II. Cestodes
III. Pinworms
IV. Mange Mites
Spironucleus muris (left photo), Giardia sp., Tritrichomonas
sp., and
Entamoeba
sp. (right photo) are protozoa which commonly
inhabit the small and large intestine without causing clinical signs.
When the luminal contents become more fluid, as in the case of bacterial
enteritis, these protozoa take advantage of the opportunity to replicate,
and frequently aggravate the inflamed intestinal tract.
A. Etiology: Rodentolepis nana (dwarf tapeworm) and
Hymenolepis
diminuta infect hamsters with a moderate rate of incidence.
Rodentolepis
nana adults range from 25 to 40 mm long and less than 1 mm wide and
have an armed rostellum (see photo). Hymenolepis diminuta
adults
range from 20 to 60 mm in length and 3 to 4 mm wide with no hooks on the
scolex. 
B. Transmission: Rodentolepis nana and Hymenolepis diminuta can be transmitted indirectly with cockroaches, beetles, or fleas as intermediate hosts. Rodentolepis nana can also be transmitted by direct ingestion of hexacanth ova and autoinfection in which the entire life cycle occurs in the small intestine without ingestion of ova (direct life cycle is 14 to 16 days).
C. Clinical Signs: Usually there are no external signs of infection. Impactions have been reported with heavy infections resulting in intestinal obstruction.
D. Diagnosis: Diagnosis can be made by fecal flotation
and examination for hexacanth ova (see photo), direct examination of intestines
with a dissecting microscope, or histopathological examination of the small
intestine. 
E. Treatment: Niclosomide (Yomesan) at 10 mg/100 gm body weight given in a treatment at 7 day intervals is effective but not currently available in the U.S. Thiabendazole at 0.33% crushed and mixed in pulverized feed for 7 to 14 days have been effective. Praziquantel at 5.1 -11.4 mg/kg IM, SQ or PO (repeat in 10 days) can be used in both hamsters and gerbils.
F. Control: Cockroaches should be eliminated and infected animals killed or treated.
Public Health Significance: People become infected with R. nana from contact with the ova; since autoinfection can occur, a heavy parasite load may quickly develop.
A. Etiology: Syphacia mesocricetus is the hamster
pinworm (see photo). Syphacia obvelata and Syphacia muris
are also capable of infecting hamsters. Prevalence of a pinworm infection
is low, however the incidence of parasitism within individual colonies
may be high.
B. Transmission: Syphacia sp. deposit eggs in the perianal region. Transmission of infection occurs via ova ingestion. The eggs are very light and have been shown to aerosolize, resulting in widespread exposure.
C. Clinical signs: No signs are usually seen. Heavy parasite loads may lead to rectal prolapse or perianal irritation.
D. Gross Pathology: Pinworms are easily recognized as white hair-like nematodes in the cecum.
E. Diagnosis: Direct exam of cecal contents to identify
adult worms, and fecal flotation, and perianal tape test for ova (see photo)
are routinely used diagnostic methods. 
F. Treatment: If treatment is desired, two doses of piperazine (10 mg/ml water) for 7 days followed by 5 days without treatment is effective. Thiabendazole at 0.1% in the feed for 3 to 4 weeks is also effective. To prevent reinfection the environment should be thoroughly cleaned to remove ova. Although ivermectin has been successfully used to treat pinworm-infected mice and rats at a dose of 0.2 to 0.4 mg/kg, similar treatments of hamsters should be effective, but have not been reported.
G. Control: Rigid sanitary procedures, and use of filter hoods should be employed to prevent aerosol transmission. Regular ova examinations with treatment may control the parasitism.
A. Etiology: Demodex criceti and Demodex aurati are mange mites of hamsters. High incidence of infestation occurs without clinical signs. The mites are generally found together. Demodex criceti is considered non-pathogenic and is found in the epidermis. Demodex aurati, the more pathogenic mite, is found in the pilosebaceous component of the skin.
B. Transmission: Demodex infestations are thought to be spread by direct contact.
C. Clinical Signs: Clinical signs can range from none to
alopecia, dry, scaly, scabby dermatitis, and rough hair coat. Alopecia
generally occurs over the rump and back. Predisposing factors are
considered necessary for the development of clinical signs including malnutrition,
concurrent systemic disease, and age. 
D. Diagnosis: Skin scrapings of alopecia skin will reveal
mites. Demodex criceti has a shorter body length and is scraped
from epidermal pits (A.). Demodex aurati is longer that Demodex
criceti, and is squeezed from the hair follicles (B.).
F. Treatment: Lime and sulfur dips have been used successfully. Topical therapy with Mitaban or systemic therapy with ivermectin has also been effective.
G. Control: Clinical signs of demodiosis in hamsters are generally
secondary to immunosuppression. Prognosis for control will depend
on the underlying etiology. Adequate nutrition and good husbandry
decrease the incidence of clinical signs in infected hamsters.
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