Diphyllobothriasis is the infection caused by tapeworms of the genus Diphyllobothrium (commonly D. latum and D. nihonkaiense). Diphyllobothriasis mostly occurs in regions where raw fish is regularly consumed; those who consume raw fish are at risk of infection. The infection is often asymptomatic and usually presents only with mild symptoms, which may include gastrointestinal complaints, weight loss, and fatigue. Rarely, vitamin B12 deficiency (possibly leading to anaemia) and gastrointestinal obstructions may occur. Infection may be long-lasting in absence of treatment. Diphyllobothriasis is generally diagnosed by looking for eggs or tapeworm segments in passed stool. Treatment with antiparasitic medications is straightforward, effective, and safe. Signs and symptoms
Most infections (~80%) are asymptomatic. Infections may be long-lasting, persisting for many years or decades (up to 25 years) if untreated. Symptoms (when present) are generally mild. Manifestations may include abdominal pain and discomfort, diarrhea, vomiting, constipation, weight loss, and fatigue. Additional symptoms have been reported/described, including dyspepsia, abdominal distension (commonly as presenting complaint), headache, myalgia, and dizziness. Complications
While the infection is generally mild, complications may occur. Complications are predicated on parasite burden, and are generally related to vitamin B12 deficiency and related health conditions. Vitamin B12 deficiency and anaemia
Vitamin B12 deficiency with subsequent megaloblastic anaemia (which is indistinguishable from pernicious anaemia) may occur in some instances of the disease. Anaemia may in turn result in subacute combined degeneration of the spinal cord and cognitive decline.D.
In Kyoto, it is estimated that the average annual incidence in the past 20 years was 0.32/100,000, and that in 2008 was 1.0 case per 100,000 population, suggesting that D. nihonkaiense infection is equally as prevalent in Japan as D. latum is in some European countries. United States
The disease is rare in the United States. History
The fish tapeworm has a long documented history of infecting people who regularly consume fish and especially those whose customs include the consumption of raw or undercooked fish. In the 1970s, most of the known cases of diphyllobothriasis came from Europe (5 million cases), and Asia (4 million cases) with fewer cases coming from North America and South America, and no reliable data on cases from Africa or Australia. Despite the relatively small number of cases seen today in South America, some of the earliest archeological evidence of diphyllobothriasis comes from sites in South America. Evidence of Diphyllobothrium spp. has been found in 4,000- to 10,000-year-old human remains on the western coast of South America. There is no clear point in time when Diphyllobothrium latum and related species were “discovered” in humans, but it is clear that diphyllobothriasis has been endemic in human populations for a very long time. Due to the changing dietary habits in many parts of the world, autochthonous, or locally acquired, cases of diphyllobothriasis have recently been documented in previously non-endemic areas, such as Brazil.