence. Transmission of Mycoplasma conjunctivae has been reasserted to be possible through direct contact from ocular and nose secretions and indirectly by eye-frequenting flies (Musca sp.). Mycoplasma conjunctivae was also detected in the ear canals, which may have important epidemiological implications.
Overall, the results obtained highlight the capacity of M. conjunctivae to establish diverse interactions with its hosts and persist in the population, also with different transmission patterns. Host populations and species can act either as maintenance hosts or as spill-over hosts depending on host- and M. conjunctivae-related factors. Population characteristics may also shape host-mycoplasma interaction through connectivity among individuals, M. conjunctivae transmission, and ultimately may determine its persistence and host functionalities in the system.
