Diphyllobothriasis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Furqan M M. M.B.B.S[2], Kalsang Dolma, M.B.B.S.[3]
Overview
Diphyllobothriasis is an infection commonly caused by Diphyllobothrium latum. Eggs of Diphyllobothrium that date back to 4000 BC have been found in France and Germany. In 1592 AD, T. Dunus gave the first recognizable description of the disease and the life cycle was fully elucidated at the end of the 19th century. D. latum has an aquatic life cycle and it is usually transmitted to humans by ingestion of the affected aquatic intermediate host (freshwater or marine fish). It usually causes abdominal pain, diarrhea, and numbness of extremities. Diphyllobothriasis is common in areas with lakes and rivers where humans consume raw or undercooked freshwater fish particularly Japan, Scandinavia, Siberia, and sporadic cases in North and South America. A common risk factor in the development of diphyllobothriasis is consumption of raw or poorly cooked fish meat.The symptoms of diphyllobothriasis usually develop after eating undercooked or raw infected fish meat and start with symptoms such as abdominal pain, diarrhea, nausea, vomiting, and tiredness. If left untreated, patients with diphyllobothriasis may progress to develop complications such as megaloblastic anemia, cholecystitis/cholangitis, and intestinal obstruction. The prognosis of diphyllobothriasis is generally good. Patients with diphyllobothriasis are usually asymptomatic but may be irritated. Physical examination of patients with diphyllobothriasis is usually remarkable for abdominal tenderness, pale conjunctiva, pale skin, and decreased vibration and position senses. The diagnosis is made by identifying eggs of the parasite in stool. Blood tests may show megaloblastic anemia, eosinophilia, and a low vitamin B12 level. Diphyllobothriasis is medically treated with a single dose of praziquantel. The transmission of diphyllobothriasis can be prevented by avoiding undercooked or raw fish meat.
Historical Perspective
Eggs of Diphyllobothrium that date back to 4000 BC have been found in France and Germany. In 1592 AD, T. Dunus gave the first recognizable description of the disease and the life cycle was fully elucidated at the end of the 19th century.
Classification
There is no known classification for diphyllobothriasis but it may be classified on the basis of the organisms causing it.
Pathophysiology
Diphyllobothriasis is a disease caused by Diphyllobothrium latum. D. latum has an aquatic life cycle and is usually transmitted to the humans by ingestion of the affected aquatic intermediate host (freshwater or marine fish). D. latum decreases the intestinal absorption of vitamin B12, resulting in megaloblastic anemia in humans.
Causes
Diphyllobothrium is a genus of tapeworm that can cause Diphyllobothriasis in humans through consumption of raw or under cooked fish. The principal species causing diphyllobothriosis is Diphyllobothrium latum, known as the broad or fish tapeworm, or broad fish tapeworm. D. latum is a pseudophyllidea cestode that infects fish and mammals. D. latum is native to Scandinavia, western Russia, and the Baltics, though it is now also present in North America, especially the Pacific Northwest. Other members of the genus Diphyllobothrium include Diphyllobothrium dendriticum (the salmon tapeworm), which has a much larger range (the whole northern hemisphere), D. pacificum, D. cordatum, D. ursi, D. lanceolatum, D. dalliae, and D. yonagoensis, all of which infect humans only infrequently. In Japan, the most common species causing human infection is D. nihonkaiense, which was only identified as a separate species from D. latum in 1989.[1]
Differentiating (Disease name) from other Conditions
Diphyllobothriasis must be differentiated from tapeworm infections like taeniasis, hymenolepiasis, and schistosomiasis.
Epidemiology and Demographics
Diphyllobothriasis occurs in areas with lakes and rivers where humans consume raw or under cooked freshwater fish. It is particularly common in Japan, Scandinavia, Siberia, with sporadic cases in North and South America.
Risk Factors
A common risk factor in the development of diphyllobothriasis is consumption of raw or poorly cooked fish meat.
Screening
There is insufficient evidence to recommend routine screening for diphyllobothriasis.
Natural History, Complications and Prognosis
The symptoms of diphyllobothriasis usually develop after eating undercooked or raw infected fish meat and start with symptoms such as abdominal pain, diarrhea, nausea, vomiting, and tiredness. If left untreated, patients with diphyllobothriasis may progress to develop complications such as megaloblastic anemia, cholecystitis/cholangitis, and intestinal obstruction. The prognosis of diphyllobothriasis is generally good.
Diagnosis
History and Symptoms
The history of patients with diphyllobothriasis is significant for eating raw or poorly cooked fish meat. The symptoms of diphyllobothriasis may include abdominal pain, diarrhea, nausea, vomiting, and, less commonly, numbness of toes and fingers.
Physical Examination
Patients with diphyllobothriasis are usually asymptomatic but may be irritated. Physical examination of patients with diphyllobothriasis is usually remarkable for abdominal tenderness, pale conjunctiva, pale skin, and decreased vibration and position senses.
Laboratory Findings
Diphyllobothriasis can be diagnosed with the morphological identification of Diphyllobothrium eggs and adults in the stool exam. Molecular diagnosis can also be made with the PCR. Blood tests may show megaloblastic anemia, eosinophilia, and a low vitamin B12 level.
Chest X Ray
There are no X-ray findings associated with diphyllobothriasis.
CT
There are no CT findings associated with diphyllobothriasis.
MRI
There are no MRI findings associated with diphyllobothriasis.
Echocardiography or Ultrasound
There are no echocardiography or ultrasound findings associated with diphyllobothriasis.
Other Imaging Findings
There are no other imaging findings associated with diphyllobothriasis.
Other diagnostic findings
Colonoscopy can reveal Diphyllobothrium latum, usually located in the terminal ileum and extending to the sigmoid colon.
Treatment
Medical Therapy
Drugs used for diphyllobothriasis include praziquantel and niclosamide.
Surgery
Surgical intervention is not recommended for the management of diphyllobothriasis.
Primary Prevention
Effective measures for the primary prevention of diphyllobothriasis include avoiding/limiting consumption of raw fish and proper cooking and storing of fish meat.
Secondary Prevention
The secondary prevention strategies for diphyllobothriasis are similar to its primary preventive measures.