Examination of wild mammals as a potential reservoir for "T. rhodesiense"

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1 Exmintion of wild mmmls s potentil reservoir for "T. rhodesiense" Objekttyp: Chpter Zeitschrift: Act Tropic Bnd (Jhr): 28 (1971) Heft 3 PDF erstellt m: Nutzungsbedingungen Die ETH-Bibliothek ist Anbieterin der digitlisierten Zeitschriften. Sie besitzt keine Urheberrechte n den Inhlten der Zeitschriften. Die Rechte liegen in der Regel bei den Herusgebern. Die uf der Plttform e-periodic veröffentlichten Dokumente stehen für nicht-kommerzielle Zwecke in Lehre und Forschung sowie für die privte Nutzung frei zur Verfügung. Einzelne Dteien oder Ausdrucke us diesem Angebot können zusmmen mit diesen Nutzungsbedingungen und den korrekten Herkunftsbezeichnungen weitergegeben werden. Ds Veröffentlichen von Bildern in Print- und Online-Publiktionen ist nur mit vorheriger Genehmigung der Rechteinhber erlubt. Die systemtische Speicherung von Teilen des elektronischen Angebots uf nderen Servern bedrf ebenflls des schriftlichen Einverständnisses der Rechteinhber. Hftungsusschluss Alle Angben erfolgen ohne Gewähr für Vollständigkeit oder Richtigkeit. Es wird keine Hftung übernommen für Schäden durch die Verwendung von Informtionen us diesem Online-Angebot oder durch ds Fehlen von Informtionen. Dies gilt uch für Inhlte Dritter, die über dieses Angebot zugänglich sind. Ein Dienst der ETH-Bibliothek ETH Zürich, Rämistrsse 11, 892 Zürich, Schweiz,

2 Est Africn Trypnosomisis Reserch Orgniztion, Tororo, nd Swiss Tropicl Institute, Bsle Sleeping Sickness Survey in Musom District, Tnzni IV. Exmintion of Wild Mmmls s Potentil Reservoir for T. rhodesiense R. Geigy1, P.M. Mwmbu2 nd M. Kuffmnn1 Abstrct The incidence of trypnosomisis ws investigted in 115 mmmls belonging to 13 species. Twelve strins of T. brucei subgroup were isolted; 2 from hyen, 5 from lion, 1 from wrthog, 1 from wterbuck nd 3 from hrtebeest. Five strins of these showed positive rection with the BUT nd re suggestive of T. rhodesiense. Further investigtions re necessry to confirm the identity of the trypnosomes. Introduction During the survey 115 wild mmmls, belonging to 13 species were exmined in 6 different res; 4 within the Serengeti Ntionl Prk, 1 just long the Prk boundry ner Kirwir nd 1 in the Ikom gme reserve (cf. mp nd Tble 8; for vegettion nd gme distribution cf. prt II, Tble 8 nd Fig. 5, p. 19). Most nimls were shot, but 8 lions nd 3 hyens were drted with trnquillizers (Sernyln or Succinylcholin), 1 lion cub ws cught live nd lter relesed. Mteril nd Methods Isoltion of trypnosomes From the nimls tht were shot blood ws collected s soon s possible fter deth, whenever possible by crdic puncture, otherwise from the severed neck, or in the cse of the drted nimls, by venous puncture. Rts not being vilble in sufficient numbers, between 7 to 1 mice were inoculted intrperitonelly. Two methods were then used for the first 7 mmmls. Two mice were inoculted with.5 to 1 ml of whole blood, the rest with blood diluted 4 :1 with sodium citrte 3.8 % (1 to 1.5 ml per mouse). For the lst 45 mmmls only citrte blood ws used for inocultion. In the whole, bout 94 mice were used. Surviving mice were exmined repetedly by wet preprtion up to 4 to 8 weeks fter inocultion. As soon s mouse becme hevily Swiss Tropicl Institute, Bsle, Switzerlnd. E.A.T.R.O., Tororo, Ugnd.

3 212 Ad Tropic XXVIII, 3, Epidemiology infected with either T. brucei subgroup or T. congolense stbiltes were mde using the E.A.T.R.O. stndrd technique nd preserved in liquid nitrogen; sometimes second stbilte ws mde fter further pssge in mice. All T. brucei subgroup strins were lter submitted to the "Blood Incubtion Infectivity Test" (BUT) (Rickmn & Robson 197) for the differentition between T. brucei nd T. rhodesiense strins. For ddi tionl exmintion, severl thick nd thin films were mde direct from the gme nimls nd sometimes lso with the rest of the citrted blood. A few trils with 1 hyen, 1 lion, nd 3 topi were mde with the hemtocrit centrifuge technique (HCT) (Woo 197). About hlf the inoculted mice were lso exmined in this wy before being destroyed t the end of the experiment (Woo & Kuffmnn 1971). An utopsy ws performed on most of the killed nimls by Dr. Lossos (E.A.T.R.O.) nd/or Mr. Burton Gwmk (S.R.I.) nd specimens preserved for lter histopthologicl exmintion. Results The overll infection rte for trypnosomes including ll findings proved tobe 38.2 >/. Tble 8. Description of the 6 * different res in centrl nd western Serengeti Ntionl Prk where 115 nimls belonging to 13 species hve been drted or shot (cf. mp p. 19) Are Description Approx. distnce of re centre from Bngi A long Prk boundry N/E Kirwir Reserch Sttion 38 miles B Mwnz Rod, north Orngi River Junction 18 miles C Tringle between Trck Bngi-Mwnz Rod nd 6 miles Bngi-Ikom Rod (round Retim Hippo Pool) D Tringle between Bngi-Kilimfedh south of 3.5 miles Mngi River E Bngi-Ikom Gte Rod, minly estwrds long 1 miles Prk boundry F Ikom controlled shooting re 8 miles est Ikom Fort * A single lion cub ws cught live nd returned south of Seroner (SS).

4 IV. Sleeping Sickness Survey in Tnzni 213 Six strins of T. brucei subgroup, 12 of T. congolense nd 6 mixed T. brucei-congolense cme up in mice. Thirteen other infections of T. vi vx (4 mixed with T. brucei subgroup or T. congolense) nd 11 (T. un identified) were found in thick nd thin films. A further T.? ws de tected by the hemtocrit centrifuge technique in one of the 3 topi Tble 9. Distribution of exmined nd infected wild nimls Are Animls Isolted in mice Found in blood films only Animls exmined brucei congol. b c vivx vb or c? infected A B C D E * 19 F SS 1 Totl % * In one cse HCT only. Tble 1. Incidence of Trypnosomisis found in wild mmmls Serengeti Ntionl Prk nd Ikom Fort Controlled shooting Are Species No ex No in T. brucei T. con T. vivx T.? mined fected group golense Crocut crocut Pnther leo Equus burchelli Phcochoerus ethiopicus Trgelphus scriptus Kobus defss Redunc redunc Alcelphus buselphus Connochetes turinus Dmliscus korrigum Aepyceros melmpus Gzell grnii Gzell thomsonii species All strins of T. brucei group s well s T. congolense cme up in mice. T.?: only very few bdly preserved trypnosomes were found.

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7 216 Ad Tropic XXVIII, 3, Epidemiology exmined. Where the dignosis is put down s T.?, only one or two bdly preserved forms were seen. In Tble 9 the results re clssified ccording to their distribution over the 6 res exmined. T. brucei subgroup ws found in re C, E nd F, T. congolense in B, C, E nd F nd T. vivx in B, C, D nd E. In re A only three unidentified infections were detected. The highest infection rte ws found in re E, where 19 out of 24 nimls showed detectble prsitemi, i.e. 75% comprising 1 of the 12 T. brucei subgroup infections. Tble 1 shows the distribution of the trypnosome strins found in the 13 species of mmmls exmined. Tble 11 contins the detiled dt of ech niml showing trypno somes, such s strins isolted nd preserved in liquid nitrogen s well s ll the findings from thick nd thin films nd HCT. The most interesting result is the high incidence of T. brucei subgroup nd T. congolense in lion nd spotted hyen; 7 of the 12 strins of the former were isolted from these two species of mmmls, of which ll but one niml hrboured either one or the other or both prsites. The negtive lion ws young cub, bout three months old nd prob bly to young to develop ptent infection. The 12 T. brucei subgroup strins were exmined by the BUT, using fresh humn blood for ech test nd incubting for 5 hours. stbiltes from the first pssge in Eleven strins were vilble s mice, the lst one (hrtebeest 42) from pssge two only. The results re given in Tble 12. One hyen, 2 lions, 1 wterbuck nd 1 hrte beest gve positive results, i.e. rected like T. rhodesiense. Up to now the strins were tested over 1 to 1 mice pssges (the work is still going on). The strin isolted from wterbuck 82 (stbilte E.A.T.R.O. 1836) gve consistently positive results over mouse-pssge 2 to 9, recting exctly s the T. rhodesiense strins isolted from mn nd used s controls. Eight of the 9 known T. rhodesiense strins were isolted from ptients t E.A.T.R.O., the lst one in the Serengeti Ntionl Prk (stbilte of third pssge mde by E.A.T.R.O.). In 1 cse we strted with stbilte E.A.T.R.O. 931, mde from met cyclic forms fter glossin-pssge. As regrds the other four strins, BUT frequently gve positive, sometimes negtive results. Three times n erly test ws negtive, while lter test crried out with mice from the sme pssge becme positive. In the cse of hyen 71 (E.A.T.R.O. 1857) nother series of tests ws crried out over 9 pssges, strting from second cpillry tube. The BUT ws then negtive throughout. These results re difficult to interpret, s Rickmn & Robson (197) found tht ech strin they tested ws lwys negtive or lwys positive. But on the other hnd, in their study never more thn 6 tests were crried out on ny one strin, wheres in the present study be-

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9 218 Ad Tropic XXVIII, 3, Epidemiology Tble 13. Other prsites found in thick nd thin films Host Number Bbesi Heptozoon Borreli Micro exmined nuttlli filri theileri Spotted hyen Lion Zebr * Wrthog Bushbuck 2 2 Wterbuck 1 1 3* Reedbuck Wildebeest 1 5 Hrtebeest Topi 11 7 Impl Grnt's gzelle 2 Thomson's gzelle Totl * With sheth. Tble 14. Mice control sheet lion 6 (16) 16 Dys fter inocultion Lion?Mouse - dult wet preprtion HCT () 73 () V) () 731 () () 732 () () () () 733 () () 734 () () 735 () () () () 736 () () () 9 () hemtocrit tube broken. () 1-3 trypnosomes seen in whole preprtion or tube.

10 IV. Sleeping Sickness Survey in Tnzni 219 tween 8 nd 18 tests were undertken over 6 to 8 pssges on the positive-negtive strins. One explntion might be tht in these cses we hd mixed popultion of T. brucei-t. rhodesiense. The strins giv ing positive results with BUT will be tested on volunteers for ptho genicity for mn. In contrst to the findings of Bker et l. (1967), no T. brucei sub group or T. congolense were found in the 1 wildebeest exmined. This my be due to the fct tht our wildebeest belonged to migrting herds, wheres in the erlier survey resident herds hd been exmined. While serching for trypnosomes in thick nd thin films, number of other prsites were found. A preliminry list is given in Tble 13. Discussion In contrst to other uthors, we never found cse of T. congolense in thick or thin films which did not pper in mice s well. Two fctors offer themselves to explin this discrepncy. By inoculting 6 to 1 mice insted of two only, the chnces of isolting T. congolense in crese considerbly, since frequently only 1 to 3 out of up to 1 mice inoculted becme positive (cf. Tble 11). Secondly, T. congolense my produce only very feeble nd fleeting infection in lbortory nimls s hppened on this occsion in the cse of lion 6 (16) nd hyen 3 (99) nd 4 (13). Eight mice were inoculted from lion 6 (16), 2 of them showed very few trypnosomes on dy 6, nother 3 cme up on dy 7, 4 were still positive on dy 8, but on dys 1, 12, 14, 15, 2 nd 24 not single trypnosome ws spotted in wet preprtions. After tht HCT ws used on the whole series nd very few forms were found in 6 of the 8 mice (cf. Tble 7). From hyen 3 (99) 1 mice were inoculted, 1 of them showed few trypnosomes on dy 1 only, then ll controls remined negtive up to dy 21. On dy 29 the series ws tested by HCT nd 2 mice found to be positive, one even showing high prsitemi; the strin hving been identified s T. congolense ws preserved in liquid nitro gen. Only in one of these three cses (lion 16) T. congolense ws found in thin film (cf. Tble 11). Two mice out of ten nd one out of ten inoculted with the blood of lion 14 nd 15, respectively, developed T. brucei subgroup infec tions fter 6 to 9 dys. All the other mice remined negtive by wet preprtion exmintion. On dy 26, these mice were exmined by HCT: 3 mice of the former nd 5 of the ltter showed feeble infec tion with T. congolense (Woo & Kuffmnn 1971). It seems essentil tht enough mice re inoculted, s it hppened frequently tht even out of 1 mice only 1 or 2 produced detectble

11 22 Ad Tropic XXVIII, 3, Epidemiology prsitemi (cf. Tble 11). In ddition, one cn sometimes seprte mixed infections by using sufficient number of mice. As in the cse of other similr surveys, the niml species found to be the fvourite hosts for the glossin species present (here minly G. swynnertoni) re not t ll the sme s the ones serving s hosts for the glossin-trnsmitted trypnosomes (cf. prt II). Furthermore, the "fly" nd the "gme" res in generl do not coincide with the excep tion of "fly re" 6, which lies in the middle of "gme re" C, nd res 3 nd D, which overlp (cf. mp, prt I, fig. 1). For obvious resons, the res where hunting took plce were mny times the size of the ones where flies were cught. Wherever lions were immobilized with trnquillizers, mny tsetse flies could be observed ner nd round the resting groups or prides of lions, ll the fvourite hosts of tsetse flies being kept t considerble distnce. Exmintion of the drted nimls, specilly the older ones, reveled the presence of mny hippoboscids, bloodsucking species of dipter which hs been sus pected s mens of mechnicl trnsmission of trypnosomes (Bker 1967). The specimens collected were identified by Dr. Oldroyed3 s Hippobosc longipennis, Fbricius 185, species recorded in Afric from lion, leoprd, cheeth, hyen, jckl nd other crni vores. About 2 hippoboscids found on lions were dissected in the lbortory, but no trypnosomes were found in the mouthprts or in the gut. References Bker, J. R. (1967). A review of the role plyed by the hippoboscide (Dipter) s vectors of endoprsites. - J. Prsit. 53, Bker, J. R. et l. (1967). Trypnosomes of wild mmmls in n re northwest of the Serengeti Ntionl Prk, Tnzni. - Z. Tropenmed. Prsit. 18, Rickmn, L. R. & Robson, J. (197). The testing of proven Trypnosom brucei nd T. rhodesiense strins by the blood incubtion infectivity test. - Bull. Wld Hlth Org. 42, Schs, R., Schuer, G. B. & Bker, J. R. (1967). Isoltion of trypnosomes of the T. brucei-group from lion. - Act trop. 24, Woo, P. T. K. (197). The hemtocrit centrifuge technique for the dignosis of Africn trypnosomisis. - Act trop. 27, Woo, P. T. K. & Kuffmnn, M. (1971). The hemtocrit centrifuge technique for the detection of low virulent strins of trypnosomes of the Trypnosom congolense sub-group. - Act trop. 28, in press. Young, A. S. (1968). SRI report, unpublished. 3 British Museum, London.