豚および野生イノシシにおけるsarcocystis感染豚および野生イノシシにおけるsarcocystis感染...
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豚および野生イノシシにおけるSarcocystis感染
誌名誌名 動物の原虫病 = Journal of animal protozoosis
ISSNISSN 09157506
著者著者斉藤, 守弘萩原, 晶代
巻/号巻/号 28巻1号
掲載ページ掲載ページ p. 25-30
発行年月発行年月 2013年12月
農林水産省 農林水産技術会議事務局筑波産学連携支援センターTsukuba Business-Academia Cooperation Support Center, Agriculture, Forestry and Fisheries Research CouncilSecretariat
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Journal of Animal Protozooses Vol. 28, No. 1 (2013)〔原著〕 25
Sαrcocystis miescheriαnαinfection in pigs and wild boars in Japan
Morihiro SAITO and Akiyo HAGIW ARA
Meat Inspection Center of Saii抱机αPrefec;切符
(Received 9 Jul., 2012)
Abstract Of 50 fattened and 50 older culled breeding pigs slaughtered in Saitama Prefecture,
Japan from November 2010 to March 2011, three (6%) culled pigs were positive for Sarcocystis
miescheriana, whereas none of the fattened pigs were positive. Three of 48 (6.3%) wild boars (Sus
sucroj包:) captured in Saitama Prefecture from November 2010 to March 2011 were positive for S.
miescheriana. The S. miescheriana cysts had the thick and radially striated wall. Scanning electron
microscopy revealed many villar protrusions 4-5 μm in len民hon也ecyst surface. A dog fed S.
miescheriana infected meat excreted sporocysts in the feces after day 9.
Key words : dogs, pigs, Sarcocystis, wild boars
Journal of Animal Protozooses Vol. 28, No. 1: 25-3α2013
Introduction
Sarcocystis infections have been reported in domestic
pigs and wild boars in various p紅白 ofthe world: Nor-
way, Netherlands, Germany, Hungary, Bulgaria, USSR,
Fiji, Australia, New Zealand, USA, and Brazil12l. In
Japan, there is little information on Sarcocystis infection
of pig and wild boars.9J_
Three species of Sarcocystis have been recorded
from domestic pigs and wild boars : S. miescheriana, S.
suihominis and S.ρore俳lisand their final hosts are
dogs, humans, and cats, respectively2・5l_ In the present
report the frequency of Sarcocystis infections was sur-
veyed in pig and wild boars in Saitama prefecture,
Japan.
Materials and Methods
Pigs : Fifty grams of car世acmuscle and diaphragm
were individually obtained from 50 fattened and 50
older culled breeding pigs slaughtered in Saitama
Prefecture from November 2010 to March 2011.
Wild boars : Fifty grams of cardiac muscle and
diaphragm were individually obtained from 50 wild
・5-18-24Kamiochiai, Chuoku, Saitama, Saitama 338-0001, Japan
boars captured in Saitama Prefecture from November
2010 to March 2011.
Muscle blocks were dissected into approximately 1
×2×0.5 cm in size and examined for cysts in a plane
perpendicular to the long axis of the muscle fibers.
Thereafter the cysts were directly removed from the
blocks under a microscope7l.
Twentyfive fresh cysts from the diaphragm muscles
were measured with a micrometer and examined也e
s甘uctureof the cyst wall. A part of fresh cysts were
fixed wi也 10%formalin and post-fixed with 1 % osmic
acid. Then they were dehydrated in a series of
ethanol and dried at the critical point After platinum
was deposited, the cyst samples were observed with
scanning electron microscope (Nihon Denshi, JSM司35C)
for the superficial structures such as villar protrusions.
For histopathological examination, tissue samples
were removed from infected muscles and fixed with
10% formalin. The specimens were embedded in
paraffin and sectioned. The sections were stained wi也
hematoxylin and eosin and observed under a light
microscope. Another part of the fixed material was
post-fixed with 1 % osmic acid and embedded in epoxy
resin. The resultant ultrathin sections were stained
wi也 ur叩 ylacetate and lead ci甘ate,叩d由enobserved
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26 動物の原虫病 第28巻第l号 (2013)
for the ultrastruture of the cyst wall with a transmis-
sion electron microscope (lOOCX. Nihon Denshi, Japan).
400 g of infected cardiac muscles. All the ingested
dogs were daily examined for sporocysts passed in the
total amount of feces by the flotation method with Two male mongrel dogs, 5-months old, were fed
Fig. 1. Fresh cyst of Sarcocystis miescheriana from diaphragm muscle of a pig (left) and
that of a wild boar (right).×100
Fig. 2. Cross section of a thick-walled cyst of S. misecheriana in diaphragm muscle of a pig (left) and
that of a wild boar. HE stain ×100
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Sarcocystis miescheriana infection in pigs and wild boars in Japan 27
satulated NaCl solution. Fifty sporocysts excreted in
the feces of the animals were observed and measured
with a micrometer under a light microscope.
Result
Three of 50 (6%) culled pigs were positive for
sarcocysts, whereas none of the fattened pigs were
positive. Three of 48 (6.3%) wild boars (Sus sucrofa)
were positive for sarcocysts.
Fresh cysts were 1,080-2,700×78-90 μm in size. All
S訂 cocystshad the radially striated wall, whose thick-
ness ranged from 4 to 5 μm (Fig. 1). These structural
Fig. 3. Transmission electron micrograph of S. miescheri (upper left) and出atof a wild boar (upper right).×10,000 Scanning electron micrograph
of S. miescheriana cyst in diaphragm muscle of a pig : Note palisade-like villar protrusions on cyst wall (lower left) and也atof a wild boar (lower right)×2,000
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28 動物の原虫病 第28巻第1号 (2013)
4際
‘・。. .
,
. ,
,
Fig. 4. A sporocyst of S. miesche1叩naexcreted in feces of dog, which were fed a Sarcocystis
infected raw pork. ×400
feature were also confirmed on histopathological exam-
ination (Fig. 2). Transmission and scanning electron
microscopy showed palisaid-like villar protrusions 4-5
×0.7-lμm in size, on the cyst wall (Fig. 3).
The dogs fed infected meat passed sporocysts in the
9 days after ingestion. Sporocysts were ellipsoidal and
measured 12-13×9.5-10 μm in size (Fig. 4).
Discussion
The incidence rat of Sarcocystis infection is known
to increase with the age of host animals. Boch et al.1)
d巴tectedS. miescheriana cysts in 25.5% of older pigs
and in 9.7% of fattened ones in southern Germany.
Seneviratana et al.10) reported that 12.7% of 55 older
than one year were positive but none of 48 pigs less
than one year old were positive for Sarcocystis sp.,
which was not identified the species but seem to be S.
miescheriana because the sporocysts were recoverd
from dogs fed the infection meat. On the other hand,
it is reported that the infected rate of S. miescheriana
in the pig and the wild boar were both 7% in the latter
half of the 20th century in Japans.9l. Since then, there
is no report until the present study出atrevealed the
infection rate equivalent to past data.
Three species of Sarcocystis have been reported in
pigs : S. miescheriana, S. suihominis, and丘ρore俳Lis,
which utilize dogs, humans, and cats as final hosts,
respctively. These Sarcocystis species can be identified
by the morphological features of cysts, especially the
thickness and structure of their wall. in addition to the
specificity to final hosts and the prepatent period.
Cysts of distinct species have characteristic shapes,
maximal sizes, and surface feature. Most of Sarcocystis
cyst has surface projections, whose size, shape and
arrangement in mature cysts have a constant feature
of species11l Cysts of丘 miescherianaare as large as
1.500 μm long and 200 μm wide. Their walls are 3 to
6 μm thick and appears radially striated. The villar
protrusions on the Sarcocystis wall are up to 5μm long
and l.Oμm wide7l. The cysts isolated in the present
study had the wall structure identical with出oseof S.
miescheriana.
The prepatent period of S. miescheriana reported to
be 9 to 12 days by Erber3l and 9 to 10 days by Rommel
et al.6) Sporocysts of S. miescheriana were reported to
be 12.6×9.6μm, 12.7×10.lμm, and 11.2×8.3 μmin size.
Like these literatures, the dogs fed infected meat
passed sporocysts, 12-13×9.5-10 μmin size, in 9 days
after ingestion.
Consequently,出巴 presentspecies was identical to S.
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Sarcocystis miescheriana infection in pigs and wild boars in Japan 29
miescherians based on the morphological characteristics
of cysts and sporocysts as well as the final host species.
It is known that human is the final host for S.
suihominis and infected by eating undercooked cyst-
laden meat from pigs and wild boars as an intermediate
host2・4.5l_
In the present study, none of pigs and wild boars
were infected with S. suihominis. Because of the im-
portant issue in the view of meat hygiene, continuous
the investigation of Sarcocystis infection in pigs and
wild boars may be needed.
References
1) Boch, J., Mannewitz, U., Erber, M. (1978)
Sarkospridien bei Schlachtschweinen in
Suddeutschland. Berl Muench Tieraerztl
Wochenschr. 91, 106-111.
2) Dubey, J.P. (1976) A review of Sarcocystis of do-
mestic animals and of other coccidian of cats and
dogs. J. Am. Vet Med. Assoc. 169, 1061-1078.
3) Erber, M. (1977) Moglichkeiten des Nachweises
und Differenzierung vor zwei Sarcocystis Arten des
Schweines. Berl Muench. Tieraerztl. W ochenschr.
90, 480-482.
4) Heydorn, A.O. (1977) Beitrage zum Lebenszklus der
Sarkosporidien. 9. Entwicklungszyklus von
Sarcocystis suihominis n. spec. Berl. Muench.
Tieraerztl. W ochenschr. 90, 218-224.
5) Ito, S. (1985) Life cycle of Isosporan coccidian. In :
Progress in Veterinary Science 1985,. Kindai
Shupan. Tokyo. 71-105 pp.
6) Rommel, M., Heydorn, A.O., Fischle, B. and Gestrich,
R. (1974) Beitrage zum Lebenszyklus der
Sarkosporidien. 5. Weitere Endwirte der
Sarkosporidien von Rind, Schaf, und Schwein und
die Bedeutung des Zwishenwirtes fur die
Verbreitung dieser Parasitose. Berl. Muench.
Tieraerztl. Wochenschr. 87, 392-396.
7) Saito, M., Hachisu, K., Iwasaki, K., Nakajima, T.,
Watanabe, A., Moriya, H. and Itagaki, H. (1984) A
new simple method for detection of bovine Sarcocystis
cysts. J. Jpn Vet Med. Assoc. 37, 158-162.
8) Saito, M., Nakajima, T., Watanabe, A. and Itagaki,
H. (1986) Sarcocystis miescheriana infection and its
仕equencyin pigs in Jpn. J. Vet Sci. 48, 1083-1090.
9) Saito, M., Shibata, Y., Kubo, M. and Itagaki, H.
(1998) Sarcocysti miescheriana infection in wild
bo紅 s.J. Jpn. Vet Med. Assoc. 51, 679-682.
10) Seneviratana, P., Edward, A.G., DeGiusti, D.L. (1975)
Frequency of Sarcocystis spp. in Detroit, Metro-
politan area, Michigan. Am. J. Vet. Res. 36, 337-
339.
11) Tadros, W., Larrman, J.J. (1976) Sarcocystis and
related coccidian parasites : A brief general reviw
together with a discussion on some biological
aspects of their life cycles and a new proposal for
their classification. Acta Leiden. 44, 1-107.
12) Tadros, W., Larrman, J.J. (1982) Current concepts
on the biology,evolution and taxonomy of tissue
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Parasitology. vol. 20. Academic Press, London. 293-
468 pp.
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30 動物の原虫病 第28巻 第1号(2013)
豚および野生イノシシにおける Sαrcocystis感染
斉藤守弘・萩原晶代
埼玉県食肉衛生検査センター
(2012. 7. 9受付)
要旨
2010年11月から 2011年3月までに埼玉県でと殺された肥育豚および繁殖豚,それぞれ50頭について,
住肉胞子虫の感染状況を調べた.繁殖豚50頭中3頭(6%)に Sarcocystismiescherianaの感染がみら
れたが,肥育豚には観察されなかった 2010年11月から 2011年3月までに埼玉県で捕獲された野生
のイノシシ 48頭中 3頭(6.3%)に S.miescherianaの感染がみられた.S. miescherianaシストはシス
ト壁が厚く柵状構造を呈していた走査電顕では,シスト表面に長さ 4-5μmの柵状のvillarprotrusion
が観察された.S. miescheriana感染肉を犬に投与したところ 投与後9日目以降の糞便内にスポロシ
ストの排世が認められた.
動物の原虫病 Vol.28, No. 1 : 25-30, 2013
Key words : dogs, pigs, Sarcocystis, wild boars