There is little available data regarding helminths of mammals in the Tibetan Plateau, Qinghai Province, China. This study presents preliminary data obtained from the China-Japan co-operative survey, performed in the summers of 2007 and 2009.Alimentary tracts and viscera of 78 small mammals, including plateau pikas (Ochotona curzoniae) and rodents (Mus musculus, Alticola stoliczkanus, Cricetulus longicaudatus, Meriones meridianus and Phodopus roborovskii), were investigated. Thirty of these animals were negative for helminths. Among the helminth-positive samples, no platyhelminthes (including metacestodes of Echinococcus spp.) or acanthocephalan parasites were obtained. Four nematode genera, including Heligmosomoides, Heligmosomum, Syphacia and Trichuris were obtained from rodents. Four other nematode genera and species, including Ohbayashinem aochotoni, Trichostrongylus retortaeformis, Gradiphiellaochotonae and Cephaluris coloradensis, were obtained from the plateau pika spp. With the exception of C. coloradensis, these were first recorded instances of these species in the pikas. These can be added as newly-recorded nematode parasites in plateau pikas, though none of these are new species, nor do they appear medically relevant.

Tsevegmid K, Motokawa M, Zhang H, Pei J, Asahara M, et al. (2018) A Helminthological Record on Free-Ranging Pikas and Rodents Collected from Tibetan Plateau, China: Preliminary Results. Ann Clin Cytol Pathol 4(4): 1106.

•    Murids
•    Nematodes
•    Pikas
•    Qinghai province
•    Tibetan plateau

Small mammals, such as rodents and pikas, play an important role in the ecosystem of the Tibetan Plateau in the Qinghai Province of China [1. To date, limited data have been collected regarding parasitic helminths of these species, because studies are difficult to conduct in this area [2-4]. Therefore, we present preliminary data from a China-Japan cooperative survey of mammalian species performed in the summers of 2007 and 2009 [5].

Mammals were collected at several sites in Qinghai Province, China, with taking strict rules of the euthanasia and other ethics in both China and Japan into consideration [5]. After then, the fixed alimentary tracts including esophagus, stomach, small large intestines, and viscera including liver, lung, kidney and genital organ shown below were sent to the 1st and correspondence authors. Each location, longitude, and altitude is previously described by Motokawa et al, [5].

The alimentary tracts and viscera from a total of 78 small mammals, including rodents (Mus musculus, Alticola stoliczkanus, Cricetulus longicaudatus, Meriones meridianus and Phodopus roborovskii) and plateau pikas (Ochotona curzoniae) were stored in 70% ethanol solution and examined under a dissecting microscope. Nematodes were cleared in lactophenol solution. Cross-sections were hand-cut, using a surgery scalpel, and used to examine gradients of ridges [6]. Morphological analysis and measurements were performed using a microscope and photo camera (BH2, OLYMPUS).

Thirty of the collected small mammals were negative for helminths. Namely, we have 48 helminth positive materials. Neither platyhelminth nor acanthocephalan parasites were obtained from rodents in this study, although metacestodes of the genus Echinococcus have previously been reported in the plateau region [2-4].

In the present study, only nematodes were found in positive samples. Four genera were found in the small or large intestines of rodents, including Heligmosomoides (Fam. Heligmosomidae; Hosts: C. longicauda, P. roborovskii and A. stoliczkanus), Heligmosomum (Fam. Heligmosomidae; Host: A.sibirica), Syphacia (Fam. Oxyuridae; Hosts: M. musculus, C. longicauda, P. roborovskii, M. meridianus and A. stoliczkanus) and Trichuris (Fam. Trichuridae; Host: A. stoliczkanus). We are currently working to further identify, including molecular biology, these nematodes to a species level, using related references [6,7].

Four separate nematode genera were found in the alimentary tracts of pikas, including:

Ohbayashinem aochotoni (Fam. Heligmosomidae). Locations: Kunlunshan-kuo, Kekexili-di. Site: Small intestine. Male: Body coiled ventrally, length 5.8 mm, width 0.84 mm. Esophagus 0.63 mm in length (Figure 1-1). Nerve ring 0.20 mm and excretory pore 0.24 mm from anterior extremity. Eleven ridges in synlophe of midbody, with five dorsal and six ventral. Lateral ridges absent, dorsal ridges more developed than ventral ridges (Figure 1-2). Spicule length 0.45 mm. Bursa symmetrical (Figure 1-3), anteroand postero-ventral rays, and antero-, postero- and medio-lateral rays from same stem, respectively. Dorsal rays (Figure 1-4) well developed, 0.02 mm in length. Externo-dorsal rays and antero-, postero-andmedio-lateral rays from common base. Female: Body length 10.3 mm, width 0.1 mm. Esophagus length 0.70 mm. Nerve ring 0.17 mm and excretory pore 0.26 mm from anterior extremity. Vulva 0.30 mm from posterior extremity (Figure 1-5). Egg oval, 0.08 mm x 0.04 mm. Vagina vera 0.05 mm in length, vestibule 0.41 mm in length, sphincter 0.054 mm x 0.047 mm. Tail length 0.09 mm, curving usually ventrally, ending in spine. Among known species of the genus Ohbayashinema [8-10], the most similar species was O. ochotoni based on morphologic features of dorsal ray. However, this species has been obtained from different host species as O. dauurica (Mongolia), O. microtus (Nepal) and O. cansas (Gansu, China).

Trichostrongylus retortaeformis (Fam. Trichostrongyloidae). Locations: Xidatang and Kekexili-di. Site: small intestine. Male: Body length 3.9-4.9 mm, body width at midbody 0.06 mm. Esophagus length 0.77 mm. Nerve ring and excretory pore 0.02 mm from anterior extremity (Figure 1-6). Bursa symmetrical, dorsal ray about 3/4 in length of externo-dorsal rays (Figure 1-7,1-8). Spicule length 0.01 mm, gubernaculum 0.007 mm x 0.002 mm (Figure 1-9).Female: Body length 4.4 mm (Figure 1-10), body width at vulva 0.12 mm. Esophagus length 0.67 mm. Nerve ring 0.13 mm and excretory pore 0.15 mm from anterior extremity. Vulva 0.98 mm from posterior extremity, egg 0.063 x 0.030 mm, didelphic (Figure 1-11). These characteristics correspond to T. retortaeformis, a common parasite of wild lagomorphs through the Palearctic region [11,12].

Gradiphiellaochotonae (Fam. Trichostrongyloidae). Localition: Kekexili-di. Site: Stomach. Male: Cervical papillae and buccal capsule present (Figure 2-1), body length 9.3 mm, width 0.5 mm. Esophagus length 0.61 mm. Nerve ring 0.13 mm and excretory pore 0.23 mm–0.26 mm from anterior extremity, respectively. Prebursalpapillae not observed, bursal ray type 2-3, externo-dorsal rays shorter than dorsal rays, spicule length 0.56 mm, gubernaculum absent (Figure 2-2 to 2-4). Female: Body length 15.2 mm, uncoiled, width at midbody 0.82 mm. Esophagus length 0.67 mm. Nerve ring 0.25 mm and excretory pore 0.37 mm from anterior extremity. Cervical papillae and buccal capsule present. Vulva 7.4 mm–8.4 mm from posterior extremity, uterus didelphic, ovejector type I, vestibule length 0.44 mm–0.47 mm, eggs in uterus 0.16 mm x 0.08 mm, tail length 0.43 mm (Figure 2-5 to 2-7). According to Olsen [13], these characteristics correspond to G. ochotonae.

Cephaluris coloradensis (Fam: Heteroxynematidae). Locations: Kunlunshan-kuo, Fenghuoshan, Tuotuohe Gonglu, Kekexili di. Site: Large intestine. Male: Body length 5.7 mm– 7.3 mm, width 0.03 mm, cephalic extremity with cuticular shield developed and pharyngeal cavity reduced (Figure 2-8). Esophagus length 0.5 mm–0.6 mm, esophagus bulb diameter 0.09 mm–0.13 mm. Nerve ring 0.1 mm and excretory pore 0.3 mm–0.5 mm from anterior extremity. Tail length 0.6 mm–0.7 mm, cloaca surrounded by three cushions (Figure 2-9). Female: Body length 7.2 mm–15.4 mm, width 0.5 mm–0.6 mm. Esophagus length 1.0 mm, oesophagus bulb diameter 0.15 mm–0.16 mm. Nerve ring 0.16 mm and excretory pore 0.83 mm–0.93 mm from anterior extremity. Vulva not significantly protruding (Figure 2-9), vulvar opens from anterior extremity 0.39 mm–0.43 mm. Eggs in uterus0.08 mm-0.10 mm x 0.05 mm–0.06 mm, tail0.96 mm–1.36 mm in length (Figure 2-10). The species belongs to the genus Cephaluris, which includes C. alaskensis (Alaska; host Ochotona collaris), C. andrejevi (Kazakhstan; Ochotona alpine), C. collaris (Alaska; Ochotona collaris), C. coloradensis (Colorado; Ochotona princeps), C. hashmi (Quatta; Ochotona rufescensvulturna), C. jtachaehsis (Tibet; Microtus spp.), C.vakhanica, C. chabaudi and C. ochotonae (Ochotona rufescens) [2,14-18]. The specimens correspond most closely to C. coloradensis.

This is the first record of O.ochotoni, T. retortaeformis and G. ochotonae in the pika species. Wang et al. [2], previously reported C. coloradensis and nematodes, including Oesophagostomum sp., Eugenuris schumakowiescsi, Haemonchus sp., Trichuris sp. and Chabertiinae gen. sp., in pikas from the southeastern Qinghai Province. O. ochotoni, T. retortaeformis and G.ochotonae can be added as newly-recorded nematode parasites in plateau pikas, though none of these are new species, nor do they appear medically relevant.

1. Smith AT, Foggin JM. The plateau pika (Ochotona curzoniae) is a keystone species for biodiversity on the Tibetan plateau. Anim Conserv. 1999; 2: 235-240.

2. Wang CH, He H, Li M, Lei F, Root J, Wu Y, et al. Parasite species associated with wild plateau pika(Ochotona curzoniae)in southeastern Qinghai Province, China. J Wildl Dis. 2009; 42: 288-294.

3. Xiao N, Jiamin Q, Nakao M, Li T, Wen Y, Chen X, Schantz PM, et al. Echinococcus shiquicus n.sp., a taeniid cestode from Tibetan fox and plateau pika in China. Internl J Parasitol. 2005; 35: 693-701.

4. Xiao N, Nakao M, Qui J, Budke CM, Giradoux PS, Ito A. Dual infection of animal hosts with different Echinococcusspecies in the eastern Qinghai-Tibet region of China. Am J Trop Med Hyg. 2006; 75: 292-294.

5. Motokawa M, Zhang H, Pei J, Asakawa M, Asahara M, Wen WJ, et al. Small mammals collected from Qinghai Province, China. Biogeography. 2010; 12: 29-37.

6. Durette-Desset MC. Trichostrongyloid nematodes and their vertebrate hosts: Reconstruction of the phylogeny of a parasitic group. Adv Parasitol. 1985; 24: 239-306.

7. Hasegawa H, Sato H, Iwakiri E, Ikeda I, Une Y. Helminths collected from imported pet murids, with special reference to concomitant infection of the golden hamsters with three pinworm species of the genus Syphacia(Nematoda: Oxyuridae). J Parasitol. 2008; 94: 752-754.

8. Durette-Desset MC, Galbraeth K, Hoberg EP. Discovery of new Ohbayshinema spp. (Nematoda: Heligmosomoidea) in Ochotona princeps and Ochotona cansus (Lagomorpha: Ochotonidae) from western North America and Central Asia, with considerations of historical biogeography. J Parasitol. 2010; 96: 569-579.

9. Durette-Desset MC, Ganzorig S, Audebert F,Kamiya M. A new species of the genus Ohbayashinema (Nematoda, Trichostrongylina, Heligmosomoides), parasite of Ochotona daurica (Ochotonidae, Lagomorpha) from Buriatia. Zoosystema. 2000; 22: 667-676.

10. Fukumoto SI, Kamiya M, Ohbayashi M. Ohbayashinema abei sp. (Nematoda: Heligmosomidae) from the northern pika, Ochotona hyperborean Pallas, in Hokkaido, Japan. Jpn J Vet Res. 1986; 34: 233- 240.

11. Asakawa M. A new host and locality for Trichostrongylus retortaeformis (Zeber, 1800) (Nematoda, Trichostrongyloidea: Trichostrongylidae) from the Japanese grass vole, Microtus montebelli (Milne -Edwards) (Rodentia: Microtidae), in Nagano Prefecture, Japan. J Rakuno Gakuen Univ Nat Sci. 1991; 16: 15-20

12. Audebert F, Hoste H, Durette-Desset MC. Life cycle of Trichostrongylus retortaeformis in its natural host, the rabbit (Oryctolagus cuniculus). J Helminthol. 2002; 76: 189-192.

13. Olsen LS. A new species of oxyurid nematode from a pika, Ochotona princeps figginsi. Trans Am Microscop Soc. 1949; 68: 337-341.

14. Gvozdev EV. 1956. On the helminth fauna of Ochotona sp. of Kazakhstan. Tr Inst Zool Akad Nauk Kaz SSR. 1956; 5:98-104.

15. Gvozdev EV. New nematodes from Ochotona alpina Pallas. Helminthol. 1966; 7: 273-278.

16. Hobbs RP. A Revision of the Genus Cephaluris Akhtar, 1947 (Nematoda, Oxyuridae) with redescriptions of the North American species. Proc Helminthol Soc Wash. 1976; 43: 151-160.

17. LiCF, Liu Y. A new species of Cephaluris (Oxyurata: Heteroxynematidae). Acta Zootaxa Sin. 1992; 17: 156-159.

18. Seesee FM. The helminth parasites of the pika, Ochotona princepsprinceps (Richardson, 1828), in northern Idaho. Am Midl Nat. 1973; 89: 257-265.