Oxyuriasis (Pinworms)
medication regimens for eradicating pinworms from
persistent problem of well-managed animal colonies.
rodents: ivermectin or fenbendazole. Both methods
Pinworms that commonly infect laboratory colonies
have advantages and disadvantages for the
include Syphacia muris, S. obvelata, and Aspiculuris
researcher, animal and animal care staff.
Ivermectin is either applied topically to the
perineum of the affected animals or administered in
Transmission: The pinworm life cycle is direct. Adult
the drinking water. Although ivermectin is not
worms inhabit the colon and cecum. Eggs are shed in
expensive, this treatment regiment is extremely labor
the feces or deposited on the perianal region of the
intensive. All animals need to be handled daily for 7 to
rodent. The eggs are very light and aerosolize easily,
10 days if it is being applied topically. MI bottles need
facilitating infection. Embryonated eggs are ingested,
to be changed daily for 7 to 10 days if it is being
administered in the water. Ivermectin can interfere
It has been shown that embryonated eggs can
with neurological function and is generally not
survive at room temperature for extended periods of
recommended in colonies doing behavioral research.
Fenbendazole is administered orally through
specially prepared rodent chows. These diets are
Clinical Signs: Clinical signs are related to the
expensive when compared to normal rodent diets.
parasite burden in a particular animal. In general,
Typically, the rodents are fed the diet containing
weanling animals and males tend to be more heavily
fenbendazole for at least four 7 to 10-thy treatment
periods with intervening 7 to 10-day periods of
The infection is usually subclinical, with no
feeding with non-medicated chow. Alternatively, the
apparent clinical signs. However, infected mice can
diet may be given for 6 weeks straight. Fenbendazole
develop rectal prolapses, intussusceptions, fecal
may interfere with liver function, making it an
impactions, poor weight gain, rough hair coats, bloody
undesirable choice for studies that require normal
feces, and perianal irritation. The disease is usually
Regardless of medication selected, increased
sanitation should be practiced. All caging, equipment,
Diagnosis: Diagnosis is usually based on identification
and room surfaces should be disinfected as directed
of the parasite eggs in a fecal flotation (Aspiculuris sp.)
by the veterinarian. Generally, compounds such as
or by examining a tape test (Syphacia sp.). Adult
chlorine disinfectants and quatemary ammonia
worms can also be seen with direct examination of
compounds are recommended. Autoclaving and
the cecum and colon with a dissecting microscope.
A recent study (Huerkamp, 2000) suggests that if
Effects on Research: Pinworm infections have
five fenbendazole treatment periods are used (for a
resulted in significantly higher antibody production to
total of 9 weeks of treatment) to treat Syphacia,
sheep red blood cells, reduced occurrence of
intensive sanitation may not be required for colonies
adjuvant-induced arthritis, and impaired intestinal
of rats. This is promising information, but may not be
electrolyte transport. As athymic nude mice are more
applicable to Aspiculuris sp. or infections in mice.
susceptible to these infections, increased morbidity
Further information is required before this can be
can interfere with research using infected mice.
uniformly recommended, but this method may be
replacement stocks from sources that are known to
be free of disease. Personnel working with infected
Baker, DG. 1998. “Natural Pathogens of Laboratory Mice, Rats,
animals should not enter rooms that contain naïve
and Rabbits and Their Effects on Research.” Clinical Iviicrobiology
All animals should be placed in microisolator
caging environments that are handled with the aid of
Huerkamp, MJ etal. 2000. “Fenbendazole treatment without
a laminar flow hood using sterile techniques during
environmental decontamination eradicates Syphacia muris from all
handling and observation of the animals.
rats in a large, complex research institution.” Contemporary Topics.
Eradication: Currently there are two widely accepted
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