Diphyllobothriasis is an intestinal disease resulting from broad tapeworms including Diphyllobothrium latum and Diphyllobothrium nihonkaiense, affecting people who consume raw fish containing plerocercoid larvae. Patients may present with gastrointestinal complaints or passing of worm segments in stool without significant diarrhea. 

D. latum can reach more than 20 meters in length and exists for more than ten years; in some cases, this can lead to vitamin B12 deficiency, but cases of it being severe are not numerous. Evidence of infestations with these tapeworms has been documented to have existed for thousands of years, and the first clinical descriptions date back to the 16th century. The disease was more common in freshwater areas of Europe till the beginning of the twentieth century.

By the year 1970, it is estimated that about 9 million people were infected and most of them were from the European and Asian continent. Even though the infection rate has declined in developing countries due to improved sewage systems, zoonotic infections are prevalent with other tapeworm species. High intake of raw seafood and better food supply chain has given rise to diphyllobothriasis lately across a wider area and different species. 

The two species of broad tapeworms, Diphyllobothrium latum and Diphyllobothrium nihonkaiense, have diffuse life cycles which were previously not well elucidated up to molecular biology. Morphologically, D. latum occurs in the lakes in Eurasia while D. nihonkaiense occurs in the North Pacific. It affects fish such as perch, pike, hake, and salmonids; adaptation to South Americans Salmonids can affect public health and economies. 

The global incidence of diphyllobothriasis was estimated to be 20 million in 2002; however, disease-specific prevalence is not well characterized due to low awareness, underreporting, and underdiagnosis. This disease is prevalent in Japan but can be found worldwide, though not in Africa or Australia, and regions where sushi or raw fish is usually consumed is prevalent. 

Sanitation improvements have eased the disease slightly in many areas, and D. latum is no longer considered endemic in regions such as the UK and the Netherlands. However, it also does not suggest that these improvements are equal for all regions, with only minimal reductions in some indigenous population. Diphyllobothriasis was previously classified as re-emerging because of increased occurrences in non-endemic areas due to travel, migration and consumption of raw fish. Transportation of fish and challenges in aquaculture also play a role in spreading the disease. 

Once a tapeworm has penetrated the intestine, it changes the concentration of neuromodulators not only in the intestine but also in the serum. These changes cause histological alterations of the morphophysiological features of the gastrointestinal tract, neuroendocrine functions, secretion and motility. The damage is done through the degranulation of mast cells and eosinophils and subsequent release of cytokines. 

Chronic or severe Infection with Diphyllobothriidae leads to a deficiency of vitamin B12 because the tapeworm deregulates the host’s intrinsic factor and absorbs vitamin B12 at a much faster rate than the human intestines. It is estimated that approximately 40 percent of subjects infected with D.latum have Vitamin B12 deficiency at the time of diagnosis, though only less than 2 percent of them experience clinical anemia. 

Diphyllobothriasis is an intestinal infection that arises from ingesting raw, undercooked fish or fish that were not previously frozen and contain tapeworm larvae. Diphyllobothrium latum and Diphyllobothrium nihonkaiense are mainly responsible for this type of infection, however in rare cases, other species of Diphyllobothrium and similar organisms can be involved in infecting an individual. 

Diphyllobothriasis is usually a benign illness, and the overall prognosis of this disease is generally favorable. Diphyllobothrium latum infection is not parasitic and most cases are rarely fatal. Failure to treat these patients will lead to distress and anxiety as the worm segments pass through them for a long time. Generally, the patients require only one dose of the medication, but some may need subsequent therapy if the initial course is not sufficient. 

In the rarest of cases, the infection can cause the severe form of anemia called megaloblastic anemia or intestinal blockage especially when the worm burden is high. However, macrocytic anemia and neurological complications have been reported, although they are very rare. Gastrointestinal obstruction is also rare but may manifest when there are many worms in the affected cases. 

Age Group 

Diphyllobothriasis can occur in any age group; however, adults get affected more often because of their eating habits. Children may also be affected, especially in the areas where they prepare and consume raw fish. 

Clinical assessment in diphyllobothriasis mainly revolves around evaluating signs and symptoms related to the gastrointestinal system. They include abdominal tenderness, which suggests that the patient feels uncomfortable or experiences pain because of the infection. There may be swelling of abdomen or bloating especially where the infestation is severe. In some instances, there may be a palpable mass if the patient has severe gastrointestinal obstruction. 

Dietary Habits: This is associated with the fresh, raw, or undercooked fish and fish which are prepared from unfrozen meats. The individuals who frequently consume raw fish products such as sushi, ceviche, and other similar dishes are more vulnerable. 

Geographic Factors: It has been more prevalent in areas with traditional raw fish consumption, which include part of Asia, Europe and South America. 

Sanitation: Hygiene and cleanliness are also known to play major roles in increasing the risk of the disease. 

Acute Symptoms: Some people can have either non-specific or very few clinical symptoms. If symptoms become apparent, they are mostly in form of abdominal discomfort, diarrhoea, and nausea. Tapeworm segments in the feces may be an indication of a tapeworm infestation. 

Chronic Symptoms: Long term complications include vitamin B12 deficiency, megaloblastic anaemia or gastrointestinal obstruction though they are comparatively rare. Some signs associated with low levels of vitamin B12 may be weakness, fatigue and neurological manifestations; however, these are uncommon. 

Antiparasitic Medication: 

• Praziquantel: It is the anti-parasitic drug of choice in the management of diphyllobothriasis. It is effective against several types of tapeworms and is used in the treatment of Diphyllobothrium latum infection. Usually, it only takes one dose to eliminate the infection and any discharge. 

Symptomatic Management: 

• Vitamin B12 Supplementation: In cases where the infection has resulted in low levels of vitamin B12, then the recommended doses may be used to correct anemia or neurological anomalies. It is given based on the degree of deficiency, which may be in doses and for periods. 
• Management of Complications: In some cases, complications like gastrointestinal obstruction will arise and correct management may need to be done. This may involve all forms of operations or any form of supportive intervention. 
• Follow-Up: Follow up is crucial to confirm the effectiveness of the therapeutic intervention and to screen for reinfection or complication. There may be also repeated examinations of the stool to make sure that there were no tapeworms. 
• Education: The patients should be instructed the precaution to take precautions to avoid reoccurrence, that include proper preparation of fish such as proper cooking or freezing and good personal hygiene practices. 

Infectious Disease

Dietary and Food Safety Practices: Consumers should avoid consuming raw or undercooked fish since heat treatments can destroy the tapeworms and prevent the infection. It is recommended that people should avoid eating raw fish, or they can cook fish to an internal temperature of at least 63°C (145°F) or freeze fish at a temperature of -20°C (-4°F) for at least 7 days as a way of avoiding this disease. By providing information on possible dangers connected to raw or undercooked fish eating, especially in places where this zoonosis is widespread, people’s infection is preventable. 

Hygiene and Sanitation: Consequently, common preventive measures like proper etiquette touching surfaces, washing of hands and handling foods can be encouraged to reduce cases of gastrointestinal infections. Awareness on proper manner and procedure in handling and preparing fish in food industries and homes is very important. This ranges from making sure that the surfaces are clean and the foods well handled. 

Nutritional Support: For the patients who got vitamin B12 deficiency because of the infection, they can change their diet and give special attention to take some vitamin B12 supplements. This is by taking foods that are rich in B12 or any products that are fortified with B12. 

Infectious Disease

Praziquantel: It is widely used for treatment of numerous parasitic infections and is chosen as the first-line drug for diphyllobothriasis. It functions by enhancing the membrane permeability in the target roundworms making it easier for calcium ions to flush out of the worms leading to rigid spasms and subsequently, paralysis. The tablets should be swallowed with liquid during meals, if it is kept in the mouth it will result to bitterness which can lead to vomiting. For diphyllobothriasis, the standard dose is a single dose of 25 mg/kg. While 10 mg/kg has proved adequate against D. pacificum, 25 mg/kg is used for D. latum and D. nihonkaiense. 

Niclosamide: It is an alternative treatment for infections caused by Diphyllobothrium species. It has some restrictions in some areas mainly because of availability. This drug targets the parasite by disrupting its mitochondrial oxidative phosphorylation and its ability to take up glucose. It has been used as the single oral dose of 2 grams for adult patients, and side effects from using amoxicillin are very rare. 

Infectious Disease

Endoscopic Removal: If a part of the tapeworm is long and leads to intestinal obstruction or any mechanical complications, an endoscopic method may be used to get rid of the worm. This is especially useful if the worm is visible and can easily penetrate in the gastrointestinal tract. 

Surgical Intervention: Surgical intervention may be necessary in very limited circumstances, for example if endoscopic removal is not possible, or if complications such as severe obstruction or perforation are present. This would require a laparotomy or other surgeries to drain or remove the tapeworm or manage the complication. 

Infectious Disease

Managing diphyllobothriasis involves several phases: diagnosing the infection and its severity through a clinical examination and a stool sample, treating the infection through antiparasitic medications such as praziquantel or niclosamide to eliminate the parasite and prognosis through follow up tests and nutritional evaluation. In case of complications the use of medications, surgical procedures may be required. Educational measures are preventing, and long-term treatment implies surveillance of relapses and possible consequences in nutrient metabolism.