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Development of Taenia saginata asiatica metacestodes in SCID
mice and its infectivity in human and alternative definitive
Chang, S. L.; Nonaka, N.; Kamiya, M.; Kanai, Y.; Ooi, H. K.;
Chung, W. C.; Oku, Y.
CitationParasitology Research, 96(2): 95-101
RightThe original publication is available at www.springerlink.com
Typearticle (author version)
Hokkaido University Collection of Scholarly and Academic Papers : HUSCAP
S. L. Chang, N. Nonaka, M. Kamiya, Y. Kanai, H. K. Ooi, W. C. Chung, Y. Oku
Development of Taenia saginata asiatica metacestodes in SCID mice
and its infectivity in human and alternative definitive hosts
S. L. Chang, N. Nonaka, Y. Kanai, Y. Oku (Corresponding author)
Laboratory of Parasitology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo
E-mail address: firstname.lastname@example.org
Tel. and fax:+81-11-706-5196
Laboratory of Environmental Zoology, Department of Biosphere and Environmental Sciences,
Faculty of Environmental Systems, Rakuno Gakuen University, Ebetsu 069-8501, Japan
H. K. Ooi
Department of Veterinary Medicine, National Chung Hsing University, 250 Kuo Kuang Road,
W. C. Chung
Department of Parasitology, Taipei Medical University, 250 Wu Hsing Road, Taipei, Taiwan
Abstract: Development of Taenia saginata asiatica metacestodes in SCID mice and its infectivity
in humans, and in golden hamsters and Mongolian gerbils as alternative definitive hosts, were
investigated. Cysticerci were recovered from SCID mice that were subcutaneously injected with
hatched eggs of T. s. asiatica. The morphological changes of cysticerci were observed. The
recovered cysticerci were by fed to gerbils, hamsters and humans, to check for infectivity.
Tapeworms were recovered from gerbils and hamsters that were fed 20 to 45 week-old cysticerci,
and proglottids excretion were observed in human volunteers fed with 45 week-old cysticerci.
However, no tapeworms were recovered from gerbils fed with 10 week-old cysticerci. Our results
suggest that T. s. asiatica oncospheres needed more than 20 weeks to develop to maturity in SCID
mice to be infective to both their natural and alternative definitive hosts.
Keywords: Taenia saginata asiatica; Metacestode; Cysticercus; SCID mice; Alternative host;
Asian taeniasis, caused by Taenia saginata asiatica, was first reported by Oi in 1915 in central
Taiwan (Oi 1915). It has been reported in many other Asian countries such as China (several
provinces), Korea, Indonesia, Thailand, Philippines, Malaysia and Myanmar (Fan et al. 1989, 1990a,
1992a, 1992b; Eom and Rim 1993; Bowles and McManus 1994; Simanjuntak et al. 1997; Zhang et
al. 1999; Fan 2000; Fan et al. 2001; Eom et al. 2002; Ito et al. 2003).
Compared with other human taeniids, the tapeworm of T. s. asiatica has no hook on its rostellum,
which differed from T. solium but is similar to the classical T. saginata (Taenia saginata saginata)
(Fan et al. 1995). However, in the intermediate host, metacestodes of T. s. asiatica parasitize in the
viscera (mostly in the liver) of pigs (Fan et al. 1995; Eom and Rim 2001), whereas T. s. saginata
parasitize in the muscle of cattle (Schmidt and Roberts 2000).
Recently, eggs of T. s. asiatica had been reported to develop into mature cysticerci when injected
into the subcutaneous tissue of severe combined immunodeficiency (SCID) and immunosuppressed
ICR mice (Ito et al. 1997b; Ito and Ito 1999; Wang et al. 1999). The size of the cysticerci recovered
from SCID mice was found to be larger than those in the pigs (Ito et al. 1997a). Moreover, 49% of
the metacestode were seen to be calcified or degenerated in 34 infected pigs at 11 to 97 days
post-infection but no calcification of the metacestodes was observed in the SCID mice at 244 days
post-infection (Wang et al. 2000; Fan et al. 1990c).
Since the SCID mouse has proved to be an experimental intermediate host model for the study of
the development of T. s. asiatica metacestodes, it is necessary to confirm the infectivity of the
cysticerci recovered from SCID mice. Human is the only known natural definitive host of the three
aforementioned human taeniids. In addition, alternative definitive hosts have been used to test for
the infectivity of the cysticerci. Alternative definitive host models for T. solium using golden
hamsters, Mongolian gerbils, chinchillas and gibbons that were orally inoculated with cysticerci
obtained from naturally infected pigs, have been reported. Gravid proglottids were recovered only
from chinchillas and gibbons (Cadigan et al. 1967; Verster 1971, 1974; Maravilla et al. 1998). For T.
s. saginata, sexually mature tapeworms were recovered from gerbils inoculated with cysticerci from
naturally infected cattle (Kamiya et al. 1990). It has also been demonstrated that cysticerci of T.
solium recovered from SCID mice could develop to maturity in hamster albeit only pregravid
tapeworm was observed (Wang et al. 1999). In the present study, we examined the infectivity and
development of T. s. asiatica metacestodes from SCID mice in human and its alternative definitive
hosts, the golden hamsters and Mongolian gerbils.
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