Report on 3-year follow-up of ocular onchocerciasis in an area of vector control

? h)? WORLD HEALTH ORGANIZATION ORGANISAT]ON MONDIALE DE LA SarurE Onchoceroiasis Conf,rol Programne in the Volta Basin Axea RPoRT 0N A J-YEAR rOLLolI-Up 0F oCUr,An oNCHoCIA.CIASIS I}T Ai[ ANEA OF trT:ECTOR CO}NIROL Elid.omiological Etraluation Un:i t Technioal Doc. OCP/EL/7 a.4z By B. Ihqrlefors & A.l'1. ' -\,:'.T/njum" " I a Ophthalnologist, i,rIHO Onchocerciasis Control Programlie in the Volta River 3asj.n Area, BP 549t &ra6ad.ougou, Upper Volta. -)ia+ Q6ngultant Ophtaha'lmologist \IH0, associat€ professor in ophthal- moIory, Un-i.versity of 0s1o, Norcay. Ii.IIBODIICTlOII The lrrpact of ocula onohoce:rclasls ln temrs of severe eye leelons and. blindness is lnfluenced. by tJ:e lntensity of infeotj.on and f,rqns- nisslon of the d.isease. fhe d.evelopment of omohocencal eye l-esi.ons in arsa€ of ongolrlg trznsnlssi.on has been stud.led ln !/est Afrir" ((,,ZA) Uut very Umlted d.ata a,ne available frour areas where the vectore the @}!ggf1yr has been elinirated (, or r:nd.er control meacrures (5). ffr" cou.rse of oncho- ceroiasis may ohange sigrdficantly when a control of the vector ls estabIlshed.. An lnterzrrptetl or heavlly reduced. transmlssion of Onchocerca rrcImrlus rri1I bneak off tJee accumr.rlatlon of parasS.tes ln the hnman body a.::d. thus inltlate a sta6e of s1ow1y d.ecreasi-ng intensity of fuifection. [Lre influence of thls on existing eye leslons and. the risk of blind.ness j.s not b:own, but is of LrmTed.iate lnterest for estlmates conoerrdng ure pred.:Lctable a,nourt of blindnese due to onchocs:sciasi.s. TLre Onchocerciasle Control Prograrnne ln the Volta R:i.rrer Sasln Area is baseal on vector eontrol, which was lnitlated ln \975. A tletailed. ophthal- mologlcal evaluation of patients living in selected villtlges in the progra.Erae erea, was oar=led out 1n 1975 and €€ain 1n 1978, i.e after a l-year period. durlng which there was an almost complete internrption of transntssion of Oarchooe:roa volvr:-Lus. accord.lng to avaj.lable entomological results, the J-trear foIIow+rp of tJ:e d.evelopment of ocular onohocerciasj.s in such an a,rea of vectcrr oontrol 1s presented. in th5.s report. I 2]'IATIITIALS AJTD i\E'IiiODS A total of 5 vi]la€ps situated within the Onchocerciasls Control hogramne area ln the Volta River Basin were e)€&inecl ophthafunological)-y in 1975 arrd ]-g|Bt corxesponding to a 1-yeat period. of vector control. Tkre rnillages i.ncluded in the study weret Houvi6lo (fo"46t't, l'ogll) at the Upper Bougor:riba river in Upper Volta. - Icnpdo (t0.41N, 1"12\l) also at the Upper Bougouriba river. - Pentltd (tt.O4S, 4,41\,1) at a tributa.ry to the Flack Volta in Upper Volta. - GeneBn}pe (fo'491t, 2o5o\I) at the Black Volta in Gharra. - llidnaba (t0"57u, O"l4l'I) at the Red Volta in Ghana. Tire vector control in the area ooncerned was measured. by means of regular catches of Sl-mulirrn d.amnozum at catching polnts sifi:ated. close to the uillages el@ririned. in this str:dy. 'Ihe results, presented as Annual fhans- c'Lission Potentlals, showed. for the concer:red catchj.ng points during the obserevation period. ATPS ::anging from O to 1BB infective t^oru.e/^ary'yea*t'. In this report these values are consid.ered. as indi-cators of a relel'ant vector control, antl the oomplex interpretation of avaj.lable entomologlca-l data is not further d-i-gcussed.. A 1oca1 census was careful.ly prepared. ln each village to ensure a representative proportioir of tlre population being' examj-ned.. ..,1, -x-^from the Vector Control Tlnitr Onchocerciasis Control Progran'rme in the Volta ltiver &asin -\rea. 1The visual acuiff was tested. for each eye sepa.:cately without glass correc- tlon, using an i11ite ato t'Iltr or i{and.-test at ! meters. The ophthafunological e:camlnation took place ln a dark room, with a slitlamp (Uaa6-Streit !OO, nra,gnifi-cation x15 and x25) and ophthalmoscopy. lhfore the examination of the anterior segnrent of the eye, each patient had his head. bent down for a mialmum of 1 minute. The number of living microfilarlae in the anterior cha,mber vas then cor.mted., always startlng with the right eye. Dead. and. li- vit"lg microfj.lariae in the cornea and onchocornea.l opacj.ties were also cor:nted.. fhe pupils were then d.ilated with troplcamide 196 eye drops, if no oontra- lnd-ic-ationr and. direct or ind.irect ophthalmoscopy of the fundus was carrled out when possible. Tn 1975 one obse:srer oarried out aLL the ophthalmolog"ical exae,ri.- natlons whereas during 1978 at the fo11ow-up tvro more obse:srers were involved. in the evaluation. 4n-ES-IILIS The population exa.mined in each village in 1975 and 1978 is shown in'Iable 1. The re-attendance rate, i-.e. patients elra,fidned. on both occasions, ranged from 471J to l6r6l.i when calcu.l-ated on the basis of the 1975 sanple. Ilowever, no correction for population movements or d.eaths has been mad.e. The overall prevalence of ocular onchocerciasis, d.efined. as the prerenco Of rniorofilariae kn the anterior seguent of the eyer has not changed, significantly over the J-year period. even if there is a tend.ency for lower prevalences per vi11a6e in 1978. Hovrever, the age-specific pre- valence for the a€e-groups below 1l years showed, a decrease because of non- lnfected ind.ividuals being grad.ually includ.ed. in the saarple after i years of vector control. Table 2 shows the &istribution by age and sex of the patients that were examl-ned ophthalmologically both in 1975 and,1976. The composition of the exa^rnined. population resembles closely a lcaor^rn stand.ard. population frorn the area concernecl. A1so, the prevalence and d.istribution of severe oeular onchocercal lesions in the non-attending and. attend-ing populations were sim-lIar, thus ind.icating that there was no irnportant bias in the exa- nined. population concerning intensif,y aird. gravity of infection. Table J shows the incid.ence and. d.isappearance of siSns of ocu-Lar onchocerciasis in the anterior segnent of the eye. The incid.enco of visible microfj-lariae ana/or cozrreal opacities shows a slight decreaso by age above the 15-29 year group, siuilar in both sexes. Ilowever, these ocular signs d.isappeared evenly in all ag:e groups and with a slight female pred'ontinartce' ...r, 5fn Table 4 the quantity of microfilariae and. onchocorrreal opacities in the anterior segment of the eye is shown. fr:e number of livi-ng microfilariae in the anterior ciramber of the eye showg no siSnifj.cant cha.nge betrveen the exaninati-ons in l/lJ and. 1!JBr whereas the quantity of both clead. a1d. living microfilariae and their opacities ln the oornea has d.ecreased' sigrrifica4tly over the ,-year period.. An analysis of obsel:ver variation d.emonstrated. a clear d-ifference befi"een tlro observers concerning the nr:-mber of microfiLarlce in the anterior charnber, but no such inter'.obsertrer variation wae found. concerning the co.rtea,I signs. The incid.ence of severe ocu-lar onohocercal lesions and. blindness is shown in Table 5. The j.ncid.ence of choroid.oretinal lesions d.omj-nates oompared. to otl:er lesi-ons, arrd onchocercal blind:ress shows a rernarkably low i-ncid.ence which is confined. to l.,he 30-49 years a8€ group. Table 6 shows the &istribution of irreversible eye lesions in the population examined, and. their tend.ency to d.eteriorate. ftrere is a male d.onrinarrce for severe ocuLar 1esi.ons, especially for those deterioratin8. Choroid.oretinal lesions seem to be nore prone to d.eteriorate compared. to the others. 6DIf]CUSSIO}T The tota-I attend.ance rate in 1978 was 611 51', as cornpared. to the 1975 sample. fhe re-.attendanoe of patients naried- considerably in the dif- ferent vilIages, but no systenatic investigations concetnlng the reasong for non-attend,asce was irnd.ertaken. However, j-t seened. that seasonal niSration 1n certain villages was an important factor in tkr-is context. Alsor the re- attend-ance rates ar:e seemingly low as population novenents and. d.eaths were not corrected for. Attend.ing arrd. non-attenrJ.ing populations were compared. concerni-ng their distribution by a6e and sex as well as prevalence of severe eye lesions' jrlo blas regard-ing the re-attend;ll6:sanple was forrnd. using these paraaieters, a1d. lt is therefore assumed. to be representative of the populaf,ion ooncerned.. The overal.l prevalence of oeular onchocerciasis varied in tl:e 5 vi[ages j.nclud.ed. in this str:dy. [kre pre'valense rates, were slightly but consistently lower in I!JB, with an average di.fference of 2r6iJ. The decrease is mai.nly due to a considerably lower age-specific prevalence of ocular onchocerciasis in the ag€-g?oups below 1) years, because of more non-infected. cldldren ln the sa^rnp1e as a result of the vector control' ftre j.ncid.ence of ocuJ.ar onchocerciasis in the population e:caninod. l-975 and.1!lB shows a slight decrease by age after the 15-29 yaers aEe g?oupt and tlds was sirnllar in both sexcg. The intensity of infection is of impor- tance in this context, as the presence of microfilarlae in the eyes usually signify a certain leveI of parasite load.. ['huse e1d.er1y patients ]rave a higher 1eve1 of probabiliff to already have established. a suffj.ciently in- tense infection. a a ar'' 7An intermpted. or significantly reduced f,ransnlssion will in this context tend. to d.elay the appearance of ocular signs of orrchocerciasig or confino it to. incLivicluals tjrat were infected. before the begir:ring of the vector carapaign. llee totaJ- incid.ence cf ocular onchocerciasis in this study of OrBi., can be cornpared. to the high incidence 6t l.},j for onchocorneal i.:Gcities aloner that,lnd-erson et a1. (1) forrnd. Ln a tl-year foIlow-up of onchocerciasis in an aroa of ongoing f,ransnj-ssion. Ttre d.isaptleararr.ce of visible microfilariae or corrreal opacities from the anterior segnent was forurd. in all a€ie-gEoups and with a slight female d.ominance. /rgaine the intensity of infection is of irnportance and the vector control may possibly have given a stable or i.n certain cases d.ecreasing l-ev;l of rinfection. Observer variation may be of importance concerrring the &iagrosis of early or light ocular involvement in onchocer- ciasis. Iloweverr no sigr-r-ificant obse:rrer variatj.on was found. concerning corrreaf sigrrs in ti:-is study. itrrthermore, the recluced. quantity of microfi- lariae j-n the corrrea found. Ln l97e supports our find.ing of an tranti-incidencert of ocu-Lar signs. 1'he i-ncid.ence of i:reversible eye lesioi:s cornnonly for:rrd. in onchocerciasis, i.e. scLerosing keratitis; antericr uveitis u-ith s;'nechiae, choroid.oretinltis aird post-neuri-ti.c o1:tj-c af,rophy, shovrs a cornplex 1:atterrr. Sclerosi-ng keratitis was fou:rd in only one patient, whereas choroid-oretinitis showed. a relatively high j-ncid.ence aird. olti-c atrophy again was rare.'-lhese findings are not j.n accord.ance with the results of t'u:d.erson et a.1. (f) wiro found- a similar incid.ence of sclerosing keratitis and choroid.oretinitis of 4r5l: resirectively 4t2l!, over s, rf-year period.. One possible erplanation for the find.ing in tire nresent stu{y is that the reduced. trcrnsmj-ssion of breaks off the build-up of onchocercal infection and ocular0. volu.:-1us a a.t' Beurd. ocrrlar lesions that are a.ssoclated. wlth high microfjlarial loads are then less llkely to appear. Sclerosing keratitis usually represents a4 llterrse ir:fection with kr-igh numbers of nicrofilarlae present j-n the ari- terj-or segrrent of the eye, whereas posterior segtrent lesions are much less corzelated to the rnicrofllaria1- loa.d. (i). Cnoroidoretina.l lesions r,ray there- fore ensue and d.eteriorate even j-n less intense irdectionse ai:d. the Lnpor- tanoe of rolrorofilariae in the anterior cha,rnber as a risk sign ln this context has been pointed out Qr!r{). T fr" nuriber of 1ivi4g r.ricrofilari.ae in the arrtsrior charnber of the eye d.icl not change over the 1-yeat period. in this str:.d.y, 3ut a lr-iglr-1y signj.ficant decrease cf the prevalence of such microfi- lariae has been reported- after a:r B-year period of vector control (!). Ttre slg31ificantly d.ecreased quar:tity of corneal mi-crofilariae found. in 1]J.9 1n the present study inay well be j.n accordance w:ith the verry low incidence of sclerosiitg keratitis and. the relativo stabiliff of that lesion at the fo1low-up. The d.:isf,ribution pattezn of i-rreversible ocufar lesions in the po- pulation exarnined. in L975 and 197S ehows an increase by agB ancl a nale d.omi- nance, whicir in accord.ance rqith previous suJrreys. I'Iowever, the rate of d.ete- riorated. lesions is consid.erably higher in males, wh-ich may be due to their usually nore lntense infectj.on. Tlee overall rate of d-eteriorated- lesj-ons seems to be 3-ow1 but &irect comparisons with other studj-es are coinplex as these lesj-ons at a certaln stage tend. to be self-perpetr:.ating regard.less of the intensity of infection. Ilowever, it should be noted. that iu:d.erson et aI (f ) in their 4-yedr fo11ow-up found. that sclerosing: keratitis rnras mcst psone to d.eteriorate, whereas in the present study choroicloretinitis d.eteriorated. to a hlgher extent thar: the other lesionso Again, the d,ecreasing microfi- Iarlal load. in the cornea found. in thris study is j.n accord.ance with a ten- tend.cy for sclerosing ke:ratitis to remaj-n stable . .,./l 9Ttre incid.ence of blindness due to onchocerciasis was linited. to one a€e-gpoup in our sarnpler md there was a male d.omina.nce. The overall rate seems to be 1ow, but the figures a,re too sma11 to allow a reliable sta- tistical- analysis. ilowever, it shoul-d be noted that all t]:e for:r patients going b1ind, ir; the present studJ shovred. irreversible and. severe eye lesions in 1915, which is }ceow-n to signify an i-ruportant risk of blindness anyhow Q-,!), The m:mber of microfilariae in the anterior segnent of the eire has been shown to related to the risk od deteriorating eye leslons and blind.ness Cr2) and it may also be a useful i-nd.ioator of the intensity of infection in terros of severe rcu).er lesions G). nl" analysis of the quantity of nicrofilariae in the anterior segnent cf, the eye in the present sturd.y showed. no significant change concerning the nu.nnber of nicrofilariae in the charnber, but significantly reduced. numbers of mj-crofilariae arrd. onchocorneal opacities in the cornea. fleis may ind.icate that the aqueous humour is a more favourable ned.ium f or the survival of roicrofilariae tha:r the corneal stroma. Obseruer variation is an important factor to take into conside- ration in a folIow-up sujrvey. In the present stu(y the sane ophthalmologist carrj.ed, out all the erai:rination in 1975, but two more obse:srers participated. in the 1978 follow-up. It is therefore of utmost importance to obtain an estimate of the correlation between the J obse:sreps.'lhere was a good. inte.:- observer agreement concerning the mlmbers of living and dead. microfilariae in the cornea as well as onchocorneal opaciti-es. I'Iowever, regard.ing the numb:r of living mierofilariae in the anteri.or chainber of the eyel there were d.iffe- rences at the p- 0roo1 leve1 of signifi-cance between two obse:srers. but the vari.ance of the mean values of each observer was lirlited-, thus ind.icati-ng that the number of microfilariae i-n tlee anterior chamber was in fact unchart- ged.. aa 10 '&re cornea.l. find.ings are on-1y related. to variance of id-entification artd. counting techn-ique, where'as the assessment of the quantity of nicro- filariae in the anterior rhar,rbc-r is less accr:.rate because of thelr mobility and. tend.ency to sottle in the cha,mber angle. iiowever, i.t must be und.erlined. that al1 three observerg had consid.erably more experience in the speclal eramination technique for ur-lcrofilariae in the enterior segrnent dr,rring the foI1ow-up survey in 1978 which rather urrderU-nes the significance of the d.ecreased. quantity of raicrofilaria.e in the cornsa found. in 1!/8. It CCITCLUSIO}TS A fo11ow-up dr:ring lll8 of ooular onchocerciasis in 5 vl11ages sltuated. within the Onchocerciasis Control prograrune area has d.emons_ f,rated. the following effects of a J-J'ear period. of vector conholr - the overall prevalencg of ocrrlar onchocerciasj.s has not charrged. strikingly, although the rates are consj.stently lower in I!JB, especially for the a€p-groups below 1! years. - the total -415!1ry of ocular onchocerciasis in patients e:ra- nined. both in )-975 ond- 1!/B lras Br6t'). Ilowever, there was also a di.sappearance of nj.crofj.lariae from the eyes in a total of 11r59j of the indlviclual-s. Tl:e incid.ence of ocuLar signs of the d.isease may be due to infections esta- blished. bcfore the beginning of the vector carcpaign, and the nantj.-incid.encen due to d.ecreasing light infecti.ons as a result of arr intern-r.pted. f,ransruission. .. tho incidence of severe onchocercal eye lesions was consid.erably lower than has been fou::d. i-n areas of ongoing trarrsmi ssion. lJsol the pattern of new severe o1'e lesi-ons was d.i-fferent with a particularly 1ow j-lcid.ence of sclerosing keratitis as compared. to choroid.oretinar lesions. - the tendeney for eristi.ng severe eye lesions to deteriorate was 1ow, especially i.n femaf es. - the overall incid.ence of blindness due to onchooerciasis was OrJi.. A11 patients going blind. had severe eye nanifestations already in 1975, wL:-ich are ar5'how associ-ated. r,rith a higir risk of blindness at ar: early stage of vec- tor control. - the d-ecreased- intensity of ocu]ar involvement due to onohocerciasj.s was readjly seen in a signicantly red.uced. ro-iorofilarial 1oad. in the cornea. ifl:e mrmber of living nicrofilarlae in the anterior chamber was apparently rrnchang:ed. and it was d.emonstrated. that observer variation must be taken into consid.erati.on in this context. ...,/ 12 .rrCIGIOl/LrlnG]IIX{T llo acla:crwledge the valuable participatlons in field. ovaluations by Dr A. R.o11and. and tho statistica-l adrrice given by Mr T.F. d.e C. I'Iarsha]I. 1 o t1 t',rtrE1ltrUcES And.erson, J. IIT AL. Stud.ies on onchocerciasis in the United. Cameroon Republic. flf . .[t. four-year fol1ow-up of 5 rain-forest and 6 Sudan- savanna vi11a6es, 'ftans. rolr Soc. f,rop. i'-red. Ilyg.r 1% 162-171 (1976). 2, Bud.d.en, F.II. The nat:ral hj-story of ocufar onchocerciasis over a period. of 1,!-11 years and. the effect on this of a single course of suramj-n the- raly. Transo ro/. Soc. trop. iied. I{yg.2 l9-, 454-491, (tgle). 1, iioberts, J.ri.I. L"Ir LL. Onchocerciasis-in i(enya g, ll and. 18 yeaxs after cliralnation of the vector. b\ll. I,fLd. l1eaftf, Org, if_, 195-212 (tgel). 4. Ro1land., r\. ,i"f AL. lholution sur 9 ans d.e lronchocercose oculaire une cof,nnunaut6 villageoise drAfrique Occid.entale. 8u11. \.fld.. ilealthj5, (5), eo5-e1o (19Ts). d.ans org 5 Thyleforsl .t3. ,1, Ro1land., :1. Situation d.ans ul foyer dronchocercose duliali aprbs treize ans c1e contr6le anti-sirmrlid.ien. 2. Aspects oculaires Arrn. soc. belge lbd. trop. , DJ, 6, 577-jaz (t977), 6. Th1rls1a=r, B. .i; llrinlcrnarr:e, U.K. The microfilarial load j-n the anterior segment of the eye. l^' paraneter of intensity of onchocerci.asls, ru1l. t,Il-d. Health org. 12, T1t-7i7 O)TT), t4 Table 1 The population exa.rnined artd. prevalence of ocular onchocerciasis in 1975 and. 1973 per vilIage. The re-attendance rate is calculated on the IlJl saTnFle without correction for cleaths or nr-igration. -x-) Rates afiusted. for age and. sex. j.975 Re-attend.arrc. (i'6) tzt 0e ,e:\) 54 0l rq!') t36 (5i r5;:) 109 (+Z rq,j) t26 (ll,l;:,') 5,tr6 (51,6iJ) t978 Village ilxa- Coular rained. oncho- cerciasis Eka- inined. 0cu1ar oncho- cerciasis Iviouvielo ]-56 6417i iClmp6o 74 4tr45 I'end.i6 25,1 lO rT3 Gengenlcp6 212 4i ry' i/idnaba Ul |9rSrJ Total = BS7 47 r7t3 151 6orn3 6g iSrq's 1S7 2811c7; t42 17 rT; lsg 55 16;(, 718 45 rt); '1 tr -L) Table 2 Tne d.istribution by ato arrd. sex of the sample exa^urlned both in 1975 and 197J. j''lales Femal-es AgE Ixamined. (r0 Ilxamined. (:;1 544 154g io49 L 50' Total 6g T1 E1 55 (z4ra',3) (z6,li) (z9rt;,) (r9, oi5) 67 75 OD 31, Ib Table J Incid.ence a.nd. d.j-sappeara;nce of irisible microfilariae m4rbr onchoqpnaal opacities in the a,nterior segIrent of the eye. Age Incidence Ita.les Fomal-es /mti-inciderrce j,ia-1es f,'ernales 5 -t4 t5-29 50-49 + 50 TotaJ-r 6 (B,7ii) 10 (1r,7i6) 6 (7 r4',3) 5 $,5i3) 25 (9,q:) s 0,s:3) e (rc, 79J) T 0 r5')'") z (>,Y!) 22 (Br}i'o) B (11,6i'j) 9 (l:zr5"'o) + $,q5) 9 (14?6i:) 29 (tor4i'") > 0,s:';) 12 (10r0;i) t2 (D rU);) s Q+,t:!,) i+ (tzrr:!) 47 (8,6)!,) D17 t'.\ o N\S@r{ aaa r{ r{ Lt.r r-{rtt \o D'- fn@ \O ...\ aaaO t'.\ r-'|vv\/ N @ a Lr\ @ o r{ o r{ N r{ a r{ N N o\o \o I +'lts "?lE,a t--1 tl t/ '1 '-i c4 ts :.1 l-1 E H Er(J 3 ;-aT-li:ii Ic F-r .J t1 'ts,1 E{ H a Fl O rlOO l-r-l C) rl H aa :-1 HtstO Fi l-l tt-- rl tsH f N ctr N @ r-l O N Rl8 o\ tr- r-{ OOO .-i EtsP::EE5 O'\ r.r\ CD ^ls ix s*i at"t aI f,lT'l r\ I.{ l:-1 ()oia Frtir) (n .-:l CDf.-o\ -{LTF E4 l:pq El D 1B I Table q The incid.erroe of irreversible ocular lesions and. blindness by a6e and- sex. -:i d.cfined. as visual acuity less than t/ZO aetter el,'e witirout co:=ection. 1(1,5 - r (r,+) - lG,l) r(r,r) l(1,1ii) r(0,49i) orn( z(r,rii) - or 6tj rlge Solerosingj iceratitis M (?,1) F Choroido- retini-tis r,1 (t j) F 0ptic atrophy 11 (tj) r Blind.ness l'i (tJ) F t5-29 10-49 50+ Total: r(r rz ) 1(0,49J)- o '2i3 1(1,5) z(z,l) +(>,s) 6(7 ,5) 's(B;) z( lrr) B(4,ti3) 1c(5,T,) 5 r}ij 'to Table 5 The d-istribution by age ancl sex cf irreversible ocular lesions and their tendency to d-eteriorate. ;: rLefined as sclerosing keratitis (Slf) anarior iritis with sy:rec[iae (fn) anaT'or choroid-oretinitis (Cn) a,nclr'or post-neuritic optic atrophy (ol,). I Unchanged. - irreversibleocular JesLOnS 3u1"31eratod. ocular lesions I'lales iremales iiales iremaleg 6-] 6 t5-'29 1o-49 ri(l' 'Iotala 0 o 1CrL// 1C 15 0 5 15 6 26 0 1 Cir ) vlr 1 SI, 7 0 0 1 Cl1 I 0