1. Identification of and surveillance for Syphacia pinworms in a
colony of Syrian hamsters (Mesocricetus auratus)
David K. Chu1*, Ramon A. Carreno2, Kristen M. Davis1, Sergio A. Koba1, Claude M. Nagamine1
Dept of Comparative Medicine, Stanford University1; Dept of Zoology, Ohio Wesleyan University2
Abstract Introduction Methods & Materials (continue) Results (continue) Discussion
An investigator studying the biology and
genetics of Sex-linked yellow (an X-linked gene
that determines coat color) acquired a stock of
hamsters from a private source. Pinworm ova
of an unidentified species were discovered
during health screening. These hamsters were
quarantined to guard our laboratory mice and
rats in case the helminthiasis was due to S.
obvelata or S. muris, which were reported to
infect Syrian hamsters. Primary goal of this
study was to identify pinworm species that was
infecting this hamster colony. Secondary goal
was to determine if this pinworm may infect the
mouse via dirty bedding transfer, a typical
means to survey for murine disease agents.
Answers to these questions may guide
laboratory managers and veterinarians on how
to assess the risks of infected hamsters to the
laboratory mouse. This study was Stanford
IACUC approved.
Host Specificity and Surveillance
➢ Transfer one teaspoon of dirty bedding with
feces from pinworm-infected hamsters to
three different sentinel cages weekly.
➢ Sentinel composition:
• Two Hsdhan:AURA female hamsters
• Three AG129 (129.Ifnar1tm1Agt,
Ifngr1tm1Agt) female mice
• Five AG B6 (C57BL/6J.129 Ifnar1tm1Agt,
Ifngr1tm1Agt) female mice
➢ Once per week for 5 weeks (beginning at 7
days post first dirty bedding transfer) we
conducted perineal cellophane tape tests
followed by perineal swabs from sentinels.
➢ Cellophane tapes were mounted on glass
microscope slides for microscopy.
➢ Swab samples obtained using Charles River
Labs (CRL) “pink sticky” swabs were sent
to CRL for PCR.
It may be necessary in a multi-species facility
to co-house different rodent species free from
adventitious infections. Goals of this study
were to identify pinworms found in a closed
golden hamster colony and to assess if a dirty
bedding surveillance program can detect
presence of this pinworm. For identification,
we retrieved worms from the cecum of
euthanized hamsters and fixed some either in
5% formalin for morphologic analysis or
90% ethanol for DNA sequencing. For
surveillance, we transferred one teaspoon of
dirty bedding with feces from pinworm-
infected hamsters to three sentinel cages
weekly. Sentinels were two female
Hsdhan:AURA hamsters and three female
129.Ifnar1tm1Agt, Ifngr1tm1Agt and five
C57BL/6.129 Ifnar1tm1Agt, Ifngr1tm1Agt mice,
immunodeficient strains with a double
knockout for Type I and II interferon
receptors. We conducted weekly perineal
cellophane tape tests plus we sent perineal
swab samples to a commercial lab for PCR.
Morphologically, the worms are consistent
with Syphacia mesocriceti. However, worm
dimensions are larger overall than in
previously published descriptions. 1000 bases
of the 28S rDNA locus were sequenced from
four worms and all four were identical. A
BLAST search revealed that the closest
match to the sequences is S. agraria at 86%
identity, followed by S. ohtaorum and S.
obvelata. No evidence of pinworms was
detected by tape tests or perineal swab PCR
at 1 and 2 weeks post bedding transfer. Ova
were observed on hamster cellophane tapes in
weeks 3, 4, and 5 while no ova were seen in
any of the mouse cellophane tapes. Hamster
swab PCR was positive for generic pinworm
in week 3 and mouse swab PCR was
equivocal in week 5. Our data suggest this
hamster colony is infected with S.
mesocriceti and that this pinworm is non-
transferable to the immunodeficient mouse
strains tested by dirty bedding.
*dchu98@stanford.edu
➢ GenBank BLAST search of 1000 bases of the
28S rDNA revealed that S. mesocricti 28S
rDNA sequences were not in GenBank.
 The closest match to the sequences is S.
agraria at 86% identity, followed by S.
ohtaorum and S. obvelata.
➢ Scan this poster’s QR code for BLAST results
and additional worm micrographs.
Figure 2. Male worm with characteristic spicule (arrow) which
facilitates sperm transfer. Syphacia demonstrates sexual
dimorphism in which male pinworms are much smaller than
females. This male measured 855 μm in length.
Figure 1. Anterior of a cleared, mature female worm. More
female worms were identified than males in our collection by a
15:2 ratio.
References
1. Dick TA, Quentin JC, Freeman RS. 1973.
Redescription Syphacia Mesocriceti (Nematoda:
Oxyuroidea) parasite of the golden hamster. J
Parasitol. 59(2):256-259.
2. Hasegawa H, Sato H, Iwakiri E, Ikeda Y, Une Y.
2008. Helminth collected from imported pet murids,
with special reference to concomitant infection of the
golden hamster with three pinworm species of the
genus Syphacia (Nematoda: Oxyuridae). J Parasitol.
94(3):752-754.
3. Okamoto M, Urushima H, Hasegawa H. 2009.
Phylogenetic relationships of rodent pinworms
(genus Syphacia) in Japan inferred from 28S rDNA
sequences. Parasitol Int. 58:330-333.
4. Pinto RM, Goncalves L, Gomes DC, Noronha D.
2001. Helminth fauna of golden hamster
Mesocricetus auratus in Brazil. Contemp Top Lab
Anim Sci. 40(2):21-26.
P196
Naturally Infected Host Animals
Closed colony of 5 to 8 month old mixed sex
Syrian hamsters (private source, Fresno, CA)
free from LCMV, PVM, Sendai virus,
Reovirus, SV5, E. cuniculi, C. piliforme,
external and other internal parasites housed in
hardwood bedded (Teklad), filter top cages
with feed (Teklad 2018) and RO filtered water.
Parasite Characterization
➢ Retrieve worms from intestinal trace of CO2
euthanized hamsters.
➢ Fix worms in 5% formalin for morphologic
analysis or 90% ethanol for DNA
sequencing.
➢ Worms were cleared with lactic acid and
viewed by light microscopy.
➢ Measure physical characteristics on 15
females and two males: Body length and
max width, cephalic vesicle length and
width, nerve ring width, excretory pore
width, vulva distance from anterior,
esophagus length, esophageal bulb length
and width, uterine corpus length and width,
tail length, ova length and width.
➢ Sequence 1000 bases of 28S rDNA locus.
➢ Survey GenBank for matching sequences
using BLAST.
Methods & Materials Results
Table 1. Female worm morphometric measurements with
reference values. All units are expressed as microns (μm).
Table 2. Perineal cellophane tape tests and fecal PCR results.
We consistently observed ova on hamster tapes since week 3.
Hamster feces was PCR positive on Pinworm Screen PCR
(but negative for Aspiculuris, S. obvelata, S. muris (CRL).
Pooled mouse feces yielded equivocal PCR results on week 5.
➢ This was a mono-infection by S. mesocriceti.
➢ Although S. mesocriceti was reported to
infect small intestine4, we found all of our
worms in the large intestine.
➢ Female morphology is slightly larger than
expected but overall is quite consistent with
what has been previously reported (Table 1).
➢ We encountered a BLAST search zero match
for S. mesocriceti because this pinworm
species is not in GenBank. An effort will be
made to deposit this species sequence into
GenBank.
➢ The 86% 28S rDNA S. agaraia match is
highly dissimilar for a relatively conserved
locus and that most of the 28S should be
identical or almost identical. Additionally,
S. agaraia is known to infect Large Japanese
field mouse3 and not likely to be pinworm
species in our colony of Syrian hamster.
However, polyinfection can occur2 and
should not be ruled out.
➢ Despite the fact that sentinel mice do not
express Type I and II interferon receptors
(increases their susceptibility to parasite
infection. Table 2 suggests that S.
mesocriceti is host specific or the risk of
fomite transmission to mice is low.
➢ Sentinel hamster tape tests and PCR don’t
correlate and may be explained by 1) Tapes
removed too much pinworm matter leaving
insufficient DNA for PCR 2) Positive tapes
in wks 4 and 5 were residuals from wk 3 or
3) Primers sensitivity was too low.
➢ Equivocal mouse fecal PCR result likely due
to contamination during sample acquisition.
Female
Characteristics Mean
Standard
Deviation
Reference
1
Reference
4
Body Length n=14 7261 742 5000 - 6900 3200 - 5200
Body Max Width
n=15 262 28 149 - 165 150 - 180
Cephalic Vesicle
Length n=14 173 30 - -
Cephalic Vesicle
Width n=14 143 16 - -
Nerve Ring (from
anterior) n=8 176 31 125 - 145 125 - 140
Excretory Pore (from
anterior) n=13 575 108 530 - 650 490 - 560
Vulva Distance from
Anterior n=11 926 170 810 - 890 700 - 830
Esophageal Length
n=15 414 30 - 280 - 385
Uterine Corpus
Length n=11 296 15 - -
Uterine Corpus
Width n=12 53 7 - -
Esophogeal Bulb
Length n=10 119 8 92 - 107 -
Esophogeal Bulb
Width n=15 98 9 77 - 88 -
Tail Length n=13 973 70 - -
Ova Length n= 40 128 4 115 - 118 130 - 140
Ova Width n= 40 33 3 31 - 46 40 - 50
 Worms were visualized in cecum; some in
colon; none in small intestine.