Introduction:
Food-borne trematodes include lung flukes, intestinal flukes, and liver flukes. Humans are infected if they consume contaminated freshwater frogs, fishes, shellfish, snakes, tadpoles, water plants, and more. It also results in liver and lung diseases.
How Are Foodborne Trematodes Transmitted to Humans?
Four breeds of trematodes cause impairment in an individual. The first host is a snail, the second is a freshwater fish and crustaceans, and the third is a mammal. People get this infection by consuming vegetables and plants that bear the parasite larvae.
What Are the Clinical Features of Foodborne Trematode Infection?
Morbidity associated with food-borne trematode infection depends upon the number of parasitic worms and infection severity. Severe complications like cholangiocarcinoma are associated with Clonorchiasis sinensis and Opisthorchis viverrini. The clinical features are as follows:
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Clonorchiasis Sinensis: The infection with Clonorchiasis sinensis (less than 100 flukes) shows no symptoms or mild symptoms like abdominal ache and diarrhea. Moderate disease (101 to 1000 flukes) may cause diarrhea, fever, rash, edema, loss of appetite, abdominal swelling, and liver enlargement. Patients with severe infection (more than 25000 flukes) present acute pain in the right upper abdominal region; the pain diminishes in a few weeks, followed by chronic symptoms. Chronic complications are liver dysfunction, stones, cholecystitis (inflammation of the gallbladder), cholangitis (inflammation of bile ducts), cholelithiasis (gallstones), abscess (pus), hepatitis (inflammation of the liver), and pancreatitis (inflammation of the pancreas). The most important clinical feature is that patients become susceptible to developing cholangiocarcinoma (a tumor of bile ducts).
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Opisthorchis Viverrini: Symptoms caused due to Opisthorchis viverrini include fatigue (tiredness), flatulence (gas), dyspepsia (indigestion), abdominal pain, mild hepatomegaly (liver enlargement), anorexia (eating disorder making individual obese). Severe symptoms include cirrhosis (liver damage causing scarring and failure), obstructive jaundice (a specific type of jaundice leading to blocked bile ducts), cholangitis (inflamed bile ducts), cholecystitis (inflamed gallbladder), and cholangiocarcinoma (cancer of bile ducts).
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Opisthorchis Felineus: Symptoms associated with felineus infection include fever, abdominal ache, nausea, and vomiting. More severe symptoms include inflammation and obstruction of the biliary tract, pancreatitis, liver abscess, and cholangitis.
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Fasciola Hepatica and Fasciola Gigantica: The symptoms in the acute form of the infection include fever, abdominal ache, dyspepsia (indigestion), hepatomegaly (liver enlargement), splenomegaly (enlargement of the spleen), urticaria (skin rash), ascites (swelling due to accumulation of fluid in the abdomen), jaundice, and respiratory issues. In the chronic condition of the disease, the parasite enters the biliary tract, which leads to jaundice, nausea, epigastric pain, cholangitis, fatty food intolerance, pancreatitis, and cholecystitis.
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Intestinal Flukes: Mild symptoms include diarrhea, abdominal ache, constipation, headache, and dizziness. Moderate symptoms include colic, abdominal pain, diarrhea, nausea, vomiting, fever, and edema of the face, lower extremities, and abdominal wall. Severe infection can be fatal and cause bleeding, abscess, inflammation, and intestinal erosions.
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Paragonimus Species: In the initial stage, symptoms include fever, cough, loss of appetite, chest pain, headache, and blood in the sputum. In later stages, the symptoms include cough with brown sputum, night sweat, chest pain, and eosinophilic meningitis (visual disturbances, headaches, and convulsion).
How to Diagnose Foodborne Trematode Infection?
Complementary methods for the diagnosis of the infection include computerized tomography, ultrasound, harmonic tissue imaging, and magnetic resonance imaging. The imaging tools can detect the pathology of ducts. For example, ultrasound can diagnose stones, fibrosis, and dilatation due to fluke infections. Magnetic resonance imaging and computer tomography can diagnose the diameter of ducts, calcification, fibrosis, and hyperplasia. Tissue harmonic imaging can diagnose stones and bile duct trauma. The various diagnostic techniques are as follows:
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Parasitological Diagnosis: Observation of eggs in the stools and sputum is the most common way to diagnose infection. Samples from the bile, duodenal and gastric fluids can detect eggs. Many diagnostic methods are available that include a thick smear, direct fecal smear, Stoll's dilution egg, sedimentation technique, and formalin ethyl acetate method. Floatation methods with salt or sugar solution are widely used for detection. A very effective technique known as the Flotac method, the fecal egg count method, is used in sheep. The thick smear and formalin ethyl acetate method is an effective and commonly used method for detecting moderate to severe infections.
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Immunodiagnosis: Many tests are available to detect antibodies, including indirect haemagglutination assay, intradermal test, indirect fluorescent antibody test, and indirect enzyme-linked immunosorbent assay. The test uses extracts from the parasite, like adult extract and secretory materials, and can be used in acute and chronic infection levels. Intradermal tests utilize small quantities of antigen in the skin. Immunological reactions are swelling and flaring, which is not recommended nowadays due to less specificity.
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Molecular Diagnosis: Many polymerase chain reaction-based techniques detect the trematode DNA (deoxyribonucleic acid) in stool samples. These tests are very effective as compared with immunodiagnosis and parasitological tests.
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Novel Approaches for Biomarkers: Metabolic profiling utilizes a combination of high-resolution nuclear and mass spectroscopy with statistical examination to rule out the biochemical reaction of the living organism to pathological stimuli.
What Is the Prevention and Treatment for Foodborne Trematode Infections?
Prevention and treatment options for trematode infection include chemotherapy, sanitation, fertilizers, food inspections, and education. The main target is to change unhealthy eating practices. The leading cause of this infection is the consumption of raw seafood. Triclabendazole and Praziquantel are commonly used drugs to control morbidity. Praziquantel is very effective against trematodes (clonorchiasis and opisthorchiasis). Fascioliasis and Paragonimiasis can be treated effectively with Triclabendazole. If symptoms have not subsided, the dosage can be appropriately increased in a gap of 12 to 24 hours.
Conclusion:
The infection with food-borne trematodes is infecting people globally. The main reason is the consumption of raw seafood. People need to be educated about the cause of the illness and how to prevent it. Many diagnostic methods, medications, and vaccines are required. Access to safe and clean water, sanitation, and food safety modes will impact controlling food-borne trematode infections.
