IntroductionInfectious keratoconjunctivitis (IKC) is recognised world-wide as a common condition affecting the eyes of domesticsheep and goats (36, 61). In the European Alps, IKC alsooccurs frequently in free-ranging Alpine chamois(Rupicapra r. rupicapra) and Alpine ibex (Capra i. ibex) (27).In addition, IKC has been described in other wild Caprinaespecies, such as Pyrenean chamois (Rupicapra p. pyrenaica)

in the Pyrenees (10, 52), European mouflon (Ovis o.musimon) in France (12, 55, 59), and Himalayan thar(Hemitragus jemlahicus) in New Zealand (13). Infectiouskeratoconjunctivitis is a specific ocular diseasecharacterised by inflammation of the conjunctiva andcornea. In the most advanced stages, the cornea is opaqueor even perforated (45). The principal single cause of IKCin chamois, ibex, and other Caprinae species (includingdomestic sheep and goats) is Mycoplasma conjunctivae (3).

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Infectious keratoconjunctivitis of ibex, chamoisand other Caprinae

M. Giacometti (1), M. Janovsky (2), L. Belloy (3) & J. Frey (3)

(1) Wildvet Projects, CH-7605 Stampa, Switzerland(2) Institute of Animal Pathology, University of Berne, Länggasstrasse 122, CH-3012 Berne, SwitzerlandPresent address: Landesveterinärdirektion, Wilhelm Greilstrasse 25, A-6020 Innsbruck, Austria(3) Institute for Veterinary Bacteriology, University of Berne, Länggasstrasse 122, CH-3012 Berne, Switzerland

SummaryInfectious keratoconjunctivitis (IKC) caused by Mycoplasma conjunctivae is ahighly contagious ocular infection which is common in domestic sheep and goats.In the European Alps, IKC is often observed in Alpine chamois (Rupicapra r.rupicapra) and in Alpine ibex (Capra i. ibex), but the disease has also beendescribed in other wild Caprinae in the Pyrenees and in New Zealand. Theinfection is characterised by inflammation of the conjunctiva and cornea, and inthe most advanced stages, the cornea is opaque or even perforated. In IKCoutbreaks in chamois and ibex, spontaneous recovery is the most prevalentoutcome of the disease. However, mortality can occasionally reach 30%. Recentstudies in eastern Switzerland indicated that M. conjunctivae infection is not self-maintained in chamois. In contrast, the disease is endemic and self-maintained inthe domestic sheep population. Spillover of the agent from sheep living inproximity during summer may be the origin of point-source epidemics in wildCaprinae. Flies are likely to play a central role in interspecific transmission ofM. conjunctivae on alpine meadows. When outbreaks of IKC occur in wildlife, aspecial effort should be made to avoid unnecessary human disturbance inaffected areas. However, animals presenting irreversible ocular lesions should beshot by professional gamekeepers to prevent suffering. Prevention of IKC in wildCaprinae should focus on preventing the spillover of M. conjunctivae fromlivestock. However, studies are required to evaluate the distribution ofM. conjunctivae infection in domestic sheep in several countries and to assessthe risk of IKC spillover from domestic animals to wildlife. In addition,immunological studies should be performed to develop tools which could lead tothe control of M. conjunctivae infection in domestic sheep.

KeywordsAlpine chamois – Alpine ibex – Caprinae – Clinical disease – Epidemiology – Infectiouskeratoconjunctivitis – Mycoplasma conjunctivae – Sheep.

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The first reported outbreak of IKC in wild Caprinae (Eineinfektiöse Kerato-Conjunktivitis bei Gemsen) dates from 1916and refers to chamois in the Austrian Alps (58). Since then,numerous outbreaks have been described in other alpinecountries, including Switzerland (1, 9, 15, 23, 38, 53), Italy(6, 11, 32, 41), France (29, 33, 42) and Slovenia (62).However, the origin of outbreaks of IKC remains unclear inmost cases, and description of disease progression isusually incomplete due to the difficulty of recognising mildIKC symptoms in remote segments of the habitat.Furthermore, habitats of wild Caprinae populations areoften politically subdivided (24), and collaboration amongadministrative units at the population level, essential forcomplete IKC records, is not yet common.

Importance for animal healthInfectious keratoconjunctivitis caused by M. conjunctivae isan inflammatory condition of the conjunctiva and cornea indomestic and wild Caprinae. In the early stages, the diseasepresents as a unilateral or bilateral conjunctivitis withhyperaemia of the vessels. Untreated cases may progress tomucopurulent conjunctivitis and corneal ulcerationresulting in opaque corneas and transient blindness. Indomestic Caprinae (sheep and goats), IKC is a nuisance tofarmers since animals require treatment and some nursingto reduce the period of blindness (17).

The impact of IKC on sheep health is comparatively low; ininfected sheep herds, symptoms are moderate or absent inadults, and in lambs, M. conjunctivae is generally onlymildly pathogenic. Outbreaks associated with severesymptoms are usually observed when the agent isintroduced into naive herds by infected animals purchasedfrom other flocks (2, 46).

While IKC usually provokes mild symptoms in domesticsheep and goats, the consequences in wildlife can be fatal.Blind chamois and ibex face particularly treacherouscircumstances in steep rocky areas and affected animalsmay fall from cliffs. In wild Caprinae, the disease may alsoprogress to ruptured corneas (Fig. 1) and lead to death dueto starvation if perforation is bilateral. In particularsituations, mortality can reach 30% and have a markedimpact on demography.

AetiologyThe term IKC is used to describe a clinical condition whichis not always ascribable to the same infectious agent (36).Aetiology of IKC in chamois and other wild Caprinaespecies has been a matter of debate for a long time (30).Several agents, including Branhamella ovis, Chlamydia

psittaci, Corynebacterium pyogenes, M. conjunctivae, Rickettsia(Colesiota) conjunctivae and Staphylococcus aureus have beensuspected as aetiological agents of IKC (21). However, indomestic sheep, pathogenicity has been demonstrated foronly two of the micro-organisms which have been isolatedfrom the eyes, namely: C. psittaci and M. conjunctivae (36,37, 63). Pathogenicity of M. conjunctivae has also beendemonstrated in the domestic goat (61), Alpine ibex (25)and European mouflon (59), and in addition, this agent hasbeen implicated as the aetiological agent of IKC in Alpinechamois (15, 32, 50). Mycoplasma conjunctivae is nowgenerally agreed to be the principal single cause of IKC indomestic and wild Caprinae (3). Phylogenetically, M. conjunctivae belongs to the Mycoplasma neurolyticumcluster of the hominis group, and this agent is closely relatedto M. bovoculi and M. ovipneumoniae (51).

The first isolation of M. conjunctivae from sheep eyes wasperformed by Surman in Australia in 1968. The agent wasdescribed and named by Barile et al. in 1972 (5).Mycoplasma conjunctivae has been isolated from domesticsheep and goats in North America, Europe, South Africa,Saudi Arabia and Australia (39, 63). In most countries,seroprevalence in domestic Caprinae is unknown.Therefore, further epidemiological studies are required toelucidate the extent of the infection.

Klingler et al. first isolated M. conjunctivae from chamois in1969 (38). The strains were identified six years later byNicolet and Freundt (50). More recently, M. conjunctivaehas been detected in two other wild Caprinae species,namely: Alpine ibex (44) and European mouflon (59).However, M. conjunctivae is also likely to be present in otherspecies of Caprinae, such as Himalayan thar and Pyrenean

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Fig. 1Right eye of a chamois (Rupicapra r. rupicapra) affected byinfectious keratoconjunctivitisThe cornea has perforated and presents a cicatrix. Blindness isirreversible in this case

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chamois. Presumably, M. conjunctivae is specific forCaprinae in general (i.e. goats, sheep and their relatives).

Laboratory diagnosisIn wild Caprinae, the occurrence of several animalsshowing bilateral keratoconjunctivitis in a distinct regionwithin a short period is likely to be associated with an M. conjunctivae infection. However, diagnosis ofmycoplasmal IKC requires detection of M. conjunctivae or ofspecific M. conjunctivae antibodies in affected animals.

The classical method for the diagnosis of M. conjunctivaeinfections is isolation of the organism by culture andsubsequent identification by immunological methods (18,48). For culture, eye swabs are dipped into Transwab®

transport medium and processed within 24 h of collection.Culture is performed on standard mycoplasma brothmedium enriched with 20% horse serum, 2.5% yeastextract and 1% glucose (4).

Culture of M. conjunctivae is cumbersome and requiresspecialised technical experience. Therefore, a specificpolymerase chain reaction (PCR) assay was recentlydeveloped for the rapid direct detection of this pathogen inclinical material (26). For detection of M. conjunctivae byPCR, conjunctival swabs are dipped in tubes withouttransport medium and stored at –18°C until analysis.Nested PCR is based on unique sequences of the rrs genes(16S ribosomal ribonucleic acid [rRNA]) of M. conjunctivae.Sensitivity of nested PCR is usually higher than thatobtained by cultivating the mycoplasma. Furthermore,identification of M. conjunctivae by nested PCR does notrequire special care in the transportation of the samples.This method plays a central role in the diagnosis of IKC inCaprinae.

An indirect enzyme-linked immunosorbent assay (ELISA)method based on the Tween 20 extracted fraction of M. conjunctivae strain HRC/581T has recently beendeveloped to detect M. conjunctivae antibodies in sera ofdomestic sheep (7). For the analysis of the sheep sera,serum is diluted 1/10, applied to the plates and analysedusing a commercially-available monoclonal antibodydirected against ruminant immunoglobulin G (IgG)conjugate to horseradish peroxidase, according to theinstructions provided by the manufacturer. The opticaldensities are measured with a photometer at a wavelengthof 405 nm. The value of each sample is expressed as apercentage of a positive reference standard, taking anegative reference serum as zero value. The cut-off level(37%) was set 3 standard deviations higher than the meanvalue for negative controls according to the test validation(7). At present, studies are being performed to develop andevaluate an ELISA to be used in Alpine chamois (28).

Clinical manifestationsand pathologyThe first visible signs of IKC are hyperaemic conjunctivaand congestion of conjunctival vessels associated withserous or mucous effusions (Fig. 2). In the initial stages ofinfection, the conjunctiva is infiltrated with mononuclearcells (2, 36, 45). Conjunctivitis can persist for some weekswithout any sign of keratitis, but the disease may progressto more severe forms. Mild keratitis is characterised byeither oedema with accompanying infiltration ofneutrophils or by perilimbic neovascularisation withmostly mononuclear inflammatory infiltration. Perilimbicneovascularisation can occur without preceding cornealoedema in the vertex area when keratitis is mild (45).Vascularisation occurs in response to a variety of cytokinesreleased by damaged corneal epithelium, stromalkeratocytes, or immigrant leukocytes, rather than as aresponse to the oedema (19). Superficial oedema is variablein the more advanced cases, but is always severe, eitherwith marked neovascularisation or necrosis. Cornealulceration may occur in severe cases, and mixed cellularinfiltration is present when neovascularisation extends tothe ulcerated area. According to Wilcock, ulceratedepithelia lead to infiltration with neutrophils, andneutrophils may be present in response to secondarybacterial infection (64). In the most severe cases, corneamay perforate. Ruptured corneas show anterior synechiaand melanin deposits forming staphyloma (45). The stagesare progressive, but healing may commence at any time,unless the cornea is ruptured.

Fig. 2Infectious keratoconjunctivitis in domestic sheep: lambshowing reddened, swollen eyelids and sero-mucous oculareffusion

Infectious keratoconjunctivitis caused by M. conjunctivae isa non-generalised, specific ocular disease. The otherorgans, including lungs, show no alterations suggestive ofchanges induced by M. conjunctivae. The absence of

pathological changes in the brain of blind ibex and chamoispresenting circling movements suggests that in wildCaprinae affected by IKC, changes in behaviour are notnecessarily a consequence of cerebral lesions. Such changesmay simply be due to disorientation and stress in totallyblind animals (15, 45).

Biology of infectionIn IKC, the period of incubation after experimentalinfection with M. conjunctivae is short (two to four days) (8,25, 37, 63). In individual animals, clinical signs last twoweeks to two months. However, after the disappearance ofsymptoms, animals can act as healthy carriers of M.conjunctivae. The eyes of sheep without clinical signs of IKCwere nevertheless found to be infected with the agent ofIKC (35, 37, 40, 46). However, persistence ofM. conjunctivae infection in individual animals does notexceed three to six months (35). Similar to the situation insheep, bacteriological results in Alpine ibex suggest atemporary persistence of M. conjunctivae only (25).

In Caprinae, immune response to M. conjunctivae infectionsappears to be strong. In experimental infections, specificantibodies, as detected by immunoblot analysis, appearedtwo to four weeks post infection (16). Immunoblot analysisallowed identification of the principal specificimmunogenic proteins of M. conjunctivae in naturally- andexperimentally-infected chamois, ibex and domestic sheep(Fig. 3). Major immunogenic proteins using sera hadmolecular masses of 175, 83, 68, 60, 50, 42, 36 and 33kDa. Antibodies to the 175, 73, 68, 60 and 33 kDa antigensappeared to be specific to M. conjunctivae. Naturally-infected animals demonstrated much stronger immunereactions than those infected experimentally (16).However, little is known about the protective effect ofacquired immunity. Although preliminary results indomestic sheep indicate that clinical signs may be weakerin the course of a second M. conjunctivae infection, theimmunity acquired is insufficient to resist naturalinfections.

In outbreaks of IKC in chamois and ibex, spontaneousrecovery is the most prevalent course of the disease (20).Mortality is usually low (<5%), and in most reports, lessthan fifty dead chamois were recorded during the course ofan IKC epidemic. However, in particular situationsmortality can reach 30%. Examples associated with a highmortality in chamois are outbreaks of IKC in the GranParadiso (Italy) and Vanoise (France) National Parks from1981 to 1983 (33, 41), in the Aosta Valley (Italy) in 1998(32), and in the Simmental-Gruyère-Region (Switzerland)from 1997 to 1999 (15). In Simmental-Gruyère, a total of420 chamois died of the consequences of IKC (Fig. 4). This

is the highest number of deaths reported during an IKCoutbreak since 1919, when the first epidemic in chamoiswas described in the Alps by Stroh (58). The reason fordifferences in mortality is still open to question; thosesuggested are differences in virulence of distinct M. conjunctivae strains, particular predisposition of hosts(e.g. genotype, health condition, overcrowding), secondaryinfections or environmental predisposing factors (e.g. ultraviolet-irradiation) (47). Recovery of demographicparameters in the post-epidemic period is rapid or occurswithin a time lag of five to six years (42), depending on themortality rate observed.

In wild Caprinae, mortality has been associated with IKC,especially in females and juveniles (10, 15, 21, 28, 53). Thenumber of affected adult males recorded is usually low,possibly reflecting a lower percentage of this sex/age-classwithin populations of chamois. This would not besurprising, since in some regions the number of old male

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Fig. 3Immunoblot of sera (s) and conjunctival washes (w) to wholecell antigens of Mycoplasma conjunctivaeSamples from three chamois with severe keratoconjunctivitis (the firstsix lanes) and one healthy chamois (far right). The molecular sizemarkers are given in kDa on the left (M)

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chamois hunted is disproportionately high compared toother sex/age-classes (22). Furthermore, sexual segregationof adult males and solitary living during most of the year could lower the probability of infection with M. conjunctivae (56).

Epidemiology of infectionTransmission of Mycoplasma conjunctivaeMycoplasmal IKC is highly contagious within herds (2);the agent, M. conjunctivae, is excreted in ocular effusions.Given that mycoplasmal organisms do not survive for along time in the environment, transmission must occurthrough direct contact or after a short delay. According torecent publications, mycoplasmas can be spread via aerosol(43, 57) and by eye-frequenting insects (14, 31). However,intraspecific transmission of M. conjunctivae does notrequire vectors and occurs predominantly or exclusively bycontact (40).

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On alpine meadows in Switzerland, IKC occurs at the sametime in the same regions in several host species (23, 50),and short-distance encounters between free-rangingindividuals of different Caprinae species, domestic andwild, are not uncommon events in the Alps (M.-P. Ryser-Degiorgis, P. Ingold, H. Tenhu, A.M. Tébar, A. Ryser and M. Giacometti, unpublished data). Therefore, interspecifictransmission of M. conjunctivae between domestic and wildCaprinae species is likely to occur. However, interspecificbody contacts are rare, and the probability of interspecifictransmission of infectious agents by physical contactappears to be rather low. For IKC, encounters cannevertheless be considered as a predisposing factor for theinterspecific transmission of M. conjunctivae; aerosolinfection or transmission by eye-frequenting insects (Fig. 5)are possible, and the probability of interspecifictransmission increases as distance between animalsdecreases. Excessive lachrymation is an attractive source ofproteins, salt and water for insects (49, 65), and the feedinghabits of flies include constant changing of hosts grazing

Fig. 4Distribution of 420 chamois (Rupicapra r. rupicapra) which died of the consequences of infectious keratoconjunctivitis from 1997 to1999 in the Simmental-Gruyères region of the north-western Swiss AlpsDifferent colours are used for different time periods (all three months, except for the first and the last time periods which lasted two months each).Brown triangles represent mountain peaks, black squares represent villages, and rivers are presented in blue

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close to each other. Four genera of Muscidae wereidentified as potential vectors of M. conjunctivae, namely:Hydrotaea, Musca, Morellia and Polietes (14). Flies are likelyto play a role as accessorial vectors, but their role might beof primary importance in interspecific transmission of M.conjunctivae on alpine meadows.

In chamois, epidemics of IKC progress at an average speedof 15 km/year (15), which is three to four times faster thanthe progression reported for sarcoptic mange in chamois inthe eastern Italian Alps (54). This may be associated withdifferences in host density, social organisation and habitatmorphology, but the highly contagious character of IKCmay play the most important role in faster progression. Insome outbreaks of IKC, intraspecific transmission ofM. conjunctivae occurs throughout the year (15). However,losses due to IKC in chamois are more frequent during thesummer and autumn (28). This coincides with thepresence of domestic sheep grazing on summer pastures.

Maintenance of Mycoplasma conjunctivaein host populationsPersistence of infections in animal populations isprincipally determined by the potential of the pathogen tomaintain its life cycle in the host and by characteristics ofthe host population such as number of individuals,percentage of susceptible animals within the populationand interaction between animals (60). A recent study in theeastern Swiss Alps (28) indicated that M. conjunctivaeinfection is not self-maintained in alpine chamois. Thismay be due to the limited contact between chamois fromdifferent herds and to the fact that persistence of infectionin individual animals does not exceed three to six months,as shown in sheep (35).

In contrast to the situation in wild Caprinae, M. conjunctivae infection is endemic and self-maintained in

the domestic sheep population in Switzerland (35). Atleast one positive animal was detected in 89% of the herds,and in positive herds, 57% of the individual animals testedpositive. Risk factors for maintenance of M. conjunctivaeinfections in domestic sheep have not yet been studied. InSwitzerland, herd size did not appear to play an importantrole, but regional differences were not particularly relevant.The mixing of sheep for grazing, shows and markets, theintroduction of new animals to a flock, as well as thepresence of (susceptible) lambs during most of the yearappear to enable maintenance of M. conjunctivae infectionwithin the national sheep population. Importantly, thedisease can be spread to other flocks by infected sheepwhich are cl inical ly healthy. In contrast , theinterrelationship with wild Caprinae does not appear to bea condition of maintaining infection, as shown by studiesin Switzerland. In sheep, IKC occurs in winter, at whichtime these animals are housed and no encounters withchamois and ibex occur. In addition, M. conjunctivaeinfections in sheep occur in countries where free-rangingsusceptible wild Caprinae species are absent, such as theNetherlands (39), the United Kingdom (34) and SouthAfrica (63).

Treatment and preventionIn free-ranging Caprinae, identification of affected animalsin remote segments of the habitat is difficult. Spillover ofM. conjunctivae from domestic Caprinae may have occurredseveral weeks before the first affected animal is observed ina particular area, and the M. conjunctivae infection is thenlikely to have already spread within the whole herd. Inaddition, spontaneous recovery is the most prevalentcourse of the disease. Therefore, culling all animals affectedwith IKC, regardless of the severity of IKC signs, is aninappropriate method of disease control.

A special effort should be made to minimise unnecessaryhuman disturbance in affected areas (e.g. cross-country-walks and uncontrolled hunting), to avoid putting animalsto flight (which could lead to falls and injury or death),and to prevent long-distance movements of infectedanimals. Migrating animals could transmit M. conjunctivaeto neighbouring, non-infected herds and widen thediseased area. Individuals which either present irreversibleocular lesions (corneal perforation) or are in poor generalcondition and/or injured should be shot by professionalgamekeepers to prevent suffering. Treatment of affectedfree-ranging chamois or ibex should not be attempted.

Prevention of IKC in wild Caprinae should therefore focuson hindering the spillover of M. conjunctivae fromlivestock. Thus, use of salt licks should be restricted to aminimum to reduce the frequency of encounters between

Fig. 5Hydrotaea irritans on the right eye of a chamois affected withinfectious keratoconjunctivitis

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individuals of different Caprinae species. Domestic sheepshowing ocular effusion should be treated before beingmoved to alpine meadows during the summer. Topicaltreatments in domestic sheep should use broad spectrumantibiotics such as oxytetracycline or chlortetracycline, ineither ointment or powder form. Several treatments areoften necessary in severe cases and relapses commonlyoccur. Systemic (intramuscular) treatments may be appliedalternatively or additionally. Penicillin or streptomycin areineffective (36). Unfortunately, no vaccine exists againstinfections with M. conjunctivae in sheep.

PerspectivesInfection with M. conjunctivae is an exotic emerging diseaseof Caprinae. Infectious keratoconjunctivitis is probably notself-maintained in wild Caprinae populations, and spilloverof the agent from domestic sheep living in proximity duringthe summer may be the origin of point-source epidemics inwildlife. However, little is known about the occurrence ofIKC in sheep sharing pastures with wild Caprinae species.Therefore, studies are required to evaluate the distributionof M. conjunctivae infection in domestic sheep in severalcountries and to assess the risk of IKC spillover fromdomestic animals to wildlife. For this purpose, newmolecular and serological methods have recently beendeveloped for the rapid and specific detection of M. conjunctivae infections (7, 26). In addition, furtherstudies are needed to improve understanding ofmechanisms of interspecific transmission of the pathogenand to evaluate infection maintenance in both domestic and

wild Caprinae populations. In wild Caprinae, mortalityfollowing IKC outbreaks can reach 30%, and blindchamois and ibex face particularly treacherouscircumstances in steep rocky areas. The authors thereforesuggest further epidemiological and immunological studiesbe undertaken to develop tools which could lead to thecontrol of M. conjunctivae infections in domestic sheep.This includes molecular studies on pathogenesis anddevelopment of effective and safe vaccines forimmunoprophylaxis in sheep.

AcknowledgementsThe authors are grateful to P. Ratti and J. Nicolet whoinitiated and supported the study on infectiouskeratoconjunctivitis in Switzerland. Special thanks go tomany wildlife services, state gamekeepers, hunters, sheepowners and veterinarians for collecting data and samples inthe field, to D. Mayer and M.-P. Ryser-Degiorgis for helpfulcollaboration, to M. Krawinkler and Y. Schlatter for expertassistance with isolation, identification and cultivation ofmycoplasmas, as well as to W. Bommeli for the supply ofELISA plates. The study was supported by the Fund forResearch on Infectious Keratoconjunctivitis, Chur, by theSwiss Federal Office for Environment, Forests andLandscape, Berne, and by the Research Fund of theInstitute for Veterinary Bacteriology, Berne. This work ispart of the COST Action 826 on Ruminant Mycoplasmoses.

La kérato-conjonctivite infectieuse du bouquetin, du chamois etd’autres Caprinae

M. Giacometti, M. Janovsky, L. Belloy & J. Frey

RésuméLa kérato-conjonctivite infectieuse due à Mycoplasma conjunctivae est uneinfection oculaire très contagieuse, fréquente chez les ovins et caprinsdomestiques. Dans les Alpes européennes, la kérato-conjonctivite infectieuse estsouvent observée chez le chamois des Alpes (Rupicapra r. rupicapra) et chez lebouquetin des Alpes (Capra i. ibex), mais la maladie a également été décrite chezd’autres Caprinae sauvages dans les Pyrénées et en Nouvelle-Zélande.L’infection se caractérise par une inflammation de la conjonctive et de la cornée ;aux stades les plus avancés, il se produit une opacité, voire une perforation de lacornée. Chez les chamois et les bouquetins atteints de kérato-conjonctiviteinfectieuse, une guérison spontanée est l’issue la plus courante de la maladie.Cependant, la mortalité peut occasionnellement atteindre 30 %. Des étudesrécentes effectuées dans l’est de la Suisse montrent que l’infection due à

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M. conjunctivae n’est pas auto-entretenue chez les chamois. En revanche, lamaladie est endémique et auto-entretenue chez les ovins domestiques. Lecontact avec l’agent excrété par des ovins vivant à proximité pendant l’estivepeut être à l’origine d’épidémies ponctuelles chez les Caprinae sauvages. Lesmouches jouent probablement un rôle majeur dans la transmissioninterspécifique de M. conjunctivae dans les prairies alpines. Lorsque la kérato-conjonctivite infectieuse se déclare chez les animaux sauvages, il faut veiller toutparticulièrement à limiter les dérangements anthropogènes superflus dans leszones atteintes. Toutefois, les animaux présentant des lésions oculairesirréversibles doivent être abattus par les garde-chasse pour leur éviter desouffrir. La prévention de la kérato-conjonctivite infectieuse chez les Caprinaesauvages consiste essentiellement à empêcher la propagation deM. conjunctivae par les animaux domestiques. Cependant, des études doiventêtre faites pour analyser la répartition de l’infection due à M. conjunctivae chezles ovins domestiques dans plusieurs pays et pour évaluer le risque detransmission de la kérato-conjonctivite infectieuse des animaux domestiques à lafaune sauvage. De plus, des études immunologiques doivent être effectuées pourdévelopper des outils permettant de lutter contre l’infection due àM. conjunctivae chez les ovins domestiques.

Mots-clésBouquetin des Alpes – Caprinae – Chamois des Alpes – Épidémiologie – Kérato-conjonctivite infectieuse – Maladie clinique – Mycoplasma conjunctivae – Ovins.

Queratoconjuntivitis infecciosa del íbice, la gamuza y otrosCaprinae

M. Giacometti, M. Janovsky, L. Belloy & J. Frey

ResumenLa queratoconjuntivitis infecciosa causada por Mycoplasma conjunctivae es unainfección ocular extremadamente contagiosa que afecta con frecuencia a ovejasy cabras domésticas. En los Alpes europeos, la enfermedad se observa a menudoen la gamuza alpina (Rupicapra r. rupicapra) y el íbice alpino (Capra i. ibex),aunque también está descrita en otros Caprinae salvajes de los Pirineos y NuevaZelanda. Esta infección se caracteriza por la inflamación de la conjuntiva y de lacórnea, que en las fases más avanzadas se vuelve opaca o incluso se perfora. Enla gamuza y el íbice, el desenlace más frecuente de los brotes infecciosos es larecuperación espontánea. Sin embargo, la mortalidad puede alcanzar a vecestasas de hasta un 30%. Estudios recientes efectuados en el Este de Suizapusieron de manifiesto que la infección por M. conjunctivae no se automantieneen la gamuza. En las poblaciones de ovejas domésticas, en cambio, es endémicay automantenida. La propagación del agente a partir de ovejas trasladadas apastos de altura en verano podría ser la fuente de brotes de tipo localizado entreCaprinae salvajes. Las moscas son seguramente el principal vehículo detransmisión interespecífica de M. conjunctivae en las praderas alpinas. Cuandose declaren brotes de queratoconjuntivitis infecciosa entre la fauna salvaje, hayque hacer lo posible por evitar toda intrusión humana innecesaria en las zonasafectadas. No obstante, conviene que los guardas forestales sacrifiquen a losejemplares con lesiones oculares irreversibles a fin de evitarles sufrimientos.

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Para prevenir la aparición de la enfermedad en Caprinae salvajes es preciso antetodo evitar que M. conjunctivae se propague a partir de animales domésticos.Pero para ello se requieren estudios que determinen la distribución de lainfección en ovejas domésticas de diversos países y evalúen el riesgo depropagación de la fauna doméstica a la salvaje. Convendría además llevar a caboestudios inmunológicos que sirvan para elaborar técnicas aplicables a la luchacontra la infección en la oveja doméstica.

Palabras claveCaprinae – Enfermedad clínica – Epidemiología – Gamuzas alpinas – Íbices alpinos –Mycoplasma conjunctivae – Ovejas – Queratoconjuntivitis infecciosa.

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