Hymenolepiasis is infestation by one of two species of tapeworm: Hymenolepis nana or Hymenolepis diminuta.

Hymenolepis live in warm climates and are common in the southern U.S. The eggs of these worms are ingested by insects, and mature into a life form referred to as a "cysticercoid" in the insect.

Humans and other animals become infected when they intentionally or unintentionally eat material contaminated by insects. In an infected person, it is possible for the worm's entire life-cycle to be completed in the bowel, so infection can persist for years.

Hymenolepis nana infections are much more common than Hymenolepis diminuta infections in humans. These infections were previously common in the southeastern U.S., and have been described in crowded environments and individuals confined to institutions. However, the disease occurs throughout the world.

Symptoms occur only with heavy infections. Symptoms include:

• gastrointestinal discomfort
• diarrhea
• weakness
• poor appetite

Examination of the stool for eggs and parasites confirms the diagnosis.

Praziquantel as a single dose is the current treatment of choice for hymenolepiasis.

Expect full recovery following treatment.

• abdominal discomfort
• dehydration from prolonged diarrhea

Call your health care provider if chronic diarrhea or abdominal cramping are present.

Good hygiene, public health and sanitation programs, and elimination of rats help prevent the spread of hymenolepiasis.