What are the other Names for this Condition? (Also known as/Synonyms)

• Dwarf Tapeworm Infection
• Tapeworm Infection by H. Diminuta
• Tapeworm Infection by H. Nana

What is Hymenolepiasis? (Definition/Background Information)

• Hymenolepiasis is an intestinal infection by one of two specific types of the following Hymenolepis species of tapeworm parasite:
  • The Hymenolepis nana (commonly known as the dwarf tapeworm)
  • And, the Hymenolepis diminuta (commonly known as the rat tapeworm)
• Like most tapeworms, this species of tapeworm is incapable of digesting nutrients on its own. Thus, it depends on the host to digest the nutrients, so that it can absorb them while staying attached to the intestinal wall of the host/individual
• Hymenolepiasis infection commonly presents with diarrhea and abdominal pain in the affected individuals. If left untreated, it can result in complications that include severe abdominal symptoms and dehydration
• A healthcare provider typically diagnoses Hymenolepiasis upon examination of the stool for parasitic material, and may prescribe anthelmintic medication towards treating Hymenolepiasis
• The prognosis of Hymenolepiasis is generally good, following prescribed treatment. Individuals are known to make a full recovery

Who gets Hymenolepiasis? (Age and Sex Distribution)

• Infection by Hymenolepis nana is among the most common of tapeworm infections worldwide
• Individuals of all ages, races, ethnic groups, and both genders are capable of contracting Hymenolepiasis 
• There is a higher incidence of infection in the temperate zones, especially among children and incarcerated individuals
• The infection is also frequently reported in many developed and undeveloped regions of the world; thus, a worldwide geographic distribution pattern is observed

What are the Risk Factors for Hymenolepiasis? (Predisposing Factors)

The risk factors for the development of Hymenolepiasis (in the endemic regions) include:

• A major risk factor for developing Hymenolepiasis is the frequent ingestion of contaminated or spoiled food. Ingestion of foods that have been infected with eggs of the tapeworm is the most common mode of infection
• Childhood: Children are generally more prone to infections
• Prisoners

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Hymenolepiasis? (Etiology)

Hymenolepiasis is caused by an infestation of the intestine by a species of tapeworm, called Hymenolepis nana or Hymenolepis diminuta, which attach to the walls of the intestine and ingest food previously digested by its human host.

• Hymenolepiasis commonly spreads through the ingestion of feces (containing the parasitic eggs) of other infected organisms, often referred to as an intermediate host
• Intermediate hosts of Hymenolepis nana/diminuta are most commonly insects that have contaminated household food items. They have also been known to infest rats, before infecting a human host. The intermediate hosts dispel eggs of the parasitic tapeworm, either upon defecation or following its death
• These eggs are unintentionally ingested, when the eggs infect a household food source (often contaminated grains). After the eggs have been ingested, they hatch after entering the small intestines, where they eventually grow into adult worms
• The Hymenolepis adult worms continue to reside in the intestines and consume the food digested by their human host. This results in inflammation of the intestine, that is brought about by an immune reaction of the body to a foreign object attaching itself to the intestine

It should be noted that the Hymenolepis parasite does not require an intermediate organism to infect humans. Many cases of Hymenolepiasis have shown the tapeworm settling indefinitely in insects, rats, or humans.

What are the Signs and Symptoms of Hymenolepiasis?

The signs and symptoms of Hymenolepiasis may vary in severity, depending on the magnitude and duration of infection and can include a combination of the following: 

• Diarrhea
• Abdominal pain
• Headaches and weakness
• Poor appetite
• Itchy anus
• Dehydration (due to long-term diarrhea)

How is Hymenolepiasis Diagnosed?

The diagnosis of Hymenolepiasis is made by the following tests and exams:

• A complete physical examination and a thorough assessment of symptoms
• An evaluation of the affected individual’s medical history
• Stool examination for the presence of eggs and tapeworms. Examination of the stool is often done under microscope to confirm the morphology of Hymenolepis nana/diminuta

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis

What are the possible Complications of Hymenolepiasis?

The potential complications of Hymenolepiasis may include the following:

• Dehydration from long-term diarrhea (more common in children), which may cause mild to severe weakness and worsening of overall health
• Increased abdominal discomfort that often results from leaving an infection untreated, for an extended period of time

How is Hymenolepiasis Treated?

The treatment of Hymenolepiasis may include the following:

• Prescription of anthelmintics, which are a class of medication that kill parasitic tapeworms (without interfering with the normal bodily functions), by either paralyzing or starving the tapeworms until they die. This causes them to detach from the tissues and be excreted
• Electrolyte therapy for rehydration, to treat secondary symptoms in the affected individuals, particularly children

How can Hymenolepiasis be Prevented?

Prevention of Hymenolepiasis is possible by keeping one’s household and surroundings clean. Apart from this, the following may be considered:

• Proper storage of grains, flour, cereal, and wheat based foods that may be contaminated by the Hymenolepis parasites 
• Maintaining good general and personal hygiene
• Extermination of rats to prevent spread of diseases such as Hymenolepiasis. This can greatly reduce the incidence of infestation

What is the Prognosis of Hymenolepiasis? (Outcomes/Resolutions)

• The prognosis of Hymenolepiasis is often good with proper administration of medication in a timely manner. Anthelmintic drugs are highly-effective in completely removing Hymenolepis from the body (intestines)
• Failure to seek appropriate medical care can lead to the exacerbation of symptoms and additional complications that may be severe in children. Untreated infections have been known to persist for several years

Additional and Relevant Useful Information for Hymenolepiasis:

• Infection by Hymenolepis nana is far more common in humans than infection by Hymenolepis diminuta, although many known cases of infection by either parasite are known
• There are 400 known species of Hymenolepis, all of which infect higher order vertebrates
• Morphologically, the Hymenolepis species of tapeworm is the smallest tapeworm in the cestode family. They can grow up to 40 mm as adults and have small, oval-shaped eggs with 6 distinct hooks inside their shells