Helminth Fauna of the Golden Mesocricetus auratus in Brazil

ROBERTO MAGALHÃES PINTO, DS,* LUCINEIDE GONÇALVES, MS, DELIR CORRÊA GOMES, DS, AND DELY NORONHA, BS

Helminth fauna of conventionally maintained from institutional houses that supply the research community with laboratory and from an openly kept control group, randomly purchased in a pet shop in the State of Rio de Janeiro, were evaluated and compared. Necropsied animals from institutional suppliers were infected with the oxyurid nematodes Syphacia criceti and S. mesocriceti and with the cestode Rodentolepis nana; those from the pet shop were infected with S. mesocriceti and R. nana. These are the first morphometric data that are based on Brazilian samples of these species parasitizing hamsters. Mesocricetus auratus is a newly recorded host for S. criceti, previously recovered from Oryzomys subflavus and Calomys callosus in Brazil. The potential of pet and laboratory hamsters in the spreading of helminth infections to humans is also considered.

Because of the role laboratory animals play in the evaluation bran wheat, bran soya, leguminous hay, ground corncob, cal- of several biological parameters in scientific research and in light cite limestone, bicalcium phosphate, premixed amino acids, of the program established to control the sanitary conditions of vitamins, and minerals; PR 145300104, Ministry of Agriculture, Brazilian institutional animal houses, we have developed proce- Colombo, Paraná, Brazil) and filtered water from nursing bottles dures to provide a reliable survey of the helminth fauna occurring adapted to the covers. Bedding and chow were sterilized (heated in several animal models. The models we targeted are commonly for 20 min at 110ЊC) only for animals in group A. The tempera- maintained but not often evaluated, considering the few data ture of the animal room was maintained at 18 to 22ЊC. Housing on the parasites they may harbor. The present approach is re- was in accord to Brazilian guidelines for the care and use of lated to nematodes and cestodes collected in hamsters from two laboratory animals (11). institutional animal houses and a pet shop in Rio de Janeiro. The hamsters from the pet shop (weight, 70 to 90 g; age, 6 to Hamsters are used mainly in assays related to experimental 9 weeks) were kept together in 95.0 ϫ 51.0 ϫ 35-cm cages simi- infections (1, 2), pathology (3-5), host-parasite relationships (6), lar to those used in the animal houses. They received ad libitum immune responses, immunodiagnoses (7), and drug therapies Labina pellets (corn, wheat bran, soya bran, meat flour, raw rice (8). In addition, pet shop hamsters were investigated as a com- bran, calcium carbonate, bicalcium phosphate, salt, premixed parative outside group, because little attention has been given amino acids, vitamins, and minerals; Agribands Purina do Brasil to the possibility of acquiring parasitic infections from Ltd., Itaguaí, Rio de Janeiro, Brazil) and untreated water from obtained from commercial sources. Further, the general popu- glass containers on the bottom of the cage. The cages were openly lation probably is unaware of any threat of helminth infection maintained at room temperature for 3 days after they were de- from pet rodents. Results obtained thus far add new data to the livered to the pet shop by a farm supplier. Husbandry procedures previous major studies of helminths that parasitize laboratory at the farm were the same as those adopted in the pet shop. animals in Brazil (9, 10). This report is important because para- The husbandry practices at the pet shop involved the pres- sites may act as variables, usually unsuspected, in experiments. ence of open food packages next to the animals for sale. Considering that the maximum mean temperatures in Rio de Materials and Methods Janeiro always exceed 32ЊC in the hottest sectors, where abso- Њ Animals. We obtained 30 adult male specimens of the golden lute temperatures higher than 40 C commonly occur (12), the hamster Mesocricetus auratus (weight, 70 to 170 g) from two dif- doors of the shop, although closed at night, were designed to ferent institutional animal houses and a pet shop in Rio de provide a large screened window-like to improve ventilation. Janeiro, Brazil. The animals were allocated into groups A, B, Nevertheless, this floor-level entrance permits the free access of and C (10 animals/group) according to their source. The origi- insects, mice, and rats (attracted by the availability of food) into nal source of institutional animals is unknown, but closed the shop, thereby improving the maintenance of the parasite breeding colonies have been maintained in the institutions for life-cycles in the study animals. more than 20 years. Pet shop hamsters were considered as an Parasites. Immediately after their arrival at the laboratory, outside openly kept control group in the comparison of the preva- hamsters were examined for helminths by using a modified anal lence of the various helminths and intensity of parasitism. The swab technique (10) and sacrificed in an ether chamber accord- suppliers were not identified by name, because of ethical rea- ing to ethical procedures (11). The procedures for processing sons. The microbiological status of the animals was not specified. of helminths for study and their classification have been reported Husbandry. Prior to their arrival at the laboratory, the ham- elsewhere (9). “En face” slides were prepared by using jelly sters from the institutional animal houses (weight, 94.5 to 170 mounts (13). Photomicrographs derived from a Axiophot mi- g; age, 10 to 52 weeks) were maintained conventionally in groups crophotographic system (Zeiss, Jena, Germany) using T400 CN of 10 in 40.0 ϫ 33.0 ϫ 16.0-cm plastic cages with stainless-steel film (Kodak, Guadalajara, Jalisco, Mexico). NHR stands for New screened covers and daily changed bedding of pine shavings. Host Record. Studied specimens were deposited in the Animals received ad libitum Nuvital pellets (ground whole corn, Helminthological Collection of the Oswaldo Cruz Institute (CHIOC) either as whole mounts or wet material.

Laboratorio de Helmintos Parasitos de Vertebrados, Departmento de Helmintologia, Instituto Oswaldo Cruz, Av. Brasil 4365, 21045-900 Rio de Janeiro RJ, Brasil Results *Corresponding author Descriptions refer only to the main morphological data of the

Volume 40, No. 2 / March 2001 CONTEMPORARY TOPICS © 2001 by the American Association for Laboratory Animal Science 21 Figure 1. Syphacia criceti. (A) Male, whole body, lateral view. Bar, 0.08 mm. (B) Anterior portion of male, lateral view. Bar, 0.02 mm. (C) Head of female, “en face” view. Bar, 0.01 mm. (D) Eggs “in utero.” Bar, 0.03 mm. (E) Posterior extremity of male, lateral view. Bar, 0.02 mm. (F) Posterior portion of male, lateral view. Bar, 0.07 mm. Bar of Fig. A, common to Figs. B-F. specific diagnosis and are based on the helminths recovered worms, white when alive. Great sexual dimorphism. Males: body, during the present investigation. 1400 to 1600 (mean, 1500) ␮m long, 90 to 100 (mean, 94) ␮m Syphacia criceti Quentin, 1969. (Fig. 1, A-F) wide, with three mamelons on the ventral surface, of which the (i) Morphometrics based on 10 specimens, five males and five anterior is less prominent than are the two posterior. Esopha- females. Oxyuroidea, Oxyuridae. Small, somewhat slender gus, with bulb, 250 to 260 (mean, 255) ␮m long. Nerve ring 110

22 CONTEMPORARY TOPICS © 2001 by the American Association for Laboratory Animal Science Volume 40, No. 2 / March 2001 Figure 2. Syphacia mesocriceti. (A) Male, whole body, lateral view. Bar, 0.1 mm. (B) Anterior portion of female, lateral view. Bar, 0.03 mm. (C) Eggs “in utero.” Bar, 0.02 mm. (D) Head of female, “en face” view. Bar, 0.01 mm. (E) Posterior portion of male, lateral view. Bar, 0.2 mm. Bar of Fig. A, common to Figs. B-E. to 144 (mean, 130) ␮m from anterior end and excretory pore caudal papillae present. Cloacal aperture 138 to 140 (mean, 139) 460 to 470 (mean, 465) ␮m from anterior end. Single spicule, ␮m from posterior end. 78 to 80 (mean, 79) ␮m long. Gubernaculum 30 to 32 (mean, Females: body 3400 to 3800 (mean, 3500) ␮m long, 210 ␮m 31) ␮m long, with a hook-shaped distal process. Three pairs of wide. Esophagus, with bulb, 360 to 370 (mean, 366) ␮m long.

Volume 40, No. 2 / March 2001 CONTEMPORARY TOPICS © 2001 by the American Association for Laboratory Animal Science 23 Figure 3. Rodentolepis nana. (A) Scolex with armed rostelum. Bar, 0.02 mm. (B) Mature proglottids. Bar, 0.07 mm. (C) Gravid proglottids. Bar, 0.07 mm. (D) Eggs “in utero.” Bar, 0.02 mm. Bar of Fig. A, common to Figs. B-D.

Nerve ring 160 to 190 (mean, 173) ␮m from anterior end and mounts) and 33,875 (wet material). excretory pore 360 to 540 (mean, 462) ␮m from anterior end. Syphacia mesocriceti Quentin, 1971. (Fig. 2, A-E) Vulva 840 ␮m from anterior extremity. Eggs 111 to 120 (mean, (i) Morphometrics based on 10 specimens, five males and five 116) ␮m long, 43 to 48 (mean, 46) ␮m wide. Anus 360 to 390 females. Oxyuroidea, Oxyuridae. Small, thick worms, white when ␮m from posterior end. alive. Cephalic inflations conspicuous. Great sexual dimorphism. (ii) Taxonomic summary. Host: Mesocricetus auratus Males: body 1080 to 1500 (mean, 1300) ␮m long, 80 to 90 (mean, (Waterhouse, 1839)-NHR. Site of infection: small intestine. Dis- 85) ␮m wide, with three prominent mamelons on the ventral tribution: Brazil. Specimens studied: CHIOC no. 34,205a-f (whole surface of posterior portion. Esophagus, with bulb, 190 to 210

24 CONTEMPORARY TOPICS © 2001 by the American Association for Laboratory Animal Science Volume 40, No. 2 / March 2001 (mean, 199) ␮m long. Nerve ring 82 to 90 (mean, 87) ␮m from Table 1. Individual distribution of Syphacia criceti (Sc), S. mesocriceti (Sm), and anterior end and excretory pore 280 to 324 (mean, 302) ␮m Rodentolepis nana (Rn) worm burdens in hamsters of the investigated groups from anterior end. Single spicule 50 to 65 (mean, 58) ␮m long. Hamster Group A Group B Group C ␮ Gubernaculum 29 to 32 (mean, 30) m long, with a hook-shaped 1 55 (Sm) 36 (Sc) 384 (Sm) distal process. Three pairs of caudal papillae. Cloacal aperture 2 36 (Sm) 01 (Rn) 125 (Sm) ␮ 140 m from posterior end. 3 0 20 (Sc), 13 (Rn) 96 (Sm) ␮ Females: body 3200 to 5200 (mean, 4500) m long, 150 to 4 0 06 (Sc), 05 (Rn) 25 (Sm) ␮ 180 (mean, 167) m wide. Esophagus, with bulb, 280 to 385 5 02 (Sm) 02 (Rn) 32 (Sm) ␮ ␮ (mean, 343) m long. Nerve ring 125 to 140 (mean, 132) m 6 0 0 16 (Sm) from anterior end and excretory pore 490 to 560 (mean, 526) 7 40 (Sm) 45 (Rn) 149 (Sm), 32 (Rn) ␮ ␮ m from anterior end. Vulva 700 to 830 (mean, 776) m from 8 0 0 143 (Sm) ␮ anterior extremity. Eggs 130 to 140 (mean, 135) m long, 40 to 9 0 02 (Rn) 78 (Sm), 05 (Rn) ␮ ␮ 50 (mean, 45) m wide. Anus 360 m from posterior end. 10 0 0 277 (Sm), 04 (Rn) (ii) Taxonomic summary. Host: Mesocricetus auratus (Waterhouse, 1839). Site of infection: small intestine. Distribu- tion: cosmopolitan. Specimens studied: CHIOC no. 34,206a-d described on the basis of nematodes recovered from Oryzomys (whole mounts)and 33,876 and 33,877 (wet material). subflavus and Calomys callosus in Brazil (14), and its association Rodentolepis nana (Siebold, 1852) Spasskii, 1954. [Hymenolepis with the cestode Rodentolepis nana in animals of group B may be nana, Vampirolepis nana] (Fig. 3, A-D). due to a possible contamination induced by the animal house (i) Morphometrics based on 10 specimens. Cestoda, staff. These personnel were often in close contact with wild ro- Hymenolepididae, Hymenolepidinae. dents, mainly the murid Akodon cursor, which the care-takers Long worms, white when alive. Body flattened. Suckers 50 to captured for the evaluation of its role in the spreading of sylvatic ␮ ␮ 53 (mean, 51) m long, 50 to 58 (mean, 55) m wide. Rostelum zoonoses and which are maintained on campus. Furthermore, well developed, with a circle of about 25 Y-shaped hooks, each common house mice and even brown rats have been observed ␮ 14 to 16 (mean, 15) m long. Proglottids numerous, transversely in the hamster breeding rooms. ␮ elongated: immature forms 260 to 271 (mean, 266) m long, 50 Syphacia mesocriceti commonly parasitizes hamsters and was ␮ ␮ to 62 (mean, 57) m; mature forms 490 to 520 (mean, 503) m described on the basis of specimens recovered from this same ␮ long, 90 to 130 (mean, 108) m wide; and gravid forms 490 to host. The present study confirms its taxonomic status. ␮ ␮ 540 (mean, 510) m long, 210 to 230 (mean, 220) m wide. In light of morphometrics only, S. criceti and S. mesocriceti are ␮ Three testes, 40 to 43 (mean, 41) m long and 40 to 45 (mean, quite similar; nevertheless, males of the former species are more ␮ 42) m wide, arranged in a transverse line, separated into two slender than those of the latter, even under stereoscope micros- ␮ groups by female gonads. Cirrus pouch 70 to 82 (mean, 77) m copy observation. In addition, if “en face” views are evaluated, long. Gravid uterus extending transversely. Eggs 68 to 70 (mean, the differentiation of these species is achieved promptly by ex- ␮ ␮ 69) m long, 50 to 65 (mean, 58) m wide. amining the ventral mamelons or esophagus. The generic name (ii) Taxonomic summary. Host: Mesocricetus auratus for the cestode R. nana, previously referred to either as Hymenol- (Waterhouse, 1839). Site of infection: small intestine. Distribu- epis or Vampirolepis, was adopted according to the differentiation tion: cosmopolitan. Specimens studied: CHIOC no. 34,247 based on the disposition of internal structures (15). (whole mount) and 33,867 (wet material). Interestingly, in a survey of helminths from pet or laboratory The prevalence of parasitism was 40% in group A animals hamsters and mice (16), S. obvelata parasitized both hosts and (institutional source A), 70% in group B (institutional source was associated with R. nana in the hamsters and with R. nana B), and 100% in group C (pet shop). Positive animals from and Aspiculuris tetraptera in the mice. Another outstanding as- group A were parasitized only with S. mesocriceti (133 worms); pect of our findings is the presence of S. obvelata in all investigated those from group B presented the nematode S. criceti (62 worms) animals, as this oxyurid seems to be naturally specific to mice (9, and the cestode R. nana (68 worms) in single or associated in- 10). A similar specificity is observed for S. mesocriceti and ham- fections, whereas all animals of group C were infected with S. sters, except for unexpected outer interferences in the proper mesocriceti (1325 worms), and three animals also presented R. establishment of the infection by this species. Such an interfer- nana (41 worms) associated with these oxyurids (Table 1). ence may have led to the occurrence of a burden of S. criceti Oxyurid eggs were rare in the feces of hosts, and the anal swab (present investigation), perhaps due to a contamination of the devices we used failed to detect the larvae. Therefore, we needed evaluated colony. Perhaps S. criceti, which was not adapted to to euthanize the animals investigated herein. hamsters when the infection was initiated, was able to induce high immune responses against S. mesocriceti in the hosts such Discussion that this parasite was unable to infect them. The first full accounts relating to helminth parasitization of The role of pet animals in the transmission of helm- Brazilian laboratory animals and its influence (because of cross- inth infections to humans has been emphasized strongly (16). reactions due to parasite associations that are either Human R. nana infections have been reported (16) and appear misinterpreted or overlooked) have been reported (9, 10). The to be due to carelessness resulting from misunderstanding of prevalence of helminth infections in inbred and outbred mice the necessary prophylactic procedures for properly handling pet conventionally maintained in institutional animal houses in Brazil rodents. Nevertheless, cases of human infections by Syphaciinae has been studied (1), and an adaptation of the anal swab tech- nematodes are based only on personal communications, and nique used to detection oxyurid infections in mice was proposed there are no available data on these contaminations, which ap- in an attempt to avoid euthanizing these hamsters (10). The pear to be accidental. However, the generic diagnosis of Syphacia present findings address the helminth species parasitizing ham- refers to these nematodes as parasites of rodents and man (17). sters and the comparison of the helminth fauna of conventionally Moreover, because of the lack of morphometric data and of maintained animals with that of hamsters randomly obtained, illustration of internal structures (except for eggs) that would openly kept in a pet shop, and regarded as a control group. facilitate reliable identification, the so-called Syphacia obvelata The unusual finding of Syphacia criceti in hamsters, originally described in hamsters (16) may be, in fact, S. mesocriceti. That

Volume 40, No. 2 / March 2001 CONTEMPORARY TOPICS © 2001 by the American Association for Laboratory Animal Science 25 parasite was proposed (18) based on 23 nematode specimens 3. Al-Nagdy, S. A., M. F. A. Saoud., and N. Y. S. Morcos. 1996. Serum recovered from Mesocricetus auratus and was redescribed 2 years and tissue enzymes and trace elements in hamsters with schistoso- later in hamsters from Canada (19). Furthermore, S. obvelata is miasis mansoni and/or protein energy malnutrition. Qtar Univ. very similar to S. mesocriceti, and these organisms are distin- Sci. J. 16:39-50. 4. Huffman, J. E., R. F. Pekala, M. L. Taylor, et al. 1998. The effects guished primarily through analysis of cephalic structures by of Echinostoma trivolvis infection on the fertility and fecundity of using “en face” mounts. golden hamsters (Mesocricetus auratus) and on their progeny. J. Rodent infections due to the cestode R. nana undoubtedly Helminthol. Soc Wash. 65:266-269. are transferred to humans and vice versa, for although the ces- 5. Mangoud, A. M., T. A. Morsy, M. E. Ramadan, et al. 1998. Renal tode eggs are directly infective to both man and rodents, the changes in golden hamsters experimentally infected with Leishma- parasite, according to its heteroxenous life-cycle, is transmitted nia d. infantum on top of Schistosoma mansoni infection. J. Egypt. through many intermediate hosts, including fleas and tenebri- Soc. Par. 28:183-189. onids. These intermediate hosts become infected by feeding on 6. Mahler, H., N. Ø. Christensen, and O. Hindsbo. 1995. Studies on the reproductive capacity of Schistosoma caproni (Trematoda) in ham- dried fruit, flour, or cereal that have been contaminated with sters and jirds. Int. J. Parasitol. 25:705-710. rodent feces, and small specimens of infected tenebrioids can 7. Monroy-Ostria, A., L. J. Gómez-Gutierrez, R. A. Ramírez, et al. 1992. pass unnoticed as they invade cereal containers. The transfer of Reconocimiento por inmunoelectro transferencia de antigenos de Syphacia spp. from pet or laboratory animals to humans prob- Taenia solium y su larva. Rev. Latinoam. Microbiol. 34:33-38. ably is not rare, even as an accidental infection—the parasites 8. Travi, B., and Y. Osorio. 1998. Failure of albendazole as an alter- likely are overlooked often because of their monoxenous life native treatment of cutaneous leishmaniasis in the hamster model. cycle and lack of alarming symptoms. This point of view is rein- Mem. Inst. Oswaldo Cruz 93:515. forced by the fact that pet shop animals are seldom maintained 9. Pinto, R. M., J. J. Vicente, D. Noronha, et al. 1994. Helminth para- sites of conventionally maintained laboratory mice. Mem. Inst. under acceptable sanitary conditions and, when purchased from Oswaldo Cruz 89:33-40. wholesalers, are not checked (at least in Brazil) for ecto- and 10. Gonçalves, L., R. M. Pinto, J. J. Vicente, et al. 1998. Helminth para- endoparasites prior to their arrival in the pet shops. sites of conventionally maintained laboratory mice. II. Inbred strains The present findings provide reliable data on the helminth with an adaptation of the anal swab technique. Mem. Inst. Oswaldo fauna of a very common pet animal. In addition, in light of the Cruz 93:121-126. close contact (including caressing and even kissing) of children 11. Associação de Proteção Animal. 1989. Código de ética experimen- with hamsters, our findings serve as a warning regarding the tal com animais. SOZED. Rio de Janeiro:1-8. procedures to be adopted in an attempt to avoid the eventual 12. Instituto Brasileiro de Geografia e Estatística. 1998. Anuário estatistico do Brasil. 57:85. rodent-to-man and man-to-rodent transmission of these parasites. 13. Anderson, R. C. 1958. Méthode pour l'examen des nématodes en Considering that hamsters and other rodents are pets in many vue apicale. Ann. Parasit. Hum. Comp. 33:171-172. homes, the likelihood of cross-infections, particularly involving 14. Quentin, J. C. 1969. Étude de nematodes Syphacia parasites de children and mainly due to unhygienic habits, is high. rongeurs sud-americains et leurs corrélations Regarding barriers to infection, we concluded that the prac- biogéographiques avec certaines espèces néartiques. Bull. Mus. Nat. tices of animal house A, particularly of sterilizing bedding and Hist. Nature 41:909-925. chow, were more effective than those of institutional source B. 15. Czaplinski, B., and C. Vaucher. 1994. Family Hymenolepididae Even upon the development of increased parasitic burdens of Ariola, 1899, p. 595-663. In L. F. Khalil, A. Jones, and R. A. Bray (ed.), Keys to the cestode parasites of vertebrates. C. A. B. Interna- the Syphaciinae nematodes, which are monoxenous (20), this tional, Wallingford, UK. practice prevented the installation of the cestode cycle, which is 16. Stone, W. B., and R. D. Manwell. 1966. Potential helminth infec- heteroxenous (21) and has a low potential of transmission. tions in humans from pet or laboratory mice and hamsters. US Public Health Rep. 81:647-653. 17. Vicente, J. J., H. O. Rodrigues, D. C. Gomes, et al. Nematòides do Acknowledgments Brasil. Parte V: Nematòides de mamíferos. Revta. Brasil Zool. 14:1- We thank the institutions for supplying the hamsters, Genilton José 452. Oliveira and Heloisa Maria Nogueira Diniz (Departamento de Ensino, 18. Quentin, J. C. 1971. Morphologie comparée des structures Instituto Oswaldo Cruz, FIOCRUZ) for technical photographic support, céphaliques et génitales des Oxyures du genre Syphacia. Ann. Parasit. and Dr. Robin Overstreet (University of Southern Mississippi) for a re- Hum. Comp. 46:15-60. print. We dedicate this paper in honor of the Oswaldo Cruz Institute, on 19. Dick, T. A., J. C. Quentin and R. S. Freeman. 1973. Redescription the occasion of the centenary of its foundation, May 25th 1900. of Syphacia mesocriceti (Nematoda: Oxyuroidea) parasite of the . J. Parasitol. 59:256-259. References 20. Anderson, R. C. 1992. Nematode parasites of vertebrates. Their development and transmission, p. 1-557. C. A. B. International, 1. Sanchez-Campos, S., M. J. Tùnon, P. Gonzales, et al. 1999. Oxida- Wallingford, UK. tive stress and changes in liver antioxidant enzymes induced by 21. Olsen, O. W. 1974. Animal parasites. Their life cycle and ecology, experimental dicrocelioids in hamsters. Parasitol. Res. 85:468-474. p. 1-562. Dover Publications Inc., New York. 2. Merchant, M. T., L. Aguilar, G. Avila, et al. 1998. Taenia solium: description of the intestinal implantation sites in experimental ham- ster infections. J. Parasitol. 84:681-685.

26 CONTEMPORARY TOPICS © 2001 by the American Association for Laboratory Animal Science Volume 40, No. 2 / March 2001