AN OUTBREAK OF DERMATOPHILOSIS IN SABLE HIPPOTRAGUS NIGER AND ROAN HIPPOTRAGUS EQ . UINUS IN THE KRUGER NATIONAL PARK "

Ab5tracl A severe skin disease diagnosed as dennatophilosis took on alarming proportions in roan antelope Hippotragus equinus and sable antelope Hippotragw niger herds, which were kept in a 256 ha enclosure in the Kruger National Park, Republic of South Africa. Only calves were effected. Numerous DmnatophilUl organisms were identified in skin biopsies taken from affected areas and examined histologically. Complete recovery followed a single treatment of intramuscular injections of a combination of a long-acting penicillin and streptomycin 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.


Introduction
The distribution of the disease entity known as dermatophilosis (cutaneous streptothricosis, senkobo disease, mycotic dennatilisl 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 African 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 Gau lle thormorn• (MacKenzie and Simpson 1964) and a zebra Equus sp.(Green 1960) have been found to be mildly infected.In temperate regions the disease has been reponed from the white-tailed deer Odocoilew virginianw (Dean, Gordon, Severinghaus, Kroll and Reilly 1961;Kistner, Sholts and Green 1970), a cottontail rabbit Sylvilagus jloridanw (Shotts and Kistner 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 (according 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 careless 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 througho 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 groups could be released periodically to augment the natural populatio n, it was decided to erect an inviolate enclosure of 256 ha in the most favourable roan habitat in the northern district o f the K.N .P. This enclosure is hereafter referred to as the Camp.A nucleus herd of 10 roan were released in the Camp without mishap in 1967 (Pienaar 1968 ;Jo ubert 1970).
After promising res ults were achieved initially, 13 sab le antelope HippolragUJ niger, also a rare species in South Africa, were placed in the sa me enclosure during August 1969 and May 1970.
The respective nucleus herds did exceedingly well initially.The roan antelope herd, however, suffered a severe setback in 1970 when 15 out of a total o f 27 animals died from anthrax (unpublished data, de Vos).
In spite of mortali ty of unknown aetiology which the young calves of both species suffered sporad ically, the numbers again increased to 48 for sable and 26 for roan antelope at the beginning of March 1974 .Shortly thereafter, however, two deaths among young sable antelope ca lves occurred but due to interfere nce by scavenger birds no worthwhile specimens for diagnosis were available.It was decided to tho roughly examine rema ining animals in the Camp in an attempt to detemline the causes of 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 the vehicle.A pair of 10 x 50 binoculars aided in the close'• examination o f individuals.Affected animals were subsequently caught by th e drug immobilization technique.A Pa lmer Cap-C hur gas-po~c red rifle was used to propel two ml capacity darts or projectill' synnges.
To lessen the disturbance factor the recumbent animals were saken by vehicle to a properly equipped po int of operations o n the periphery of the Camp for closer examination, sampling and treaonent.
Skin biopsies were taken fro m the worst affected areas of each individua l and preserved in Milio nig's 10% buffered fonnalin .In addition deep skin scrapings were collected in a 50% glycerine/alco hol solution.These specimens were processed and examined at a later date.The formalin-fixed tissues were prepared in a routine manner for light microscopy and stained with haematoxylin and eosin (HE), Giemsas and Gram's stains and the periodic acid Schiff (PAS ) reaction.
Treated animals were marked by hairclipping, every individual having its own distinct and easily recognizable identificatio n mark •for fUlUre reference.After resuscitatio n the animals were released in the immediate vicinity of the herd .During 15 to 20 April 1974 12 affected animals were caught and trea ted in this manner.
In order to assess the course of the disease without chemotherapeutic s interference, the least 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 individuals was caught and re-examined to determine the reaction to therapy.
To detennine whether infection occurred in the immediate surroundings of the Camp, the area was surveyed intensively by means of binoculars.
The comparative abundance of ticks inside and outside the Camp was subjectively assessed by merely walking through the veld in the respe<:tive areas.The amount of ticks attached to the person was taken as an indication of abundance.

Climate
Data were obtained from the meteorological station at the Shingwedzi Rest Camp, situated 40 k.m to the south of the enclosure.

Drugs
The immobi lizing drugs and antidote used were : ElorphiM hydrochloride, M99 1 was used as the basic immobilizing agent (Pienaar 1974 ).AzaperoM, R1929' was used as a neuroleptic together with the M99 in the dan combinatio ns (Pienaar 1974 ).Nalorphine hydrobrol."lide,uthidrone' was used for its ' properties to antagonize the narcotic effects of morphine or a morphine derivative such as M99 (Pienaar 1974 ).
For thera py o f the skin condition , associated debility and stress, a series of drugs and combinations were used .The faculties for which the drug was choosen, are mentio ned briefly in each case.
Thioctic acid {Tioctan)4 was administered for liver invigoration, detoxification and metabolic improvement.ProcaiM penicillin G and benetluzmiM penidlfin (Compropen)5 was administered in combination with dihydrostreptomycin (D iStrep)6 for its known synergistic action against D .congolemis (Roberts 1967;Smith and Cordes 1972).Selenium-Vitamin E (BO-SElf was administered for it 's beneficial effect on capture myopahty as cleimed by Basson 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}) Ltd. hexachloride, S.H.C. diluted in water to a concentration of 0,0396 of the gamma isomer was used as a wash for its known paraciticidal effects and iu claimed beneficial effects o n the course of dermatophilosis (Plowright 1956).A dermatological preparation, applied topically was made up of: "Healing oi l"9, co ntaining 33,396 vegetable oil, 58,996 oleo resins and 0,596 gennicidal agent as the basis with copper JUlphaLe B.P. added to make 5% of the fina l solution.Copper sulphate was used for its useful antiseptic and potent fungicida l properties.

Environmental
Geographica lly the Camp is situated in the northern region of the K. N. P. and occupies a 1,6 km area to the north and south of the 22<'47' latitude south a nd 3 1°15' longitude east lines respectively.As is typica l for the rest of the region the area is rather flat , with an altitude of about 390 m above sea level.The area co nsists mainly of a heavy '" '" ...    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 especia l\y lush during the lime of the disease outbreak.For the greater pan of the Camp the grass exceeded the sho ulder height of the younger, or affected animals.As depicted by Fig. 1, exceptionally heavy rains were experienced during the season preceding the disease outbreak.Precipitation in the form of heavy dew further intensified and prolonged exposure to moisture.
The biting ny lipoptena paradoxa was panicularly abundant and when wo rking 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 utside the Camp.

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 the aid of 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 , some being obvio usly in the early and others in more advanced stages of the disease.Debilitation clearly paralleled the progressive stages of infection .The more severely infected individuals showed a droopiness of the head and ears and frequently shook the ir heads as if the lesions were irritant.They often lagged behind the rest of the herd .Mild lachrymation was shown by the most severely infected individuals.
Binocular examination of animals outside the Camp for infection was also carried 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 calves were caught 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 intramuscalar deposition of the drugs by Cap-Chur dart.This was, however, 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 minutes and joined the herd shortly afterwards.No fatalities occurred.

GrOjj Appearanu
The sk.in condition was an exudative 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 exudate 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 could be removed more easily and in some instances were o nly held in place by penetrating hairs.
The variety of lesions.or various stages of infectivity, made it possible to follow the sequence of development of the les ions.In the earliest stage • 6 Fig .4. Derma tophi los i s.   on ly the rorehead and immediate VICIni£}, or the eyes were atlected.
Lesions 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 encrustatio ns o r the dorsal aspects or the body, the lateral rib cage behind the elbow, the sternal aspect and lower parts or the legs.In this case the hair or the rest o r the body were unnaturally ereCl and on palpation revealed roughening or the skin surface due to numerous small (pea-size) isolated wart-li ke elevations.Nu merous immature srages or Boophilw ticks were round o n the animals, some even bei ng imbedded in the lesion encrustations.A rew Ambl)'omma and Rhipicephalw ticks were also round, mostly confined to the anal region.

Hijtopathologjcalfinding5 and Dtjinitive Diag1loju
Pathological changes were primarily in the epi d ~r mi s and consi sted or acamhos is and piling or cornified epithel ium and exudate on the epidermal surraces in a layered rash ion (Fig. 4. 5, 6 and 7).This layered material contained neutrophils, which in some foci were concentrated in a pustu la r-like fonnation .Within the exudate organisms were easily seen in HE sta ined sections.They were most plentiful around, but not invading hair sharts (Fig. 5) and in foci containing large numbers of inflamatol)' cells.Organisms grew in a mycelia -like rashion (Fig. 6) and the growth fonnalion was divided both horizontally and longitudinally 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 histologically 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 revea led drastic and a clearcut improvement of previously affected individuals.This was further borne out by catching and closely examining one of the ca lves which was judged to be severely infected prior to treatment 12 days earlier.Scab fonnation had stopped and the sk in was dl)' and pliable.The overall impression which was ga ined was that the a nimal was on its way 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, sternum and legs.
Treatment was instituted at t.his time.As witnessed a month later al animals showed a completc clinical recovel)'.

DiJCWJion and ConciUJiom
The gross skin lesions of dennatophilosis are essentially thf: same in all animal species (Sm ith , J o nes and Hunt 1972) and those seen in the roan and sable calves of this report confonn with those which have been described.The constant finding of Dtrmatophiltu organisms in skin lesions therefore warranted a diagnosis of dermatophilosis.
The fungal-like appearance of D. congolensiJ has led to names for the disease such as mycolic dermatitis and cutaneous streptothricosis. Cordon (1964) disproved its relationship with fungi and regarded the above na mes as misleading implying rreaUflent should be antifungal instead of antibacteria l.Roberts (1967 ) suggested " dennatoph ilus infections" be used for the disease and Stewart ( 19 72) Slates the term "dennatophilosis" is equally explicab le.Jubb and Kennedy (1970) expressed the opinion that the older entrenched names, Le. cutaneous streptothricos is in ca ttle, mycotoc dennatitis in sheep and strawberry fOOtrOl in sheep be retained but recent reports of the disease have favoured derma lophi losis.
Alth ough the epizootiologic pattern of dennatop hilosis is not completely unders tood, some fa ctors contributing to dissemination of this disease are known .Organisms o f the genus Dtrma/.()philUJundergo fragmentation of the mycelia as a result o f multidimensio nal division and give rise to motile zoospores (Gordon and Edwards 1963;Cordon 1964 ;Roberts 1967).The reselVoir of D. congoleruiJ in nature is, however, unknown.Attempts to isolate it from soil have been unsuccessful (Roberts 1963a ;Kaplan and J ohnston 1966).Roberts (1967) mainlains tha t chronica lly affected individuals are probab ly the o rganism's chief means of survival with in a nock or herd during donna m periods.There is also evidence that the micro-orga nism concerned leads a saprophytic life on the skin and that it is not until the equilibrium be[Ween the parasite and host is disturbed by extraneous facto rs that it becomes a true pathogen (Cordon 1964).The micro-organism which gave rise to the present outbreak must therefore have originated from a biological carrier within the Camp.
There has been a rather consistem association between wet conditions or hum idity a nd infectio n (Chodnik 1956;Plowright 1956;Scarnell 1961; Ie Riche 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 or prolonged wetting of the skin apparentl y results in emulsification and disruption of the sebaceo us film (Roberts 1963b ;Roberts and Graham 1966) as well as maceration of the stratum corneum , which then becomes more penneable to irritant substances (Suskind and Ishihara 1965) and probably more susceptible to disturbance by mechanical agents (Roberts 1967).
As depicted by Figure I exceptionally heavy rains were experienced during the season preceding the disease OUlbreak.Wet conditions were furt her augmented by a high humidity with regular nightly precipitatio ns in the form of heavy dew which nOl o nly dampened individua ls dose to the ground but also thoroughly moistened the t.all grass cover.This provided almost continuo us moist cond itions for the young animals and must be considered partially respo nsible for the dramatic differential morbidity in which the calves were exclusively affected.However, 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 born with an incomplete sebaceous film that does not become fully protective for a period varying from a few days to five or six weeks.This should not be a faclOr in the present outbreak as the 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 suggest ing trans fer by insects , or on the lips and legs suggesting transfer via the pasture (Roberts 196 7).In cattle in Africa the disease is closely associated with tick infestation, and the lesions develop mainly in those ventra l areas of the body most heavily infested with ticks (Plowright 1956;MacAdam 1964b).Ticks of the genera Amblyomma, Boophilus, Haemaphysalis, Hyalomma, Ixodes and Rhipicephalus have been incriminated as mechanical vectors o f thi s disease 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 rabbits both Musca domeSlica and Stomoxys ca!citrarn were implicated {Richard and Pier 1 966J.
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 would be limited.The three-host ticks, Amblyomma and Rhipicephalus were not present in large enough numbers as to be significant in th e disseminat 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 the biting flies lipoptena paradoxa must be considered important vectors and one of the most significant epizootiological factors of this o utbreak .
A well-known epizootiological co ncept is that disease 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 animal per 14,5 km 2 for comparable 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 the 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 densities which far exceed those for their free-ra nging compeers in the K.N.P. and must therefore.under the specific circumstances, be re-garded as abnonnally high densities.Density and probably an associated higher a rthropod incidence are some factors at variance between the two populations in the same habitat inside and outside the Camp.Freeroaming individuals (particularly calves) are also in a bener position to seek.out areas of shoTt grass during periods of heavy precipitation, and thus• escape from conditions which are favourable for the development of this disease.The failure of finding infection outside might therefore be regarded as significant in this context.
The importance of density as an epizootiological factor is further stressed by findings to the elTect that the u-ansmissio n of dennatophilosi.s can occur by contact between sheep, especially if they are wet (Ie Riche 1968).The behavio ur pauern of young roan and sable calves also afford ample opportunity of contact between members of a herd.On this aspectJouben (970) wrote : "Certainly one of the maj or characteristics in the compositio n of the roan herd is the dose relationship between the young animals and especially those of the same age group.Young roan generally associated together in a closely knit unit or nursery in the close proximity of one or more of the adult cows, or at times even seek the company of the herd bull"." Q.uite frequently even the very young calves interlude the wild running by confronting one another on their knees and after a few seconds of playful butting with their foreheads and pushing they again jump up and commence running around.These playfights may be repeated several times between different members during each 'play-session '."This butting behaviour should provide ideal opportunity for transmission o f zoospores to take place.This theory is funher corroborated by the fact that the earliest lesions were seen on the forehead and around the eyes.
Disease manifestatio ns in roan and sable calves were very similar to that which is frequently seen in domesticated stock.Without chemotherapeutic interference death would undoubtedly have occurred in a hi gh percentage of affected anima ls and probably was the cause of death of two calves.an occurrence which initiated the investigatio n.The efficacy of therapy, as instituted.was further proven by a complete cure after a single treatment.

Ac4nowltdgemtnts
The assistance rendered during capturing and treatment operations by Mr L. E. van Rooyen, Senior Game Ranger.Kruger National Park, and Mr P. J. L. Bro nkhorst, Warden, Mountain Zebra National Park. is gratefully acknowledged.

Fig . 1 .
Fig .1. H iSlOgram of the monthly rainfall dislribulion for Shingwedzi Rest C,lJnp, Kruger National Park, during the period of and directly prt•, ced ing the outbreak of dermalOphilosis .Yearly rainfall figures are included li)r comparat ive purposes.

Fig. 3 .
Fig. 3. Derrnatophilosis.sable calf.Patchy lesions around eyes and base orcaI'.Encrusted hair in lesions over the withers.No te capture dart in right hip.Dermatophilosis, sab le calf.Patchy lesions on cars and heavy encrustatiun of mane down to withers.