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A fish tapeworm infection can occur when a person eats raw or undercooked fish that is 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.
According to the National Center for Biotechnology Information (NCBI), this type of tapeworm parasite is most common in areas where people eat raw or undercooked fish from lakes and rivers. Locations include:
This may also be common in parts of Africa where freshwater fish are eaten.
A fish tapeworm infection occurs when a person eats undercooked or raw fish that is contaminated with fish tapeworm larvae, which then grow in the intestines. It takes between three to six weeks before the larvae are fully grown. An adult tapeworm can grow up to 30 feet long. It’s the largest parasite to affect humans.
The journal Emerging Infectious Diseases published 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.
Fish tapeworms are more common 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 infections rarely present noticeable symptoms. Tapeworms are most often discovered when people notice eggs or segments of the tapeworm in stool.
Symptoms could include:
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.
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.
According to the NCBI, treatment is important because fish tapeworm infections can cause serious problems, such as anemia or intestinal blockage.
Fish tapeworm infections can be easily prevented using the following guidelines:
Written by: Brian Krans
Medically reviewed on: Jul 17, 2015: Steven Kim, MD
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