Intro duc tion

Due to the con ti nu ous urba ni za tion and con trac -tion of the area not trans for med by hu man ac ti vi ty,ma ny ani mal spe cies ada pted to the sy nan tro picenvi ron ment. Among them the re are all com po nentsof zoo no tic fo ci struc tu re. The ro dents, be ing the re -se rvo ir of ma ny hu man and do me stic ani mals pa tho -gens. The ir vec tors – blo od suc king ec to pa ra si tes –be co me al so the com po nents of sy nan tro pic fau na[1]. In the urban are as, the most com mon ro dents arerats – Rat tus no rve gi cus, Rat tus rat tus and mo use(Mus mu scu lus) [2]. Mu ni ci pal re cre atio nal are ascan al so be in ha bi ted by ro dents ty pi cal for wo -odland are as, such as the bank vo le, Cle th rio no mysgla re olus, Mi cro tus vo les and Apo de mus mi ce [3].

The abi li ty of rats to acqu ire and spre ad of vi ral,bac te rial and pa ra si tic di se ases of hu man and petshas be en com mon ly known and well do cu men ted[2]. Ho we ver, the re are on ly few da ta ava ila ble abo -ut pa ra si tes of no me di cal im por tan ce, as blo od pa -ra si tes, in fec ting sy nan tro pic ro dents. They are fre -qu en tly en co un te red, but the know led ge on the ir ef -fect on the host’s he alth and on the ir in te rac tionswith other pa ra si tes is we ak.

Try pa no so ma (Her pe to so ma) le wi si (Kent,1880) La ve ran and Me snil, 1901 is a pa ra si te of Rat -tus rat tus and Rat tus no rve gi cus. The ear liest de -scrip tion of this try pa no so me, from Rat tus rat tus,da tes from Fran ce, 1850. It was la ter re por ted in Au -stria, for mer Cze cho slo va kia, En gland, Rus sia andthe USA [4,5]. In Po land, the ir oc cur ren ce in theblo od of wild rats has be en do cu men ted for the firstti me in War sza wa by Kar bo wiak and Wi ta [6]. It isa co smo po li tan spe cies. The rats are com mon ly in -fec ted, ho we ver, the in ci den ce of in fec tions va riesin dif fe rent parts of the world, de pen ding on the dif -fe rent eco lo gi cal and zoo ge ogra phi cal con di tions.Ho we ver, the ana ly sis of va rio us re ports shows thatin the po pu la tions in ha bi ting this sa me lo ca li ty, thein ci den ce of T. le wi si in R. no rve gi cus is usu al ly hi -gher than that in R. rat tus. The pre va len ce of R. nor -ve gius in fec tions ran ge, de pen ding on the se asonand lo ca li ty, from 2.3 to 41%. The pre va len ce va lu -es R. rat tus, ho we ver, are be twe en 7% and 29%(Ta ble 1). The in fec tions of other Rat tus spe cies areknown as well. Kart man [7] de scri bed the in fec tionin Rat tus ha wa iien sis. Other mam mals we re re por -ted as ho sts [5], among them hu man [8], but themost re cent so ur ces re ject the lat ter option [9].

The occurrence and ultrastructure of Trypanosoma(Herpetosoma) lewisi (Kent, 1880) Laveran and Mesnil, 1901,the parasite of rats (Rattus norvegicus) in Poland

Grzegorz Karbowiak, Irena Wita, Urszula Czaplińska

W. Stefański Institute of Parasitology, Polish Academy of Sciences, Twarda 51/55, 00-818 Warsaw, Poland

Corresponding author: Grzegorz Karbowiak; E-mail: grzgrz@twarda.pan.pl

ABSTRACT. This study reports the light and electron microscopic examination of Trypanosoma (Herpetosoma) lewisi(Kent, 1880) Laveran and Mesnil, 1901, isolated from rats (Rattus norvegicus) from Poland. Bloodstreamtrypomastigotes were identified morphometrically from 100 specimens collected from three naturally infected ratsRattus norvegicus. Body length ranged from 15.45–23.64 µm and width from 1.3–2.32 µm while the free flagellum was8.1 µm long. Electron microscopic study of bloodstream trypomastigotes exhibited typical ultrastructural featuressimilar to those of other stercorarian trypanosomes. The presently determined morphological data have been comparedwith those provided by other authors.

Key words: Trypanosoma (Herpetosoma) lewisi, Rattus norvegicus, Rodentia, Poland

Wiadomoœci Parazytologiczne 2009, 55(3), 249–258 Copyright© 2009 Polskie Towarzystwo Parazytologiczne

The in fec tion is ob se rved in young in di vi du alsma in ly, to 4 mon ths of age [7,9]. This fact is cau sed,pro ba bly, by the po ssi bi li ty of in fec tion of youngani mals by fle as as ear ly as in the nest, and on theother hand, by the fact that rats acqu ire the re si stan -ce on the next try pa no so me in fec tion [10]. Mo re -over, the ma les are mo re com mon ly in fec ted thanfe ma les. It can be al so ju sti fied by be ha vio ral fac -tors. Ma les pe ne tra te wi der are as than fe ma les andthey are mo re ac ti ve. The re fo re ma les are mo re li ke -ly to pick up fle as and con se qu en tly try pa no so mein fec tion [10,11].

In tem pe ra tu re cli ma te zo ne T. le wi si is trans mit -ted by rat flea, No sop syl lus fa scia tus, whi le in tro -pi cal co un tries by orien tal rat flea, Xe nop syl la che -opis. Other po ssi ble vec tors are: the dog flea, Cte no -ce pha li des ca nis; hu man flea, Pu lex ir ri tans; mo usefle as, Lep top syl la se gnis, Cte no ph thal mus as si mi lis,and Ce ra to phyl lus hi run di nus. The fle as are im por -tant re se rvo ir ho sts for this pa ra si te; the in fec tedspe ci mens car ry the pa ra si tes thro ugho ut the ir en ti -re li fe [9,12,13].

The infection of rat takes place from invertebratevector through fecal contamination or orally by fleaingestion. The transmission of Herpetosoma trypan -osomes by that way has been experimentally docu -mented [14,15]. It is possible also the in fec tion bythe hurts, on exam ple du ring the com bats be twe enrat in di vi du als [16].

The co ur se of in fec tion in the rat is ty pi cal forpa ra si tic pro to zoa and can be di vi ded in to three pe -riods: the in cu ba tion sta ge; the re pro duc ti ve (mul ti -pli ca tion) sta ge; and the sta ge of „adult” in fec tion.The in cu ba tion sta ge, sin ce the ino cu la tion of theme ta cyc lic forms of pa ra si te and the ap pe aran ce ofthe try pa no so mes in the blo od, la sts 1–7 days. Thisti me the me ta cyc lic try po ma sti go tes trans form in toepi ma sti go tes, which are the re pro duc ti ve ly com pe -tent form of the pa ra si te in the ver te bra te ho sts [5,9].

In the re pro duc ti ve (mul ti pli ca tion) sta ge nu me ro -us di vi sions of pa ra si tes can be ob se rved. Thus the irnum ber ra pi dly grows, to 300 000 in di vi du als in 1 ml.This pe riod la sts 10–25 days, and cha rac te ri zed byexxten si ve va ria tions of pa ra si tes in si ze and bo dypro por tion, due to the si mul ta ne ous oc cur ren ce ofyoung, adults and di vi ded in di vi du als [9,17]. Con tra -ry to com mon ly known Sa li va ria try pa no so mes ofNan no mo nas and Try pa no zo on, di vi ding in to twoyoung spe ci mens, Her pe to so ma Ster co ra ria pro du ces8–12 spe ci mens. T. le wi si di vi des at the epi ma sti go testa ge.The di vi sion ta kes pla ce in the blo od, epi ma sti -go tes do not mi gra te to the in ter nal or gans. The

young in di vi du als are epi ma sti go tes. They grow, andafter re aching full si ze, they start the next di vi dingcyc le, or trans form in try po ma sti go te forms. Try po -ma sti go tes are con si de red as adult sta ge, and they donot di vi de in mam mal or ga nism [12, 18].

The next pe riod – adult sta ge – me ans the ces sa -tion of mul ti pli ca tion and the growth ar rest. An im -pul se for the get ting of in fec tion from the ple omor -phic re pro duc ti ve sta ge in to the not re pro duc ti vemo no mor phic sta ge is the acqu ire ment of the re si -stan ce by the host. The im mu no lo gi cal re spon secon si sts in the com bi ned ac tion of abla stin and try -pa no ci dal an ti bo dies and it is di rec ted aga inst thesur fa ce an ti gens of epi ma sti go te and the di vi dingforms. In the first pe riod of this pha se, the an ti bo -dies do not kill pa ra si tes, but block the ir mul ti pli ca -tion and in du ce the trans for ma tion from the epi ma -sti go te form in to the try po ma sti go te. On ly in nextsta ges epi ma sti go tes, ha ving no ti me left for trans -for ma tion are kil led. Adult try po ma sti go te forms re -ma in in tact, but the ir num bers in the blo od al so gra -du al ly de cre ase [18,19]. This pe riod la sts from oneto ma ny we eks at the end of which ti me the try pa no -so mes com ple te ly di sap pe ar from the blo od. On ly inthe ca se of la tent in fec tions few epi ma sti go te formsre ma in hid den in ca pil la ry ves sels and cells of thekid ney’s co re and in the sple en [17,18,20].

Mam mal sacqu ire per ma nent im mu ni ty, thus there ma ined try po ma sti go tes are not ca pa ble of re sto -ring the pa ra si te’s po pu la tion, and they can be on lya so ur ce of the in fec tion for blo od suc king in ver te -bra tes. It sho uld be em pha si zed that, except im mu -no lo gi cal response, the in cre ase of the try pa no so -mes num ber can be li mi ted in the blo od by the unk -nown in ter nal re gu la to ry me cha ni sms. They do notal low to the rapid in cre asing of the po pu la tion of thepa ra si te which wo uld be able to thre aten to the li feof the host [21].

Ma te rials and me thods

Her pe to so ma try pa no so mes, used in this stu dy,we re iso la ted from the fresh blo od of na tu ral ly in -fec ted rats, Rat tus no rve gi cus in the War sza wa sub -urbs in Mi la nó wek (3 in di vi du als, 1♂ and 2♀, inthis 2 in fec ted 1♂ and 1♀) and in rats cap tu red inthe De er Farm in Ko se wo Gór ne, Ma zu rian Di strict(5 in di vi du als, 2 ♂ and 3♀, 1 ♂ in fec ted). All in fec -ted rats we re ju ve ni les not exce eding 130 g of bo dywe ight. No cli ni cal symp toms in in fec ted ani malswe re ob se rved. Blo od from rats was col lec ted fromthe tip of the ir ta ils, using he pa ri ni sed ha ema to crit

250 G. Karbowiak et al.

tu bes and sub se qu en tly exa mi ned for the pre sen ceof try pa no so mes. The blo od sme ars we re fi xed withme thyl al co hol and sta ined with Giem sa. Blo odsme ars we re scan ned at a ma gni fi ca tion of 1200× byli ght mi cro sco py co upled with a com pu ter and vi deoca me ra, using an Ana ly sis Pro 2.11 pro gram. Mor -pho me tric ob se rva tions fol lo wed the no menc la tu reand me tho do lo gy of Ho are [5]. One hun dred adult,try po ma sti go tes we re me asu red. Me asu re ments andcal cu la ted in di ces we re com pa red with tho se ofT. le wi si from R. no rve gi cus and from R. rat tus gi -ven by other au thors (Ta ble 2 and 3).

The try pa no so mes in ten ded for trans mis sionelec tron mi cro sco py we re fi xed in 2.5% (w/v) glu ta -ral de hy de so lu tion in 0.05 M so dium ca co dy la tebuf fer, pH 7.4, con ta ining 0.12 M su cro se and 5 mMCaC l2. After wa shing in ca co dy la te buf fer and post -fi xa tion in 2.0% (w/v) osmium te tro xi de in ca co dy -la te buf fer for 1 h at 4°C, the spe ci mens we re rin sedand de hy dra ted thro ugh an ascen ding se ries of etha -

nol trans fer red to ab so lu te ace to ne and em bed ded inEpon re sin. Ul tra thin sec tions we re sta ined usingura nyl ace ta te and le ad ci tra te [22]. Mi cro gra phswe re ta ken with a JEM 100B elec tron mi cro sco pe(80 kV).

Re sults

The try pa no so mes fo und we re ma in ly in try po -ma sti go te sta ge (Figs. 1–9). The re we re al so fewepi ma sti go tes. The mor pho lo gi cal fe atu res and si zeof try po ma sti go tes in all lo ca li ties we re si mi lar. Bo -dy length was 15.45–23.64 µm, width 1.3–2.32 µm.The un du la ting mem bra ne was mo de ra te de ve lo ped.The free fla gel lum was 4.93–11.51 µm (me an 8.09)long. The nuc leus was si tu ated at the an te rior part ofthe cell bo dy (NI=1.59). Ki ne to plast was oval andlo ca ted ne arer to the po ste rior end of the bo dy thanto the nuc leus. The bo dy si ze and mor pho lo gy wasal so si mi lar to da ta gi ven by other au thors (Ta ble 2).

Trypanosoma lewisi 251

Table 1. The prevalence of Trypanosoma lewisi in Rattus norvegicus and Rattus rattus at various localities

Rattus norvegicus

Locality Prevalence Author

Khuzestan, Iran 10% Kia et al. [31]

Minas Gerais, Brasil 21.7% Linardi and Botelho [10]

Auckland, New Zealand 12–30% Doré, after Kartman [7]

Wellington, New Zealand 4.6% Laird, after Kartman [7]

Hamacua, Hawaii 11.4% Kartman [7]

Baghdad, Iraq 2.27% El-Shenawi, after Molan and Hussein [32]

Baghdad, Iraq 17.24% Molan and Hussein [32]

Khuzestan, Iran 10% Kia et al. [31]

Windam, India 41.2% Saxena and Miyata [13]

Rattus rattus

Locality Prevalence Author

Madagascar 11.5% Laakkonen et al. [24]

Hamacua, Hawaii 22.2% Kartman [7]

Maharashtra, India 28.9% Mourya et al. [29]

Baghdad, Iraq 11.80–16.26% El-Adhami, after Molan and Hussein [32]

Baghdad, Iraq 7.07% Molan and Hussein [32]

Kuala Lumpur, Malaysia 21.7% Zainal-Abidin and Noor [17]

252 G. Karbowiak et al.

Figs. 1–9. Light micrographs of Giemsa-stained bloodstream trypomastigotes of Trypanosoma (Herpetosoma) lewisifrom R. norvegicus in Poland. T. lewisi has a long thin posterior end, with a subterminal ovale kinetoplast, the nucleusis in the anterior part of the body flagellum is free. Scale bar=10 µm.

Blo od stre am forms of Try pa no so ma le wi si fromRat tus no rve gi cus ul tra struc tu ral ly are si mi lar toblo od stre am forms of other try pa no so ma tid pa ra si -tes [5, 20, 23–26]. They are bo un ded by a pla smamem bra ne 8–10 nm thick (Fig. 13). A sur fa ce co atwas pre sent on the pla sma mem bra ne. Its thick nesswas va ria ble at dif fe rent parts of the bo dy (4–19nm). This is con si stent with the re sults of pre vio usul tra struc tu ral stu dies of ster co ra rian try pa no so messuch as T. cru zi [27, 28]. The cy to ske le ton is cha rac -te ri zed by a sub pel li cu lar cor set of mi cro tu bu les, 25nm in dia me ter. They are lo ca ted 7–11 nm be lowthe pla sma mem bra ne, the di stan ce be twe en the mi -cro tu bu les is 13–25 nm (Figs. 12, 13). In the are awhe re the fla gel lum extends thro ugh the pla sma

mem bra ne one or mo re mi cro tu bu les may be lac -king. It was ob se rved that the num ber of mi cro tu bu -les is re la ted to the dia me ter of the cell. At the po -ste rior and an te rior re gions of the try po ma sti go testhe num ber of mi cro tu bu les is smal ler.

Rod -li ke ki ne to plast as so cia ted with a mi to chon -drion was lo ca ted clo se to the po ste rior end of thetry po ma sti go te bo dy (Figs. 1–9) and far from thepo ste rior end in epi ma sti go te forms (Figs. 10, 14).The sin gle mi to chon drion with well de ve lo ped pla -te -li ke cri stae for med pe ri phe ral ly lo ca ted ca nalrun ning the length of the cell bo dy (Fig. 17a). Innuc leus a pro mi nent, cen tral ly lo ca ted nuc le olus andpe ri phe ral chro ma tin are se en (Figs. 15, 17a). It wasob se rved that T. le wi si di vi ded as epi ma sti go tes

(Figs. 17a, b, c, d) . The Gol gi ap pa ra tus is si tu atedat the an te rior part of the cell bo dy. It was com po -sed of 7–8 flat te ned ci ster nae (Fig. 16). Small ve sic -les we re ob se rved in the re gion of the Gol gi ap pa ra -tus. The ro ugh en do pla smic re ti cu lum was well de -ve lo ped for ming a cha rac te ri stic ci sterns (Figs. 13,16). Free ri bo so mes we re nu me ro us in the cy to -plasm (Fig. 11). The va cu oles and small ve sic les arese en thro ugho ut the cy to plasm (Fig. 11). They dif -fer in sha pe, di men sions and elec tron den si ty. Co -ated gly co so mes with an elec tron den se ma trix we -

re scat te red thro ugho ut the cy to plasm (Figs. 11, 16).The cy to plasm al so con ta ined lar ge di ge sti ve va cu -oles. Struc tu re of the ki ne to so me, fla gel lar po cketand fla gel lum do not dif fer from the ty pe de scri bedin blo od stre am ster co ra rian try po ma sti go tes.

Di scus sion and ge ne ral conc lu sions

Ana ly sis of the li ght mi cro sco pic and ul tra struc -tu ral da ta con fir med that the pa ra si tes fo und in theblo od of the Rat tus no rve gi cus in Po land we re Try -

Trypanosoma lewisi 253

T. lewisi by Karbowiakand Wita [6]

T. lewisi by Taliaferro[4] Baltimore, USA

T. lewisi by Kartman[7] Island of Hawaii

T. lewisi byMansfield [18]

PK mean±SD 3.01±0.70 4.27±0.04

range 1.11–4.33 –

KN mean ±SD 8.93±0.61 10.85±0.02

range 7.27–10.24 –

PN mean±SD 11.94±0.78 15.12* 15.0

range 9.84–13.38

NA mean±SD 7.82±1.54 9.51±0.05 8.8

range 4.42–10.65 – –

BL mean±SD 19.76±1.97 24.63 23.8 23.1

range 15.45–23.64 –

FF mean±SD 8.09±1.51 6.62±0.07 7.4 7.5

range 4.93–11.51 – – 7.2–7.8

L mean±SD 27.84±1.30 31.25±0.06 31.2 30.6

range 24.46–30.39 – – 21.0–36.5

N mean±SD 2.11±0.28 2.1

range 1.30–2.75 –

W mean±SD 1.77±0.24 1.59±0.02 1.9 –

range 1.30–2.32 – – 1.5–2.2

KI mean±SD 1.34±0.25 1.39 1.5

range 1.13–1.50 – –

NI mean±SD 1.59±0.33 1.59 1.7 –

range 1.11–2.58 – 1.2–2.0

FF:BL mean±SD 2.56±0.67 3.72 3.08

range 1.43–4.26 –

Table 2. Dimensions (µm) of Trypanosoma lewisi trypomastigotes from Rattus norvegicus (by various authors)

*Shadow fields – calculated here on the basis of original dataExplanations: PK – distance between posterior end of body and kinetoplast; KN – distance between kinetoplast and nucleus centre;PN – distance between posterior end of body and nucleus centre; NA – distance between nucleus centre and anterior end of body;BL – body length; FF – length of free flagellum; L – total length; W – width of body; N – length of nucleus; NI – nucleus index(NI=PN/NA); KI – kinetoplastic index (KI=PN/KN); FF:BL – flagellar index (=BL/FF).

254 G. Karbowiak et al.

14

Fp

F Fp

MKp

R

F

Spm

M

Kp

M

Tz

Gl

R

M VeGer

F

Mt 1110

12 13

PmSc

15M

En

N

Chr

Ne

Ger

F

Fp

Ki

F

Figs. 10–17. Transmission electron micrographs of Trypanosoma (Herpetosoma) lewisi – bloodstream trypanosomes.Figs. 10–11. Details of the oblique (10) and transverse (11) section of epimastigote form showing the flagellum,kinetoplast, mitochondrion. Glycosomes and membrane bound vesicles in the flagellar pocket region also are visible.The cytoplasm is filled with numerous free ribosomes. Scale bar=0.2 µm.Figs. 12–13. Section of the flagellum and of the part of surface of trypomastigote form showing subpellicularmicrotubules reinforcing the plasma membrane which bears a surface coat. Scale bar=0.1 µm. Fig. 14. Longitudinal section of anterior region of the epimastigote showing details of the flagellum, transitional zoneand kinetosome. The kinetoplast in the expanded part of the mitochondrion is observed in close association tokinetosome. Scale bar=0.3 µm.Fig. 15. The nucleus with the central endosome, peripheral chromatin and double nuclear envelope is demonstrated.Scale bar=0.3 µm.

Trypanosoma lewisi 255

Fig. 16. Section through the trypanosome showing the glycosome (Gl), granular endoplasmic reticulum (Ger) andGolgi apparatus with elongate cisternae and Golgi vesicles are demonstrated. Scale bar=0.5µm.Figs. 17a, b, c, d. Section of dividing forms of epimastigote. Abbreviations as for other figures. Scale bar=0.5 µm forFigs. 17a, b. Scale bar=1.0 µm for Figs. 17c, d.Abbreviations for all figures Chr – chromatin, En – endosome, F – flagellum, Fp – flagellar pocket, Ger – granularendoplasmic reticulum, Gl – glycosome, Go – Golgi apparatus, Gv – Golgi vesicle, Ki – kinetosome, Kp – kinetoplast, M – mitochondrion, Mt – microtubules, N – nucleus, Ne – nuclear envelope, Np – nuclear porc,Pm – plasma membrane, R – free ribosomes, Sc – surface coat, Tz – transitional zone, Ve – membrane boundvesicle, Spm – subpellicular microtubules.

pa no so ma le wi si. It was not po ssi ble to com pa re ofall mor pho me tric va lu es of blo od stre am try po ma sti -go tes from R. no rve gi cus from Po land with tho seda ta ob ta ined by other au thors for T. le wi si fromR. no rve gi cus and R. rat tus (see ac com pa ny ing Ta -bles 2 and 3).

The me an va lu es of PK, KN, PN, NA, BL, L andKI pa ra me ter in try pa no so mes from Rat tus no rve gi -cus from Po land we re smal ler that the me an va lu esgi ven by Ta lia fer ro [4], Kart man [7] and Mans field[18] (Ta ble 2). On ly the ave ra ge free fla gel lar length(FF) was sli gh tly hi gher and FF:BL ra tio lo wer intry pa no so mes from Po land. The me an length of thenuc leus was the sa me for try pa no so mes from Po -

land and from Ha wa ii [7]. The va lue of the nuc le arin dex (NI=1.59) was iden ti cal as for try pa no so mesfrom USA and smal ler (NI=1.70) than cal cu la ted fortry pa no so mes from Ha wa ii. Mans field [18] re por tedon col lec ti ve gro up of try pa no so mes ga ve on ly theran ge of NI in dex wi tho ut me an va lue. The se va lu -es of the nuc le ar in dex sho wed that nuc lei of de tec -ted try pa no so mes we re lo ca ted in the an te rior part ofthe bo dy. The ki ne to plast in try pa no so mes fromR. no rve gi cus from Po land was at a smal ler di stan -ce (me an 3.01 µm) from the po ste rior end (PK) thanin try pa no so mes (me an 4.27 µm) from R. no rve gi -cus from USA [4]. Al so ki ne to pla stic in dex (KI),used to de fi ne the po si tion of ki ne to plast, de ri ved

256 G. Karbowiak et al.

Indices T. lewisi by Kartman [7]

Island Hawaii T. lewisi by Mourya et al. [29]

India T. lewisi by Laakkonen et al. [24]

Madagascar

PK mean 4.95

range 4.70–5.50

KN mean 9.10

range 8.65–9.75

PN mean 14.40* 14.00

range – 13.50–14.55

NA mean 8.3 5.17

range – 4.35–7.05

BL mean 22.70 19.20

range – 17.9–21.20

FF mean 7.3 6.06

range – 6.00–6.25

L mean 30.00 35.6 25.26

range – – 23.85–27.20

N mean 2.1 2.97

range – 2.87–3.00

W mean 1.1 1.76

range – 1.68–1.90

KI mean 1.55

range 1.49–1.64

NI mean 1.73 2.82

range – 2.01–3.16

FF:BLmean 3.11 3.17

range – 2.98–3.53

Table 3. Dimensions (µm) of Trypanosoma lewisi trypomastigotes from Rattus rattus (by various authors)

*Shadow fields – calculated here on the base of data publicated on the basis of original data. Explanations: see Table 2.

from our try pa no so mes was lo wer than cal cu la tedfor try pa no so mes from USA [4] (me an 1.39) and forco lec ti ve gro up of T. le wi si [18] (me an 1.5) and sho -wed that all com pa red spe ci mens had a ki ne to plastlo ca ted ne ar the po ste rior end of the bo dy.

When the mor pho me tric va lu es of T. le wi si fromR. no rve gi cus [4,6,7,18] (Ta ble 3) we re com pa redwith the sa me pa ra me ters of T. le wi si from R. rat tus[7,24,29] (Ta ble 3) we re ve aled ma ny si mi la ri tiesand so me dif fe ren ces in mor pho me tric me asu re -ments of try pa no so mes from the se dif fe rent ho sts.The me an va lu es of PK, KN, PN, N, KI and NI pa -ra me ters in try pa no so mes from R. no rve gi cus fromPo land we re smal ler that the se me an va lu es gi venby La ak ko nen et al. [24] for try pa no so mes fromR. rat tus (Ta ble 3). The va lue of the nuc le ar in dex(NI=1.59) sho wed that nuc lei in our spe ci mens we -re lo ca ted mo re po ste rior ly than nuc lei in T. le wi sifrom R. rat tus (NI=2.82). Ki ne to pla stic in dex (1.34and 1.55, re spec ti ve ly) sho wed that all spe ci menshad a ki ne to plast ne ar the po ste rior end of the bo dy.The ave ra ge free fla gel lar length (FF) was hi gherand FF:BL ra tio lo wer in try pa no so mes from Po -land. Our re sults sho wed hi gher me an va lu es of NA(7.86 µm) and L (25.26 µm) than ha ve be en fo und inR. rat tus by La ak ko nen et al. [24]. The me an length(BL) and width of the bo dy (W) we re si mi lar for try -pa no so mes from both host spe cies.

Kart man [7] re por ted on try pa no so mes fromR. rat tus in Is land Ha wa ii. The me an va lu es of PN,NA and BL gi ven by Kart man [7] we re hi gher thanthe me an va lu es for try pa no so mes from R. no rve gi -cus from Po land and smal ler than gi ven by Ta lia fer -ro [4], Kart man [7] and Mans field [18] al so for try -pa no so mes from R. no rve gi cus. The me an of to tallength (L) of T. le wi si from R. rat tus [7] was sli gh -tly hi gher than the me an va lue for in ve sti ga ted by ustry pa no so mes and al most the sa me as the da ta gi venby Ta lia fer ro [4], Mans field [18] and Kart man [7]for R. no rve gi cus. In our opi nion the re are no si gni -fi cant dif fe ren ces in L and BL va lu es in try pa no so -mes T. le wi si from R. no rve gi cus and R. rat tus be -cau se dif fe ren ces in the ran ge of length me asu re -ments we re not se en. On ly the ave ra ge free fla gel larlength (FF) was sli gh tly lo wer and FF:BL ra tio hi -gher in try pa no so mes from Po land. The me an lengthof the nuc leus was the sa me for try pa no so mes fromboth host spe cies. The va lue of the nuc le ar in dex(NI=1.73) sho wed that nuc lei in try pa no so mes fromIs land Ha wa ii we re lo ca ted mo re an te rior ly thannuc lei in our spe ci mens (NI=1.59).

Mo urya et al. [29] re por ted on try pa no so mes

from R. rat tus in In dia ga ve on ly the me an of va luefor bo dy length (36.6 µm). This va lue is hi gher thanva lu es of bo dy length, gi ven by other au thors [4, 6,7,18,24] for T. le wi si from R.no rve gi cus and R. rat -tus.

The re sults of our in ve sti ga tions show that try pa -no so mes pa ra si ti zing the R. no rve gi cus from Po landap pe ar to be smal ler than T. le wi si from R. no rve gi -cus [4,7,18] and from R. rat tus [7,24,29]. In our opi -nion the re are no si gni fi cant dif fe ren ces in mor pho -me tric va lu es gi ven in the de scrip tions of T. le wi siby se ve ral au thors. Try pa no so mes from the ratsshow con si de ra ble pla sti ci ty in mor pho me tric cha -rac ters al tho ugh the small dif fe ren ces in me asu re -ments re por ted by dif fe rent au thors may be re la tedto the tech ni qu es used, and to the sta ge of in fec tionwhen the or ga ni sms we re exa mi ned, i.e., chro nic orre cent in fec tion.

Our in ve sti ga tion of the fi ne struc tu re of T. le wi -si from R. no rve gi cus from Po land exhi bi ted ty pi caltry pa no so me ul tra struc tu re [5,20,23,24,30] and in -di ca ted a strong si mi la ri ty be twe en this try pa no so -me and other ster co ra rian spe cies.

In our su rvey of en do pa ra si tes of rats, we fo undthat try pa no so me T. le wi si is a co smo po li tan spe ciesand a qu ite com mon pa ra si te of Rat tus no rve gi cusin Po land. No si gns of pa tho ge ni ci ty we re ob se rvedin rats in fec ted with try pa no so mes. The ob se rva -tions of try po ma sti go te forms of T. le wi si li ving inthe host’s blo od con fir med low ple omor phism ofthis pa ra si te [6,9]. The ple omor phism is pro ba blymo re lin ked to va ria bi li ty of de ve lop men tal formsthan dif fe ren ces be twe en dif fe rent stra ins. In ma nyca ses the mor pho lo gi cal dif fe ren tia tion is in cor re la -tion with the age of try pa no so mes. Ta lia fer ro [4]sho wed, that va ria tions in the si ze of sin gle stra insadults spe ci mens are sta ti sti cal ly in si gni fi cant.

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Wpłynęło 3 marca 2009Zaakceptowano 8 kwietnia 2009

258 G. Karbowiak et al.