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FAQ ON DIPHYLLOBOTHRIASIS OR FISH TAPEWORM INFECTION

November 24, 2022

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FAQ ON DIPHYLLOBOTHRIASIS OR FISH TAPEWORM INFECTION

What is a fish tapeworm infection?

A fish tapeworm infection can occur when a person eats raw or undercooked fish that’s contaminated with the parasite Diphyllobothrium latum. The parasite is more commonly known as the fish tapeworm.

This type of tapeworm grows in hosts such as small organisms in the water and large mammals that eat raw fish. It’s passed through the feces of animals. A person becomes infected after ingesting improperly prepared freshwater fish that contain tapeworm cysts.

What are the symptoms?

Fish tapeworm infections rarely present noticeable symptoms. Tapeworms are most often discovered when people notice eggs or segments of the tapeworm in stool.

Symptoms could include:

diarrhea
fatigue
stomach cramps and pain
chronic hunger or lack of appetite
unintended weight loss
weakness

What causes a fish tapeworm infection?

A fish tapeworm infection occurs when a person eats undercooked or raw fish that’s contaminated with fish tapeworm larvae. The larvae then grow in the intestines. It takes between three to six weeks before they’re fully grown. An adult tapeworm can grow up to 30 feet longTrusted Source. It’s the largest parasite to affect humans.

The journal Emerging Infectious Diseasespublished a report that examined the spread of fish tapeworm infections in Brazil. Infections were linked to contaminated salmon farmed at aquaculture sites in Chile. The transportation of the contaminated fish from Chile brought the infection to Brazil, a country that hadn’t seen fish tapeworms before.

The report highlighted how fish farming can spread the infection from one area to another. The cases cited in the report all stemmed from people eating salmon sushi.

Who’s at risk for fish tapeworm infection?

This type of tapeworm parasite is most common in areas where people eat raw or undercooked fish from lakes and rivers. Such areas include:

Russia and other parts of Eastern Europe
North and South America
some Asian countries, including Japan

It may also be common in parts of Africa where freshwater fish are eaten.

In addition, fish tapeworms are seen in developing countries because of sanitation, sewer, and drinking water issues. Water contaminated with human or animal waste could very likely contain tapeworms. Fish tapeworm infection was regularly diagnosed in Scandinavia before improved sanitation methods were introduced.

How’s it diagnosed?

Your doctor may order a blood test to identify the presence of a parasite. However, this type of infection is most often diagnosed by examining a person’s stool for parasites, worm segments, and eggs.

How’s it treated?

Fish tapeworm infections can be treated with a single dose of medication without any lasting problems. There are two main treatments for tapeworm infections: praziquantel (Biltricide) and niclosamide (Niclocide).

Praziquantel. This drug is used to treat different kinds of worm infections. It causes severe spasms in the worm’s muscles so the worm can be passed through the stool.
Niclosamide. This drug is prescribed specifically for tapeworm infections and kills the worm on contact. The dead worm is later passed through the stool.

What complications are associated with fish tapeworm infection?

If left untreated, fish tapeworm infections can cause serious problems. These complications may include:

anemia, specifically pernicious anemia caused by vitamin B-12 deficiency
intestinal blockage
gallbladder disease

How can you prevent a fish tapeworm infection?

Fish tapeworm infections can be easily prevented. Use the following guidelines:

Cook fish at a temperature of 130°F (54.4°C) for five minutes.
Freeze fish below 14°F (-10.0°C).
Follow proper food safety handling, such as washing hands and avoid cross-contamination with raw fish and fruits and vegetables.
Avoid contact with any animal known to be infected with a tapeworm.
Exercise caution when eating and traveling in developing countries.

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

Fish Tapeworm Infection
Intestinal Diphyllobothriasis
Jewish Housewife’s Disease

What is Diphyllobothriasis? (Definition/Background Information)

Diphyllobothriasis is an infection usually caused by the tapeworm Diphyllobothrium latum. The condition may be caused by other Diphyllobothrium species too
These parasites are flatworms that infect the intestinal tract of human beings. Individuals are affected by eating raw or uncooked freshwater fish that contain tapeworm cysts. Some saltwater fishes may also harbor this organism
Diphyllobothriasis may cause abdominal pain, appetite loss, diarrhea or constipation, vomiting, nausea, and fatigue. The condition may be diagnosed by examining the stool samples
The treatment involves the administration of oral and intravenous medications. The prognosis is generally good with no significant long-term complications, if the condition is suitably treated

Who gets Diphyllobothriasis? (Age and Sex Distribution)

All individuals, having a regular habit of taking raw or undercooked fish, are likely to get Diphyllobothriasis. Individuals of all ages may be affected by the infection
Jewish women were once most commonly infected by the parasite, due to their tradition of tasting fish, before it was fully-cooked. For this reason, Diphyllobothriasis is also known as “Jewish Housewife’s Disease”
Otherwise, no specific ethnic or racial predilection is noted

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

The risk factors for Diphyllobothriasis include:

Consumption of raw or undercooked (usually) freshwater fish
Fishermen and their families, who primarily consume fish are higher prone to the condition
Housewives are at a high risk, when they taste undercooked fish, during its preparation
Eating certain regional cuisines, where raw/semi-cooked fish is served; like in certain Japanese, French, or Italian food preparations
People living in areas where eating freshwater fish (including dry-salted, smoked) is common, like in Eastern Europe, North and South Americas, some African, Asian, and Scandinavian countries

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones 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 Diphyllobothriasis? (Etiology)

Humans are infected by Diphyllobothriasis, when they eat raw or undercooked fish that contains fish tapeworm cysts (especially belonging to the tapeworm Diphyllobothrium latum)
When an individual consumes the infected fish, the tapeworm larva begins to grow in the intestine. In about 3-6 weeks’ time, it grows to become an adult worm
Eggs are formed in each segment of the worm, which is then passed out in the stool. Sometimes, the whole worm or parts of the worm may be seen in the stool

What are the Signs and Symptoms of Diphyllobothriasis?

The following signs and symptoms characterize a Diphyllobothriasis infection:

Abdominal pain
Loss of appetite, sudden weight loss
Diarrhea or constipation
Vomiting, nausea, and fatigue
Deficiency of vitamin B12
Anemia
Presence of worm eggs (or worm parts) in stool
In most of the human population, the infection remains asymptomatic

How is Diphyllobothriasis Diagnosed?

A diagnosis of Diphyllobothriasis may involve:

Physical evaluation and study of medical history
Examination of stool for the presence of eggs and parasites; tapeworm segments (proglottids) passed in the stool, is also examined for confirmation
Complete blood count to check for anemia

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 Diphyllobothriasis?

The possible complications that can arise from Diphyllobothriasis are:

Vitamin B12 deficiency leading to megaloblastic anemia (blood disorder characterized by anemia with larger than normal-sized red blood cells)
Intestinal obstruction in extreme infections

How is Diphyllobothriasis Treated?

The treatment measures for Diphyllobothriasis mainly involve:

Taking oral medications like praziquantel or niclosamide. The healthcare provider will choose the specific medications necessary, since some of the medications are not (US FDA) approved
Vitamin B12 injections are taken as supplements, in order to treat megaloblastic anemia

How can Diphyllobothriasis be Prevented?

The following preventive measures can be adopted to reduce the risk of Diphyllobothriasis:

Eating raw or undercooked (especially freshwater) fish must be avoided. Cooking fish to temperatures over 145 deg. F (63 deg. C) kills the parasitic organism
Wash hands properly after cleaning fish, before preparing food, and before eating
Freshwater fish may be stored frozen before preparation; freezing fish up to -4 deg. F (-20 deg. C) for 24 hours, helps kill the tapeworm eggs
Proper disposal of sewage (including fish wastes) can help bring down the risk of contracting Diphyllobothriasis
Proper hygiene must be adhered to at all times (by both children and adults) – wash hands with soap and water after defecation
Water contaminated or infected with feces (containing the parasite) must be avoided

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