Symptomatology of some Trypanosomiases of domestic animals

SL\1l'TlL\l.\TOI.O(;y OF StUE THl"1'.\SOS0.\1L\SJo::.; o1: IJ0.\11·:.'-T1<" .\:\1.\1.\l.S.

Ac;utP 1'. i:OII_!JOicuse infection,; \H'l'l' protluc·pcl :1.; I he• rt>sult of the iu_jc•r-tion of '/'. r·on_!;rili'7Lsr• infpdecl blood obtained from infPC'iPtl g-llirw:~ pig-s 01· hu,·int>s. ThP disP:1se i:-; 11shen·cl in hy :111 ele,·ntion of lilt' IPllljJPl'alun•, at times hig·hc>r th:~n HF>O 1:. :~ftpr ^:111 inh·n·al IYhir·h YariPs llllt "·hil'h lll:l_\' lH' :IS short "·' four da\·s. ThP p:~ra:-;iiPs lll<l\' l>e fm111cl in blood S1llt'clr,; ;t.-; parJy :1s ihc· ..J.ih tl:1_\·, hc•ing- found :-;ome\\·h:~l Liter in the glancl iil1lears. ('hnl'1 J of iPllljl<'r:Iilll't' and of SJll!-':lr· exanrination is submitted. l)uring-tlu-• iniii:1l part ol lhP infpc·-

tion there is rlullnPss :llHl clPr'I'PasPtl :ljlJW1itP. J.t inipn·:1ls thP appel iiP i:-; liHll'P or [p,.;,; nonnal :~u<l this c·npric·iou,.; 1wture of 1 hP appetiiP pPrsists until lhP foJ'Ill hf'comc•s eilhPr rhmnic· or JH'l':ln1tP.

The c;oui. i:-; roug-h ancl rh_, .. The-• c·onstitnlionnl dislurlJ:IIIf'E's :~rP nen-'r Yery mm·kNl. hut arE' 1non-• in e'l·idt-nt·P tlm·i11.~· thP PX:Jt·Prhalion:; of temJwr;ILun•. in1proving- •hiring- ihc• n'llli . .;_.;illll,<. The YisilllP nnii'Oll.~

me1nlirnn!'s UI'C·' p:1ler tha11 norliJ;Il. hut ic·leri1· tli . .;l'oloration "'"" 1101 oLsPI'\'<'rl in any of tlw brg-P lllllllhc-•r of ho,·ines expPrin1ented 11·ith.

'l'he pulse is a•·ct-l<'r;tled and I hP rPspir:~i ions, "·hit'h art' shalJm,·. sho\1·

incrpased frequency. 0PdPma a11d Pl'!'-lPsion.; ha1·p not hc•c•n ohsc .. rYed in ilw :ll'lliP •·flsP.-; . • \n PXalntn:il io11 of I Ill' blood c• . .;l;lhli~\ip_-; ddinilt•l_, iltP p1·1'-;pnc·p of an :111ac•mia ;liid, furtllt'I'JIHJI'I', dPh-•r1nint>s lhc· most markc·d •·h:~llg'l'' 1\i;il lll'I'Ur i11 thi . .; di"';ISI'. TIH•rt' i . .; a r:1pid det-re;tsP i11 the• il:tc•lllog·lohin. i1t lilt' n•d prt'•·ipihllt• (rpc\ r·•·ll ,-olu111l'l, arit\ lhP llttlltilt'r of rpd l'i'\1.--. '1'\il' t'Oiitlitioll i\ltJ..; i~ c·~~l'llli;l]\\ lllll' or ^;t r:tpid]_,.

Jll'O<[tH·Pti aii:IP1llia \\·i1\i <I \o,;,.; or l'tlii<Jifitlll, IIOlll'ifh.;t;lllclitlg' ;1 fair hut l';q:t·lt'IOlf,< apJll'liit• a,<:'lll'i;l(t•ti \\·i1h ^:Ill intc•J'Illiffl'lll rP\'1'1'.

('lwd J I illu~ir:ilt•-; iht' t·!Iang<'' clPIPI'tlliiH'd i11 I !It• ldoocl c·oll.-;liltiPill,. Till' hnc•ulog·lohill cil•tc•l'lllin:ilitJn,.; 111 llti . .; 1·a.-p :Ill' illt'llltlplt•i<' hut

"td-Ji<:irnt nrt' n1·:1ilalllr• to indi<·ntc· t h;Ii I liP h<Il'1Jio) .. do1Jirl dPt·n':lsl' ,., IT<''Jiond-; fair]_,. :HTtll'ait-ly ,,·it!i lilt' r!Pt·n•;l.-c' in 1l1P lltllllht•r of rPtl r·Plls :111d iiiP rt>d pn-•ripil:1ie.

,\_, alrP:ttly .-;tnlerl, ,.;ut·h :u·uic· t·;J . .;c>,-; 1111clt-1· r:ll·our:t!J[,. ,.,,nclitioll~

]>:ISS g-r:tdu:dl_,. inio lht• l'l1roni1· 1'111'1J1 of lhc• disc-';I~P. 11·iib al tillle;.; :tll impl'lll't!llll'nt in IIIP •·onditinn and t!IP anaP111ia.

'i'!:P r·l1roni1· forn1 of 'f'. n!II_!Jnlf'nsc infpr·ti11n i~ l'h;nac·tnisPtl l'bic>fh· ll\· tlw PYidPIIt't' of the <llt:tPnlia and the ah.-<eiH'P of thP nton•

:1r·niP. s_,-1-nploms nnlr-~d i11 the prP,·ion:-; form. 'l'hPrl' i~ npp:irPntl~- an Pf]tlilihrinm 1Jetii-PPII thr-• hod_,. n•si,-l:lnr-p antl lh1· p:nasiiPs hut thP PquilihriuuJ is IISII:Iil_,. :II <t lo11· rc·d c·c•ll c·m1nt: not.''' m·•·ut·s in Jll't'- lllllllililln, ala hig-h n•tl t·<•ll I'OIInt. 'l'hi.-- r·hm11i<· fr,rlll 1111dc•r fn,·otll·- ahlr• t·oJlditioll-; 111<1_\'. 011 :11·c·o11111 oi thP IIJbC'I ol' thl' t'qllililll·ium in f:11·out· of lhP pnr:tsitt?s, p;1.-;~ into thP per;H·tdP for111 ot· lllld1'1' Yt'l'_l·

Lll·ou1·;1hit- r·oiulition.-; appro:H·h t\1P st;ilt• llr [Ht'll11111iti1111. r•.g. 11·\tt'll loll;,., 11·hit'h han• apparent[_,. 1111 c'lh-·1'1 011 the Jl:ll·:hill' . .; hri11,!..!· aho111 :Ill iiiiJII'()I'('IllPilf ill I'IJIII\ifitlll allc\1'(-•,-;ll[f i11 <111 Pqlli\il>rilllll 011 <I highl'l' p\;IUI'. ~liJIPrficiaJl,l \\ip 11111.-<f 111;)1'\((•d ,<\ IIIJllOnl.; ,,t· till' I'!JI'IInil' 1'111'111

<11'1' tiiP loss of t'Uiidition. thP dr_,. ,,.11rl'_1 _.;!;in. i.hc· ar·rTic•r:ilr·d pulse•.

the· skllln"· ntpid t'l'.-<pir:tl ion . .;. I ill• tlist I'P·'·' Jli.<Hlcwc·rl l11· c•n•n .-;]ig·ht PXl'l'i ioll ;11111 thP IP111\l'lll'\. for I hP 111<II'i;p.] PX<I('t'!'IJ:tf ioll' <I lid rellli.--sioll.-<

of iiiP ;11·tde form to tli,-a.ppP<Il'. As in th1• <II'lliP for111 oPtlt'III<I <tnd

P_,., ,_

leo~ion~ 11·ere not olJst•n·pcl. Tilt• IIUIIIllPI' of n·d •·pll,.; ;1nd thP l'l'rl prPI'iJlilate uRu:dl.v 1·em<1i11 pral'lil'all\· ~t:~tiOII<IJ'~- :1t <1 lo11· lPYPl.

('lwrt JY illustrates tlw Jrrimar\· fall in lilt• numher ol n·d •·Plls and tlu• rei! prPripitale during· ihP :wuiP stage :~nil the ath1ining· anrl the

252

ll. S. l'Alli\:UI.

maintaining of the ectuililnium during the duonic ::;tag-e. Photo- graphs 1 (a) and (b) of boYine :36% illustrate the a]Jpeara11ce of a chronic case -of T. con.r;olcnse rlist>ase 19 "·eeks after infection. Chart III reprt>sents tht> temperature c·unell of t hi;; boY i ne chning- the <-tC"Ute and dnonic ,;tates, the former rurYes being nbout ten weekfl prior to the lattel'. The comparison of th.e t"·o eurves ilhtKtrates lYell the change.~ in the tempt>rature::; \l·hirh take place when the cli,;ease pasHes into the chronic state. In sheep, ou the other hand, the exaeer- bati.ons ancl remiscrionR of temperahtre are 1·emarJ-:ably pers1Rtent.

The peraeute form 11·hieh is described lnst ~lit .c1c~ount of the appearance of symptom,; n·luch haYe not been note<l m the acute a.ncl ehronw form::; has been proclueed by the exposure, during inele- ment weather, of hoYiueo; in the chronic or acute ;;tates -of the infee- tion. 'fhe change from these ::;tates to the peracute is very rapicl, fm, within a week the condition may pass hom the mo1·e or less non- varying chronic sbte m the preYiously rlescribed acute Rtate, to the peracute form sh011·ing a marked exacerbation of the conllition with the rleYelo_pment of aclcl itional symptoms. ln this peracute form symptoms such as saliYation, lacln_vma.tion nnd pl10tophohi<t nsso- eiatecl "11·i.th ot>clema and aeute kerati.ti~; maY he -obsen-ell. Photo- graphs 2 (a) ancl (b) of boYine 2727 ilhtRtratevtltt> nppeanmce denrl).

Although no local treatment of the eyes "ll·a,; carried ont, the e.re- lt>sions in this case improYeclrapiclly on iht> institution of a irypano- eidal t rea I men t. Recover~·, howeYt>r, "11·a,; not complete on ac:eo llll t of the pen-;istrncP of corneal opacities. It suitable treatment of a hoYine suffering- hom a penu·utP attack i:-; not in,;t itutecl the animal

<lies. For example, lleath Ol'(;\lrred in a hoYine whic-h, ''"hen in .a dnonic ~tnte of the lli.sease "ll·as e.s:posecl to inclement "ll·enther. 'fh1s animal harl noi ]Jl'eYiously been treated. It <liecl one "1\"eek after being- e.s:pose<l. 'l'he try panosomes whir h preYious to expos11rt> were ahl·a;;s rliffieult to finll, he<·ame Yery numerous within a fe"ll· clays. Abnormal forms were frequent espel'iall_1· so in ilw muscle smearR. Later three further bovines were e.s:poKecl. 'l'he~r, hm1·eyer, \\·ere not in the chronJe

~;tate for they were placecl ont immecliately after being infected. These boYines, whose munberR "·ert> 8416, 3508 ancl 3520, lliecl clurinp;

the lOth, 5th ancl 9th weeks after the elate of infection which wa,;

the day of commencement of e.s:posurt>. Before allcl after cleath irypanosomes were Yel·)· frequent in the hloo<l c;mem·R. Curson (1928), 11 ho conrlucterl mnny of his obserYat ion~ in tht> :fit>lcl, records oe<lemn ancl corneal npacitit>R in hoth tht> artificial ancl nahnal caRt>,; of T. 1'011_r;ol!'me inft>dion in hoYinrs. Hornhy ("192!J) sur]trising-l)· has not obst>lTPcl eitht>r oeriema or t>Ye-lesions in this rliRt>ase. ITe sl:1tes ibai " the lliseast> (1'. ln'ttr·ci infect ion) io \l·hil·h it giYP,; ri:;e i;; a~KO­

l'iatecl "·itlt o!'rlcma !.·cmtitis, sleeping- fiickne,;:;, iu utero infedioll, etc, 'l'his is not the case ,,·ith T. ron.r;olcnse disease ". He then formulates the theory that " T. t·o''.r;oll'nse i::; essent iall)· a hloocl parn- site ancl 1'. con.r;olensr cliKt>ase is essentiall~- an anaemia ''. In il1e peracute case:=; at this Im;tihdion there ,,.t>re no complicai ing diseases ancl in those ca:;es h eated rapi<l improYemeni set in. SiiJ1ilar all(l even more arlY:mcecl eye-lt>sions haYe been observed togt>tht>r with local generalised oedema in T. rou.r;olrnsr infection of clogs. Furtht>rmore, tlw conrlition in T. brucP-i infection of horses is in manv caseR charac- teriRecl by the anaemia ,,·it It the a hRenre of oerlema a~Hl eye-lee; ions.

253

SY:I.U'TO~L\'1'0 LOGY OF SO :II" T I( 11'.\::\0SO:II IA '-'ES 0 I' J JO~J I':STH' .\::\ J ~J ALS ·

From the clec;niptiom; giYen nboYe of the three ~tatet> of T. r·un- golense illfechon of hoYines it "·ill be t>een that the maJOr commmJ ::;ymptom i::; the U!JUBmia \Yhich is al1n1ys pref'ent in the JJl feett>cl bm·ines llt'OYi<lecl that the hoYine has not attai11ed the state of pre- muniii.on. 'l'he hoYine reg-ulnrl:'i- show;; a low 1·ecl C'f'll e·ount, reel 1neei pii ate aml b aemog-lo hi n c·o nte u t. 'l'hese ch a ng-t>s "·f'rf' noted hy the \\Titt>r in all tlw case;; exnmi11ecl, wheiht>r l'eracute, acute. or chronic. Common also to the tlnee types of '!'. con.r;ole11se infection i_, the negative fin eli ng- or a l1tie n!'e of nnn ked chang-eR in t ht> reel c·ells.

It was early cletermi11ecl b5· the 1n·iter that except for a ,;light aJiiso- cytosis there "·erE' no other changt>o; i11 the reil ct>lb Huch as are usually associatecl "·ith the presence of anaemia in hoYines. Pob·- ehronw;:;ia, pu net a tt> ha,;ophili a ;1 n el IWnnoblasts \"\·ere not foun cl i11 a single case. 'l'l1ese points haYe been rt>conle1l hy l'arl;i11 nnd Ilomln

(]9!~0). DinC'e then the 1niter h;J,.; ha<l no rea"ou to (·hung·e thi~ ohseJ·- Yation ns far a:-;'/'. cvn.!J/olrnse infection of boYint", is C'OIIcen1ed.

Of inte1·e"t "·hen the symptoms of ihe 1lisea;:;e are uncler cm1sidera- tio11 is tl1e ra]Jicl improvement of the anaemiu u~ a result of the institution of treatment "·ith antimoc;aJl. It is noi. eye11 neeessary that the ireaiment he c;ufficientl_,. efficient to prodll!'e st!•J·ili:~.ation to bring- about complete 1·ecoYer~· hom the anaemia. Then-• mig·ht, for example, rec;1dt a retm·11 to the original reel c-ell c·ouni and i he orig-i11al reel cell precipitate a ncl the haemoglo hi n might return to 11 ormal not11·ithstanrliug- i hat the trypanosome can si ill be founcl in blood smem·s. And fllrthennore, the hoYine can retain this state of hloo!l normality nohYi.thstalHli ng exposure to >Yeather ,;ufficiently inclement to c·ause death, in, fm example, chr-onic cases. It is, in other words, in a state of premunition, the commonly nuders toorl im m unit.\· as a ppliecl to protozoa 1 disease;:;.

In calves T. cun.r;olense infection pro1luce,; as t>eYere ill-effeds as in a1lult boYines. Photog-raph 3 i,; submitted herewith as an illustJ-ation of the infecti-on in a calf >Yhich "·as horn of a co\\· "·hich was not .affef'iecl with the cli.,;ease. 'l'his photograph >Yas taken 11 weeks after the injection of 1'. conuolensc. In another calf, "·hic-l1 '"a"

born of a cow in a premm1ise<l :;tate, the infeetion 11·ith T. e·onqolensc of the same strain <1,; that with whieh ihe cow was infecte(l did not pro<luce as HeYere ill-eHeds as in the preYious ca~e. Photogrnph 4 of this calf is snhm i tte<l. Furl her IYOl'k woulcl he uecess;u\- to cletPnnine whethe1· n1h·es horu of JH'<'Illnllisecl hoYines haYe or n•;·eiYe throug-h the milk 'ome ;;lig-ht 1·esistan1:e to iufedion 11·iih the lllll<l~ite. 'l'he hehaYiour, in aclclition to ihe s~·pmtoms, of the t11·o (·Hh-es "·as 1liffert>nt for the calf of the premmJise<l co11· was li1·el.\, 1d1ilP the oiher showecl m<ukeel llE'prPssion. <\lthong·h onl.Y two cah·es ""<'rP u,.;ed for this c·omJ~<~riwn, th(' re;;uli;; are soJU\Yhai ~ug-g-etiti,·e an<l affonl a po,;sihle e-"pbnaiion of why, in ,:ome pad,;, certain he!'(],; <"<Ill be lllaintaine1l in areas \\·here they are coustantly eXJ)()Sell i.o inL•ct ion

"tth tr~·pano,omes. The presPn!'e of some slighi re,;i.-iance in !'ahes horn of infpdecl co\\·,; mig-hi inne;1se their chanc·e,; of ,;un-i.Yal.

(ii) SnH'To~uTol.o(;y 1-" ( JvixEs.

The efteds of 7'. r·onqolcnse infedimt on sheep \Yere. wheu c:oucomitant c]i,eases were eliminai.eel, seldom a,; ::.iriking as on boYines. C'onsequentl_,. elassincati.on into perac-ute, acute and chronic

B. S. l'AitKIC'.

stales was not attempted. The apparf'ntly perat:ute cases, i.e. the cases which progressed rapidly to a fatal termination with thf' appearance of numerous trypanosome" in thf' hloo<l were, in most ca::;e:;, associated with a concomitant infection of hearh1·ater and tlw peracute state might Hot han' arisf'n if it \Yerf' not on :lt'Connt of the prf'SellCf' of t hi;; disease. 'l'he H.\' mptom:; i11 these casf's are tluts unreliable. Trypa11osomes, howevf'r, \\·ere 11umerou::;, an UJnu-mul finding i11 'I. r·on.IJolrnse inff'clion of ,;heep "·l1ell kept under f.aYourable conditio11s. The ('Ommon <·ou1·;;e the disea;;e in ::;hrep iakes is a primary acute form follmYe<l by a dnoni<~ form. X ot "·ilbsta tHling the frectuently l1igh tempe1·ature the life of tllf' shf'PJ> i 11 many t'ases

<loE's nol appear to he in danger. An examination of the sl1erp sho\\·s pale muoosae, U('('eleralecl pulse and respiration, sotne loss of <·o~tditioJt

\l'hi('h lofls, llO\\'f'Yer, is soon rf'<'OYered and an intprferen('e, 11ot marke<l, \\·ith appetite. The temperalHres sho\1· striking jl{'l'sistent Yariuiions "·ith periodic high and lo"· temperature,;. TlH' dil'kren('e in tPntper:dures tal;en al JO hou1·s· interYal.~ nta.1· l1e ns nn~<·h a,;

5-li⁰ 1•'. There i.-; an alhuminuri:1. The hlo<Hl e:xaminat ion l'l'Yf'ab

<1l:·HI as i11 t"attlP, an anaemia 11·hi('h i,; at a f:tirh lo11· le\'l'l parl1· in thr <li~rast'. Chart X

rr

illu~trates the 1'(:'(1 ('ell ji;P('ipitate or a siH'Pjl i11fe('Led witb '1'. r'OIIi)Olellse in <·otnp:trison '"it It that of onr infrl'(<'<l ,,·ith 1'. lwucei.

('ontnny lo what was detennined in ('altlP, the bloo<l in so1ue

~hepp ~ho\\·pd ani,-oC"ytosis. polycluoma,;in, ba,;ophilin and Jlormohla:it . .;.

Such changes <lid not o<·('ur in all the sheep tuHlPr ohsetTalion <111(1 may perhaps be in pan clue to a c·oncmTent Yenninosi;;. Xo endP<tYOlll' ,,·a;; made to as('prtaiJL the efl'eC'! of ndYerse enYironmenlal coJHlitiolt~

on infede<l sheep. The symptoms of '1'. run.!Julense infPction of ,;hPep are thus some\\'ltat meagTP, the striking fpature.; lwing- the trJltprr<llurP curve and the an<1emia as rldennined by blood examination. A,; :ut illustration of the persisten('e of thP marke<l ineg1tlaritit•,; of trmperatures ('hart Y is submitted, "·hi('h l'elJl'esPuts the tempe1·nture

<·m·,·e of the same sheep of the first four \\'eeks ancl tha.t of lhe l'2th four \\'eeks some ten months latPr. This is t'ontrarY to "·hat o<·r·urs in

<'attle for in thPse the tPmperature <'UrYP of c·ln;mi(' <·<\ses lwc·omPs ullimatph· normal under <·OtHlitiotts some\\·hat similar to those under

"·hi('h th~ sheep .arr kPpt.

l11 the pig,;. "·hi('h 11·ere infP!'!Pd "·ith tlJP lU10de,;ian and the Zuluh11l(l dog- strain, thf' pe1·i()(l of in('ubation <·oJTeciJlOll<l<'d fair!,,·

dosPh. The shOl'test pPrio<l "·hen judge<l from thP fir,;! appe>araJH·e of '{ r·oii.IJOiellse \\·as 11 <la\·ti atHl holll tlw first t-lendion nf tempentture <1bo 11 <lays. In. p,·er.'· <·ac;e, '"ith one exl'eption, thf' para,;ites \\·ere fmtn<l on the <lay of eleYatiou of tempPratnre. Bloo<l smears \Yf're ntili,;p<] for thi,; examination and tr5·1wuosomec; \\'el'P nb·ays diffil'ult to find neYer being c;o numerou,; that tiH',I' coul<l he rlPsnibe<l ac; heing fairly hPCLUPnt. 1n the examinations lmHle 011 LW clays, onl.1· 4 -~ \\'eJ·e foun<l to he po,;itiYe. Infl.uen('ing fa d on; mig·ht llaYP heen the good con<lition the ·pig-s \\'e1·e in at the <·onnnenl'emenl of tlte Pxperiment, an<l the gootl houc;ing and fee<ling. The iufedion ditl not intedf'Te "·ith gTo\\'th ancl no rhanges in nonnalit.\· of

25G

SY.\ll'TOAlA'I'OLOG Y OF SOC!JE TllYJ'.\1'10S01JL~SES ()],' ]JO~l ~STl<' A.KL\1,\LS.

defu.ecation, respnauon and appetite ,,·ere noted. Blood examinatwn for anaemia was uot carried out. The temperature curYes in all the five pigs eXlJeri.mente<l with sho1Yed the exacedn1tions and remicsiom;

commonly found iu 1'. eongole~tse i11fection of other animals, but the variations 11·ere not as mm·kecl, nA frequent, or as persistent aH, for example, in the sheep. The Yariations becamt:' less aecentuated Yer;~·

~oon after the passing of the fir:;t acutene,;:; of the disease. A temperahne curve eoYeriug the first four \\·eeks of the infection is represented on (;hart VI, together \Yith the bloo<l smear examinatiqn.

The 1'. congolense infection produced in the:;e pigs was of a subacute i.ype.. Other ohsen ers, especially in i.ht> Congo, have reported the disea:;e .as being peracute. Prohahly e11Yironmental conditions are the deciding far·tors.

(b) TRYPANOSOMA BRUCE! INFECTION OF EQUINES, OVINES AND CANINES.

J'. /;rlleei produces ~11 horse:; <lu acute diseac;e, 11·bereas in bo1·iuec;

an<l rn·ine:; i.he clise<I~e i:-; of a more l'lHOJlic ual11re, often 11·ilhou1 clefiui te d inieal sym ]Jtom s. T. h ^!'II ce i 1nls l he ead iest try pnnosom e llescribetl in dogs but there i:; the possibilit.\' that 1'. coii.IJO/ense pla,,·s a 111ore impmtant n}le in these animal,; than \l·a,.; rn·eyiously thong-Itt. 'Jiauy ollst>ners consir1er that T. !il'ucei is of t·omp<~nttlYely little importance for hm·ines- the:-;e animals merely acting as reservoirs tor the p::nasi ( es.

(i) 8DJl'T01L\'J'OLOGY lK EQUIKES.

The infection was pl'Orlueed in only one donkey. 'fhis animal

;;howerl a gradually progressing \Yasting disease without marked oscil- lations of temperature. 'rhe trypanosomes were easily found in st.aiued blood smears, oceasionally becomi11g frequent. The loss of condition an<l the 1\·eakne::;s of the animal \\-ere oln·iouR. The donkey ultimately died after a course of 20 ~~-eeks. In horses, however, the same shain whieh \\-as usell to infect the douke;~· produced· an aeute disease with a comparatiYely short cmnse-nt times less than or not much in exeess of one month. 'fhe period of i1l!:uhahon in the hmse may he as short ns 4 <lays, wl1ether ju<lgecl from eleYation of tempera- hue or .appearance of h·ypanosomes in stained blood smears. Gbnrl :;mears were difficult to make. In those examined no parasites \\-ere founrl. Anaemia, as determined by blood examinations, develop,;

and its dinical sig-nR are ;;oon evi<lent. \Yeakness ancl swaying gait;

inability to move at a fas(-t1·ot; rapid los,; of con<lition; pale lll11Cous membranes whir:h m·e ocC'asionally icteric; l'aprieious appetite; weak pulse whieh, when the animal is exercised, becomes marke11ly ac<:elerated; impaC'tion of the. heart against the l;hest \Ynll rletenniu- able by palpation and by sight; hide bound condition of the ;;kin, all appear early in t.he disease. An observer is particularly strul'k hY the los;; of eon<lition anrl the \Yeakness. Anaemia cau he definitelY d~moHstraterl bY the bloorl examinations. The number of reel eells

<lecrease as doe~ the pe1-centage of reel cell preeipitate. Chart VIII represents the changes i11 the re1l l'ell precipitate of horse 20417. 'fhe infection in this ho1·se is not as acute as in some other case, and furhermore, there is wme sli.g-ht intederenr·e towards the end with

256

H. S. PARKIX.

the anaemia by the introduction of a treatment which resulted in the disappearance for short periods of the trypanosomes. The effect of the latter is probably a decrease in the rate of decline of the precipi- tate. Notwithstanding it ran be seen that the anaemia progresses fairly rapidly. Oedema and eye-lesions do not .apvear in every case.

Photograph 5 illustrates the oedema in one case while photograph 6 illustrates the appearance of a case of T. bnwei infection of a horse in which oedema and eye-lesions did not .appear. This photograph waH taken on the clay of death. The horse of photograph 5 showed slight opacities of the cornea. The temperature curve of 1'. lnucei infection ·of the horse is Yery striking and of all the trypanoFomiases worked with this disease gi.Yes ]H"obably the most characteristic curve. Chart IX is submitted as an illustration. Of interest in this disease, on account of statements aheafly referred to, iR the progreRs, at times, of the disease in the horse to a fatal issue without the development of oedema or the appeara nee of eye-lesions. The trypanosomes are often difficult to find in blood smears but occasionally they become extremely numerous. By appropriate manipulation with drugs the parasites can be controlled to sueh an extent that the horse may liYe for years without further t-reatment. In such cases the parasite it>

extremelv clifficult to detect in blood smears .aucl subinoculation of a small qn.antity of blood into a susce11tible horse may fail to transmit the !lisease. Yet the state of the horse is not entirely comparable to that of a bm·i.ne premune to 1'. congolense for the horse does not arprrJach .as near to normality .as does the bovine. The horses used were old ones, whereas the bovineR "·ere young. Possibly better results "·ould have been obta ¹ n eel if young horses had been us eel..

(ii) SYMPTOMATOLOGY lN CANINES.

Only a few dogs were placed under observation. In every ease the infection was producec1 by the subeutaneons injection of blood of a horse infected with 1'. bnteei. The shortest periocl of incubation in these clogs was, when judgerl from the first appearance of the parasite in blood ;;mears, seven days and from first elevation of tem- perature sixteen days. If further subinoculatiou had been carried out possibly shorter periods would have been ohtaine!l, for the strain of T. brucei had been maintained in horses for h.-o-aur1-a-hal£ vears.

The trypanosomes were in most eases difficult to find in the "blood smears. The eourse eomp.ared with 1'. congolense infection in the same animal was long and even though death resulted ultimately i.u all the cases there was not the same acuteness associated with the infection as with that of 1'. congolense. 'rhere were no symptoms of note other than the fever symptoms. The absenee of oedema and of eye-lesion 8 as eom pared with the definite development of these in T. congolense infection is of interest. (See Chart X.)

(iii) SnrPTOMATOT.OGY IN SnEEl'.

Of all the trypanosomiases obHerved 1'. ln'1tcei infection of sheep gave the most meagre symptoms. Other than milcl fever symptoms,

~Yl\U'TOMATOLOGY OF S<))-IE TH YP.\NOSO~JIA~ES OF JJO}LESTIC ANIJ\IALS.

no abnormality was determined. The temperatures at the eonuuem:e- ment of the infection are somewhat irregular but they soon settle clown to a comparatively non-oscillating type (see Chart XI). The parasites "·ere extremely clifficult to find in the blood smears.

As an illustration of the diffieulty of diagnosing the infedion by this means may be instanee<l the blood smear examination of three sheep, the first, seeoncl an<l thinl generation of the tryJmno~ome afte1·

leaving the reservoir, a horse. In the first generation one trypano- some was found in 22 hlo0cl smear examinations, an<l in the seeon<1 and third no trYlJanooiomes were found in GO examinations. 1'hr eomplement fixation test \nts positive. In adrlition gla11cl ,.nnears \Yei·e exmninecl ''"ith JJegatiYe results. There are no inclicatiou~ of anaemia ''"hen judged hom the detennirwtion of red cell pnwipitate. Chart XII gives the <leber·miuations in a shee1J infectec1 "·ith T. hrucei and in one infeder1 \Yith T. con.r;ofrusr. ln another sheep the red cell precipitate sbmYed practically no Yariation during the perioc1 of obser- vation '>Yhi('h extenderl from the 24th June to 2Gth Augu..;t, 1932.

(c) SYMPTOMATOLOGY OF T. vivax INFECTION.

SYi\IPTO~IATOLOGY IN Bovr~Es.

This infection "as produced in all cases except one by the injection of the blood of .an infected bovine. As these carriers of the infection had at ::;ome previous time been infected with PitozJlasma bigen1-1:mnn ancl, or, Anapla.-;IIW IIWI'.(}inalc the 1'. ~·iuax infeetion "·as complicated with these diseases. Consequently the temperature cm·ye did not gi Ye a true index of the T. t·i au; infeetion. In the exception noted aboYe the T. viva .. -v '>Yas transmitted to a bovine bv the bite of a tsetse fly. This temperature curve on Chart Yil is othus the only true curve of T. rirr1.r infediou aYailable. The temperatures subse- quent to the initial stage do not show marked exacerb.atious and remissions. Constih1tional disturbance;; are not conspicuous. There is at first some inappetence ancl a lo,.;s of eon clition, the latter of \Yhich might not be fully rE>coveretl for a fe,, months. During this period of ba<l eondition the coat is dry and poor in appearance. The superfiC'ial lymphatic glands are enlarged. The parasites are difficult to find in the blood smears. In one ease, bovine 2727, the animal wa:; not treated and regular examination of both blood ancl gland smears waH carried out over a period of 44 weeks. During the ;33rc1 \Yeek T. m:va.r was found in .a gland smear, but no tr:vpanosomes were found either in bloor1 and gland smears for 1

o

^'>'~eeks before anr1 11 weeks after this finding, representing in all an examination of 108 smears.

T. viva.7' infeetion in bovin~s unr1er the eom1itions ]Jrevailing at Onclerst.epoort thus is a disease whieh does not produce effeets of any great severity. The majority of animals recover, i.e. they regain their normal condition and appearance without the institution of treatment. The possibility of a spontaneous sterilisation must also be r:ousiderecl. (For further information on this matter, see the report by the writer whieh is shortly to be publishecl in the Onderstepoort J OUI'IICll).

ll. S. 1'.~\BKI::\.

LITl<;HATUHE.

CUHSON, H. H. (1928) ).'agana in Zululand. l:3th <Uid l4t/, He1Ji5. of the JJir. ret. Educ ^Ull·cl He-'., u. of S.A., pp. :309-4Ul.

HOR:\HY, C. (1\129). Annual Hept., Dept. of Vety. Scn~ic<'s. T:1nganyik:l. :PAI1~l{l~, H. S., .-\1\"D ~HOHI\BY, C. (19!30). A contribution to the study of

"Immunity " in Bovine Trypanm,omiasis. 16th He1d. JJir. T"ety. Sac. cC:

.clnim. l11dust., Union of S. Africa.

J (u).

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