Hymenolepis diminuta
المؤلف:
Patricia M. Tille, PhD, MLS(ASCP)
المصدر:
Bailey & Scotts Diagnostic Microbiology
الجزء والصفحة:
13th Edition , p684
2025-11-03
62
GENERAL CHARACTERISTICS
Hymenolepis diminuta, the rat tapeworm, is larger than H. nana and can measure 20 to 60 cm in length. Outbreaks of human infection are rarely seen.
EPIDEMIOLOGY
H. diminuta is a tapeworm infrequently seen in humans and frequently found in rodents including rats and mice. Rats are typically the natural reservoir. H. diminuta can infect humans following contamination of grains and flours with rodent feces.
PATHOGENESIS AND SPECTRUM OF DISEASE
The life cycle of H. diminuta involves insects, similar to the life cycle of H. nana. H. diminuta rarely infects humans, but may do so if a human accidentally ingests an arthropod infected with cysticercoids. Multiple adult worms may mature in the human intestine. Infections are usually tolerated well by the host because of the small size of the organism. Symptoms may include diarrhea, anorexia, nausea, headache, and dizziness. The infection is more common in children, causing mild diarrhea, remittent fever, and abdominal pain.
LABORATORY DIAGNOSIS
Proglottids are rarely seen in the stool; diagnosis is made by the identification of eggs. The eggs (70 to 85 µm by 60 to 80 µm) are large, ovoid, yellowish, and moderately thick-shelled. The eggs contain a six-hooked oncosphere with the absence of polar filaments in the space between the oncosphere and the eggshell (see Figure 1). The eggs are clearly differentiated from H. nana because of the absence of polar filaments.
Fig1. A, Taenia spp. egg. B, Diphyllobothrium latum egg. C, Hymenolepis diminuta egg. D, Hymenolepis nana egg. E, Dipylidium caninum egg packet.
ANTIPARASITIC SUSCEPTIBILITY TESTING AND THERAPY
H. diminuta is readily treated with praziquantel, although the disease is self-limiting and treatment is often not necessary.
PREVENTION
Prevention is attained primarily by controlling the mice and rat populations along with good hygiene and sanitation.
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