FileList Convert a pdf file! Koedoe 19: J-15 (J976) AN OUTBREAK OF DERMATOPHILOSIS IN SABLE HIPPOTRAGUS NIGER AND ROAN HIPPOTRAGUS EQ.UINUS IN THE KRUGER NATIONAL PARK " V. DE vas DiviJion ?fNature Conservation Pn'vate Bag X404 Skukuz.a JJ50 C. D . IMES H Lt. Col. , USAF, VC, Zoonotic Pathology Divi5ion Armed Forces Institute of Pathology Walhinglon D.C. , 20J06 Ab5t racl - A severe skin disease diagnosed as dennatophilosis took on alarming proportions in roan antelope Hippotragus equinus and sa ble antelope Hippotragw niger herds, which were kept in a 256 ha enclosure in the Kruger National Park, Republi c of South Africa. Only calves were effected. Nume- rous DmnatophilUl organisms were identified in skin biopsies taken from affected areas and examined histologically. Com- plete recovery fo llowed a single treatment of intramuscular injections of a co mbination of a long-acting penicillin and stre ptomycin and the topical application of a preparation which included copper sulphate and benzene hexachloride. Factors which probably contributed to the outbreak included prolonged wetness, flies , a high density of susceptible animals and playful butting behaviour of the calves. This is the first report of the occurrence of dennatophilosis as a disease entity in wildlife species in southern Africa. 6 The views expresSfd he rei71 are those oj the aUlhoTJ a7ld are not to be CQmtrued aJ official or as reflecting the lJiews oj the U. S . Air Foret or the Department of DeJenu . U Tnlljwwl')' aJsignmwt - Secti071 rif Pathology, Velen'nary Resea rch /mlilu le, Onder- stepoorl OJ 10, Republic oj South Africa. Introduction The distribution of the disease entity known as dermatophilosis (c utaneous streptothricosis, senkobo disease, mycotic dennatilis l among domestic animals such as caule, sheep and horses is world-wide (Plowright 1956; Austwick 1969; Searcy and Hulland 1968). The disease was initially reponed in South Africa during 1928 from sheep (Bekker 19281. Since then it has been found that the disease is widespread in South Africa among cattle and sheep (Steyn 1931; Schulz 1956), particularly along the eastern escarpment with its high summer rainfall and greater humidity (Rossiter 1969). This area lies adj"acent to South Afi·ica '5 greatest wildlife concentration and largest wild ife sanctuaries. Yet so far as we aware the disease has not hitheno been described in southern Afri can wildlife species. The position is very much the same elsewhere. Austwick ( 1969) commented on this phenomenon by pointing OUl that the actinomycete Dermatophilw congo/emu causes one of the commonest skin diseases of domestic animals and yet few cases have been reponed in wild animals. Vague reports from tropical Africa indicate that the girailc Giraffa came/opardalis, Thomson's gazelle Ga u lle thormorn· (MacKenzie and Simpson 1964 ) and a zebra Equus sp. (Green 1960) have been found to be mildly infected. In temperate regions the di sease has been reponed from the white-tailed deer Odocoilew virginia - nw (Dean, Gordon, Severinghaus, Kroll and Reilly 1961; Kistner, Sholts and Green 1970), a cottontail rabbit Sylvilagus jloridanw (Shotts and Ki stn er 1970 ), young chamois Ru.picapra rupicapra (Nicolet, Klinger and Fey 1967 ), polar bears rhaLarctos maritimw (Smith and Cordes 1972 ), owl monkeys Aotw trivirgatw (King, Fraser, Garcia, Wolf and Williamson 1971), a fox Vulpes vulpes (Austwick 1969 ) and sea lions Otaria bryonia (Frese and Weber 1971) . According to Stewart (1972 ) Kusel'tan reported infection in hares, hedgehogs and gerbils. The disease is zoonotic and was experimentally produced in man by Memery and Thiery (accord- ing to Stewart 1972). Natural infection occurred in four men who skinned and handled an infected deer carcass (Dean et al. 1961) and one of us (G.D.I.) had a focal, self limiting skin lesion on a finger from care- less handling of infc:ctious material. Rubel (1972 ) strongly implicated D. congolemu as the cause of pitted keratolysis, a skin condition affecting the fOOL soles of people in Zaire. History The roan antelope Hippotragw equ.inw is comparatively rare through- o ut its range in Africa. This is especially true for the Kruger National Park (K.N.P ') where there is a small population of 250 to 300 animals causing considerable concern for their chances of survival Uouben 1970). It was, therefore, decided to launch an intensive investigation into the bio-ecology of this rare species. To provide realistic study opportunities and simultaneously build up a population from which 2 groups could be released periodically to augment the natura l popula- ti o n, it was decided to erect an invio late enclosure of 256 ha in the most favo urable roan hab itat in the no rthern distric t o f the K.N .P. This encl os ure is hereafter referred to as the Camp. A nucleus herd of 10 ro an were released in the Camp without mishap in 1967 (Pienaar 1968 ; J o ub ert 1970). After promising res ults were achieved initiall y, 13 sab le antelope HippolragUJ niger, a lso a rare species in South Africa, were placed in th e sa me enclosure during Au gust 1969 and May 1970. The respective nucleus herds did exceedingly well initiall y. The roan antelope herd, however , suffered a severe setback in 1970 when 15 out of a to tal o f 27 animals died from anthrax (unpublished data, de Vos ). In spite of morta li ty of unkno wn aetio logy which th e yo ung calves of both species suffered sporad icall y, the numbers aga in increased to 48 for sable and 26 for roa n a ntelo pe at the beginning of March 1974 . Shortly th ereafter, however, two deaths among young sable antelope ca lves occurred but du e to interfere nce by scavenger birds no worth - while specimens for diagnosis were available. It was decided to th o ro ughl y examine rema ining anima ls in the Camp in an attempt to detemline the ca uses o f the unexplained deaths. MateriaLs and Method.s OperationaL The enclosure was entered and the roan and sable herds approached by means of a vehicle. Preliminary observations o f the animals o n hoof were made from th e ve hicle. A pair of 10 x 50 binoculars aided in the close'· exa mination o f individuals. Affected animals were subseq uentl y caug ht by th e drug immo bilization technique. A Pa lmer Cap-C hur gas- po~cred rifle was used to pro pel two ml capacity darts or projectill' synnges. To lessen the disturban ce factor the recumbent a nimals were saken by vehi cle to a properl y eq uipped po int of operations o n th e periphery of the Camp for closer examination, sampling and treaonent. Skin bio psies were taken fro m the worst affected areas of each indi- vidua l a nd preserved in Milio nig' s 10% buffered fo nnalin . In addition deep skin scrapings were collected in a 50% glycerine/a lco ho l solution . These specimens were processed and examined at a later date. The formalin-fixed tissues were prepared in a routine manner for light microsco py and stain ed with haematoxylin and eosin (HE), Giemsas and Gram's stains and the periodic acid Schiff (PAS ) reaction. Trea ted animals were marked by hairclipping, every individual having its own distinct and easily recog nizable identificatio n mark ·for fUlUre reference. After resuscitat io n th e animals were re leased in the immediate vicinity of the herd . During 15 to 20 April 1974 12 affected anima ls were ca ught a nd trea ted in this manner. In order to assess the co urse o f the disease without chemotherapeutic s interference, the leas t infected individual was omitted from the initial treatment , but was treated on the second visit to the Camp IO days afterwards. At the same time one of the previo usly treated indi viduals was caught and re -examined to determine the reaction to therapy. To det ennine whether infection occurred in the immediate surround - ings o f the Camp, the area was surveyed intensively b y means of binocula rs. The comparative abundance o f ticks inside and o utside the Camp was subjectively assessed by merely walking through the veld in the res pe<:tive areas. The amount of ticks attached to the person was taken as an indi - cation of abu ndance. Climate Data were obtained from the meteorological station at the Shingwedzi Rest Camp, situated 40 k.m to the so uth of the enclosure. Drugs The immobi lizing drugs and antidote used were : ElorphiM hydrochloride, M99 1 was used as the basic immobilizing age n t (Pienaar 1974 ). AzaperoM, R19 29' was used as a neuroleptic together with the M99 in the dan combinatio ns (Pienaar 1974 ). Nalorphine hydro- brol."lide, uthidrone' was used for its ' properties to antago nize th e narco ti c effects of mo rphine or a mo rphine derivative such as M99 (Pienaar 1974 ). For th era py o f th e skin co ndition , associated debility and stre ss, a se ri es of drugs and combinatio ns were used . The faculties for which th e drug was choosen, are mentio ned briefly in each case. Thioctic acid {Tioctan)4 was administered for liver invigoration, det o xifi- cation and meta bolic improvement. ProcaiM penicillin G and benetluzmiM penidlfin (Comprope n )5 was adminis tered in co mbination with dihydro - streptomycin (D iStrep)6 for its kno wn sy nergisti c action against D . congo- lemis (Roberts 1967; Smith and Cordes 1972). Selenium-Vitamin E (BO-SElf was administered fo r it 's beneficial effect on capture myo pahty as cle imed by Basso n and Hofmeyr ( 1973 ). Hydroxycobalamin ( Vit . B12b) (Neo Cytamen)1 with its prolonged blood level was used for its known beneficial effects in debilitated cases. BenUM I Rrd/ill and Som /) d . 1) (l1W(I! Pharlflauulica. ' BurrollghJ IVrllcomt and Company. fFuji:mWfl I'hamwuutical Co. ud. JGlaxo. AlItTlbuTy.l S.A. ( Pi} ) lid . 6A. S. Rllifr/(lJI\'I /Jr/ . IS.A. ()'llIl11midt /..Id. 'G/axo·A llrnbrtTyJ S. II . ( Ply) Ltd. 4 hexachloride, S. H.C. diluted in water to a concentration o f 0,0396 of th e gamma isomer was used as a wash for its know n paraciticidal effects and iu claimed beneficial effects o n th e co urse of d ermatophilosis (Plowright 1956 ). A dermatological preparation, applied topically was made up of: "Healing oi l"9, co ntaining 33,396 vegetable o il, 58,996 o leo resins and 0,596 gennicidal agent as the basis with copper JUlphaLe B.P. added to make 5% of th e fina l solution. Copper sulpha te was used for its useful anti- septic and potent fungicida l properties. It has been found beneficial in th e trea tment o f dermatophilosis in sheep (Moule 1948 ; Rossiter 19 56; Roberts 1957). Finally B. H .C. was added to tWo concentrations of about 0,025% of the gamma iso mer. 9C(){)p a and Nephews SA. ( /)1.1' ) Uri . Environmental Geographica ll y the Camp is situated in the northern region of the K. N. P. and occ upi es a 1,6 km area to the north and south of the 22<'47' latitude sou th a nd 3 1° 15' longitude east lines respectively. As is typica l for the rest of th e region the area is rather flat , with an a ltitude of about 390 m above sea level. The area co nsists mainly of a heavy '" '" ... '" • , . , " . • , • no • .. .. M JJASONOJ' .. A .. JJ .. SONOJ ...... "YOIogo lI71/H (1' -'.0' porlOd) .... .... m. 1 ... ' ....... Fi g . 1. H iSlOgram of the monthl y rainfall dislribulion for Shingwedzi Rest C,lJnp, Kruger National Park , during the period of and directly prt·, ced ing the outbrea k of dermalOphilosis . Yearly rainfall figures are includ ed li)r comparat ive purposes. 5 black basaltic soil type and the savannah vegetation type is dominated by th e tree and shrub [ann of the mopane (Colopho5permum mopane), hence the designation of this vegetation type as "rnopane scrub and tree sava nnah " (Pie naar 1963) . Other important tree and shrub species in- elude Combrelum imberbe, Sc/erocarya caffta, LQnchocQrpus capaJJo, Dalbergia melanoxylon and Grewia spp . The grass stratum is mainly co mprised o f Themeda lriandra, Panicum coloratum, Schmidtia pappophoroideJ, Cmchrw ciljaris, Heteropogon contortu.s, Digitaria spp. and Arislida spp. giving an overall " tall grass" appearance. Being at its peak stage of growth and as a result of exceptionally good rains (Fig. I), the green grass cover was es pecia l\ y lush during the lime of the disease outbreak. For the greater pan of th e Camp th e grass exceeded the sho ulder height of the yo unger , or affected animals. As depicted b y Fig. 1, exceptionally heavy rains were experienced during the season preceding the disease outbreak. Precipi- tation in th e form of heavy dew further intensified and prolonged exposure to moisture. The biting ny lipoptena paradoxa was panic ularly abundant and when wo rkin g with the calves these flies would swarm from them and settle o n the handlers. A subjective assessment of tick infestatio n indicated that there were greater numbers o n the vegetation inside than there was o u t- side the Cam p . Initial Examination Familiar to the occasional proximity of a vehicle within the Camp, it was poss ible to a pproach the animals with some caution to within 20 metres. At this distance and with th e aid o f 10 x 50 binoculars it was clear tha t some debilitating skin disease existed which affected the total calf crop, at the time consisting of seven sable and six roan ca lves. The ages ranged from about 2-4 months. They were variably infected , so me being obvio usl y in the early and others in more advanced stages of the di sease. Debilitation clearly paralleled the progressive stages of infection . The more severel y infected individuals showed a droopiness of the head and ea rs and frequently shoo k the ir head s as if the lesions were irritant. They often lagged b ehind the rest of the herd . Mild lachrymation was show n by the most seve rely infected individuals. Binocular examination o f animals outside the Camp for infection was also ca rried out, the immediate surrounding area being covered more intensively. No affected animals were detected. ImmobiliUZlion On 1974 .04.16 catching o peratio ns commenced and by 1974.04 . 19 12 of the 13 affected ca lves were ca ught for close examination, sampling of the sk in lesio ns and treatment. The animals were of uniform size and age a nd a d osage rate of 2 mg M99 and 40 mg Azaperone was used throughout. Animals went down in three to nine minutes after intra- muscalar d eposition of the drugs by Cap-Chur dart. This was, however, 6 only execUled with the utmost caution and patience. With too much activity around them, o r when hard pressed, the calves often resorted to hiding or laying up behaviour for long periods or even the rest of the day. Effective co unteraClion of the immobilizing drugs was achieved with the administration of 100 mg Lethidrone (60 mg intravenous and 40 mg intramuscu lar). The calves invariab ly got up within two minut es and joined the herd shortly afterwards. No fatalities occurred. Fig. 2. Fig. 3. Derrnatophilosis. sable ca lf. Patchy lesions around eyes and base orcaI'. Encrus ted hair in lesions over the withers. No te cap ture dart in ri ght hip. Dermatophilosis, sab le calf. Patchy lesions on cars and heavy enc r us- tatiun of mane down to with er s. 7 GrOjj Appearanu The sk.in condition was an ex udative dermatitis characterized by the [onnation o f crusts. Lesions ranged in size from small nodu le·li kc fom13tion s to large patches (Fig. 2) and in the more advanced stages who le regions of sk.in were covered with heavy encrustations of dry exuda te admixed with hair (Fig. g ). In the more severe cases a pumlent serous exudate exuded through cracks in the crust. In the early stages (he crusts were tenacious and on removal the skin beneath would appear moist and hyperaemic with minor haemorrhages in some cases. In the later stages the crusts co uld be removed more easily and in so me instances were o nl y held in place by penetrating hairs. The variety of lesions. or vario us stages of infectivity, made it possible to follow the seq uence of development of the les ions. In the earliest stage • 6 Fig . 4. Derma tophi los i s. Fig. 5. Dennatophilosis. • Low magnificati on showing layered exudate and acanthosis of epidermis. H Ex 30. Concent rat ion of organism s around hai r shaft in ('xudall" GicTO sa sta in x 500. Fig. 6. D . cOllgoltJ js. Branchin g and horizo ntal div isio ns. Giem sa Slain x I ZOO . Fig. 7. D . ( ollgoltJ iJ. Ho rizontal and transvcrse divisions fanning coccoi d spo res . Giemsa stain x IZOO . 8 on ly the rorehead and immediate VICIni£}, or the eyes were atlected. Lesio ns then appeared o n the dorsal aspects o r the head. neck. thorax and lumbar regions. From there it appeared to spread down the sides or the body and on the Icgs. The most severe case showed heavy coalesced encrusta ti o ns o r the dorsal aspects or the body, the lateral rib cage be- hind th e elbow, the sternal aspect and lower parts or th e legs. In this case the hair or the rest o r the body were unnaturally ereCl and on palpation revea led ro ughenin g or the skin surface due to numero us small (pea- size) isolated wart-li ke elevations. Nu mero us immature srages or Boophilw ticks were round o n th e animals, some even bei ng imbedded in the lesion encrustations. A rew Ambl)'omma and Rhipicephalw ticks were also round, mostly co nfined to the anal region. Hi jtopathologjcalfinding5 and Dtjinitive Diag1loju Pathological changes were primarily in the epid~rmis and co nsi sted or acamhos is and piling or cornified epithel ium and exudate on the epi - dermal surraces in a la yered rash io n (Fig. 4. 5, 6 and 7). This layered material contained neutro phils, which in some foci were conce ntra ted in a pustu la r-like fonnation . Within the exudate orga nisms were easily see n in H E sta ined sections. They were most plentiful around, but not invading hair sharts (Fig. 5) and in foci containing large numb ers of inflamatol)' cells. Organisms grew in a mycel ia -like ra shion (Fig. 6) and the growth fonnalion was divided both horizontally and longit udinall y form ing cocco id bodies up to 6 or 8 organisms across in the widest portions (Fig. 7). They stained well with Giemsa's and Gram's stains but PAS reaction was negative. Morphologically and histologicall y they were identified as D. congolmjiJ. The underlying dermis was infiltrated by neutrophils a nd small mononuclear cells and there was some fibroblastic proliferation. Therapy Ten days afler treatment (vide supra) a binocular re-examination re- vea led drastic and a clearcut improvement of previously affected indi - viduals. This was further borne o ut by catching and closely examining one of the ca lves which was judged to be severely infected prio r to treat- men t 12 days earli er. Scab fonnation had stop ped and the sk in was dl)' and pliable. The overall impression which was ga ined was that th e a nimal was on its wa y to full recovel)'. The disease in the untreated control calf had progressed fro m a limited inrect ion o n the forehead and around the eyes to a severe stage with crustformation o n the head. ears, back, sides, stern um and legs. Treatment was instituted at t.his time. As witnessed a month later al ani- mals showed a co mpletc clinical recovel)'. 9 DiJCWJion and ConciUJiom The gross skin lesio ns o f dennatophilosis are essentially th f: same in a ll animal species (Sm ith , J o nes and Hunt 1972) and those seen in the roa n and sable calves of this report co nfonn with th ose which have been described. The constant finding of Dt rmatophiltu organisms in skin lesions therefore warranted a diagnosis of dermatophilosis. The fungal- like appearance o f D . congolensiJ has led to names for the di sease such as mycolic dermatitis and cutaneo us streptothricosis. Cordo n ( 1964 ) d isproved its relations hip with fungi and regarded the above na mes as mislead ing impl ying rreaUfl ent should be antifungal in - stead of antiba cteria l. Roberts ( 1967 ) suggested " dennatoph ilus infec- ti o ns" be used for t he disease and Stewart ( 19 72) Slates the term "denna - top hilosis" is eq ua ll y exp li cab le. Jubb and Kennedy (1970) expressed the opinion that the older en trenched names, Le. cutaneous streptothricos is in ca ttle, mycotoc dennatitis in sheep and strawberry fOOtrOl in sheep be retained b ut recent reports of the disease have favo ured derma lophi losis. Alth ough th e epizootiologic pattern of dennatop hilosis is not com- pletely und ers too d , some fa ctors contributing to dis se mination of this di sease are kno wn . Organisms o f the genus Dtrma/.()philUJ undergo frag- mentation of the mycelia as a result o f multidimensio nal division and give rise to motile zoospores (Gordon and Edwards 1963; Cordon 1964 ; Ro berts 196 7). The reselVoir o f D. congoleruiJ in nat ure is, however, un - known. Attempts to isolate it from soil have been unsuccessful (Roberts 1963a ; Kaplan and J o hnsto n 1966 ). Roberts (1967) ma inlains tha t chro - ni ca ll y affected indi viduals are probab ly the o rga nism's chief mea ns of surv iva l with in a nock or herd during donna m periods. There is a lso evidence that the mi cro-orga nism co ncerned leads a sa prophytic life on th e skin and that it is no t until the equilibrium be[Wee n th e paras ite and host is disturbed by extra neous facto rs that it becomes a true pathogen (Cord on 1964 ). The mi cro-orga nis m which gave rise to th e present out- break must therefore have originated from a biological carr ier within th e Camp. There has been a rather co nsistem association between wet co nd itions o r hum idity a nd infec ti o n (Chod nik 1956; Plowright 1956; Scarnell 1961; Ie Ri che 1968 ). In add itio n Richard and Pier ( 1966) fo und that fli es, co ntaminated with D. congoiemil, infected rabbits more readily il' their skin was first wetted . Intense o r prolonged wetting of the skin appa rentl y results in emulsification and di sr uption of th e se baceo us film (Roberts 1963b ; Robe rts and Gra ham 1966) as well as maceration o f the stratum corneum , whi ch then becomes more penneable to irri tant substa nces (Suskind and Ishihara 1965) and probably more susceptible to di sturbance by mechanical agents (Roberts 1967). As depicted by Fi gure I exceptionally heavy rains were ex perienced during the seaso n preceding the disease OUlbreak. Wet co nd itions were furt her augmented by a high humidity with regular ni ghtly precipita - ti o ns in the form of heavy dew which nOl o nl y dampened individua ls 10 dose to the ground but also thoroughly moistened the t.all grass cove r. This provided almost contin uo us moist cond itions for the young ani- mals and must be considered partially respo nsible for the dramatic dif- ferential morbidity in which the ca lves were exclusively affected. How- ever, in Australia young animals appear more susceptible to infection than older sheep (Nesb it and Bannaryne 1955) and in Kansas, U.S.A. calves accounted for 33 of 39 cases reponed in calLIe (Kelly, Huston, Imes and Weide 1964 ), Roberts (l963b ) maintains that sheep lambs are bo rn with an incomplete sebaceous film that does not become fully protective for a pe riod varying from a few days to five or six weeks. This should not be a faclOr in the present outbreak as th e youngest roan and sable calves were at least two months o ld . The lesions of the infection are usually distributed in either of two quite different patterns - over the face , ears and body sugge st in g trans fer by insects , or on the li ps and legs suggesting transfer via the pasture (Roberts 196 7). In cattle in Africa the disease is closely associa ted with tick infestation, and the lesions develop main ly in those ventra l areas of the body most heavily infes ted with ticks (Plowright 1956; MacAdam 1964b ). Ticks of the genera Amblyomma, Boophilus, Haemaphysalis, Hya- lomma, Ixodes and Rhipicephalus have been incriminated as mechanical vec tors o f thi s dis eas e entity (Plowright 1956; Vandemaele 1961; Mac- Adam 1964a ). The transmission of zoospores by flies has also been shown to occur (Roberts 1963a; MacAdam 1964a ; Richard and Pier 1966 ; Robens and Graham 1966). In experiments with rabbit s both Musca domeSlica and Stomoxys ca!citrarn were implicated {Richard and Pier 1 966 J. In this case three Ixodidae parasites were recovered. Since Boophilus which was the most abundam, is a one-host tick, its potential as a vector wou ld be limited. The three-host ticks, Amblyomma and Rhipicephalus were not present in large enough numb ers as to be significant in th e dis - seminat ion of the disease. The distribution of the initial les ions, being dorsally over the muzzle, head and neck also indicates the importance o f a flying vector rather than ticks. By virtue of their abundance th e biting flies lipoptena paradoxa must be considered important vectors and one of the most significant epizootiological factors of this o utbreak . A well- kn own epizootiological co ncept is that di sease transmission is usually in direct proportion to the density of susceptible individual s. The 26 roan antelope inside the Camp provided a density figure of one anima l per 0,1 km 2 as opposed to one an imal per 14 ,5 km 2 for com- parable habitat outside. The position for the sable antelope is even more dramatic, there bing o ne animal per 0,05 km 2 within the Camp and very few sedentary animals in that particular habitat outside. Even th e most favourable sab le amelope habitat in the K.N. P. does not exceed more tha n one anima l per 3,6 km 2 (S. C. J J o ubert, pm . comm . ). This means that both species are lumped together in a restricted space (2,56 km 2) in densit ies which far exceed those for their free-ra nging com peers in the K.N.P. and must therefore. under the specific circumstances, be re- II garded as abnonnally high densities. Density and probably an associated higher a rthropo d incidence are some factors at variance between the two populations in the same habitat inside and outside the Camp. Free- roaming individuals (part icul arl y calves) are also in a bener position to seek. o ut areas of shoTt grass during periods of heavy precipitation, and thus· escape from conditions which are favourable for the development of this di sease. The failure o f finding infection outside might therefore be regarded as significant in this context. The importance o f density as an epizootiological factor is further stressed by findings to th e elTect that the u-ansmi ssio n of dennatophilosi.s ca n occur by contact between sheep, especially if th ey are wet (Ie Ri che 1968). The behavio ur pauern of young roan and sable calves also afford amp le op portuni ty o f contact between members of a herd. On this aspectJouben (970) wrote : "Certainly one of the maj or characteristics in th e compositio n o f the roan herd is the dose relationship betwee n the young animals and especially those of the same age group. Young roan genera ll y associated together in a closely knit unit o r nursery in the close proximity of one o r m o re of the adult cows, or at times even seek the co mpan y of the herd bull" . " Q.uite frequently even the very young calves interlude the wild running by co nfronting one another o n their knees and after a few seconds of playful butting with their foreheads and push- ing they again jump up and co mmence running around. These play- fights may be repeated several times between different members during each 'play-session '." This butting behaviour sho uld provide ideal opport unity for transm ission o f zoospores to take place. This theory is funher corroborated b y th e fact that the earliest lesio ns were seen on the forehead and around the eyes. Disease manifesta tio ns in roa n and sable calves were very similar to th at which is frequently see n in domesticated stock. Without chemothe- rapeutic interference dea th wo uld undoubtedly have occurred in a hi gh percentage of a ffected an ima ls and probably was the ca use of death of two calves. an occurrence which initiated the investiga tio n. The efficacy o f therapy, as instituted. was further proven by a complete cure after a single treatment. Ac4nowltdgemtnts The assistance rend ered during capturing and treatment operations by Mr L. E. van Rooye n, Senior Game Ranger. Kruger National Park, and Mr P. J. L. Bro nkhorst, Warden, Mountain Zebra National Park. is gra tefully acknow ledged. 12 REFERENCES AUSTWICK. P. K. C. 1969. Mycotic infections. I n Mc DIARMID, A. (ed ), 1969 . Diseases in freeliving wild animals. Symp. z.ool. Soc. Land. 24 :249-271. The Zoo logical Society of London, London: Academic Press. 8ASSON, P. A. and]. M. HOFMEYR. 197 3. Mortalities associated with wildlife capture operations. In YOUNG E. (ed. ), 1973 . The capture and care of wild anima ls. 15 1-160. 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