The lung fluke and the various liver flukes that exist are transmitted by the fecal or oral route and could be of great danger to the affected person. How can these diseases be prevented and/or treated?
Pulmonary Fluke (Paragonimus Westermani)
Paragonimiasis Westerni is an agent of paragonimiasis. Its prevalence is highest in the Far East, Central America, Africa and India. It has an egg-shaped body that is 7.5 to 16 mm long and is transmitted when ingested (as metacercaria cysts) in crabs or lobsters. Its final host is carnivorous mammals, pigs, humans, etc. and the intermediate hosts are the snail (sporocyst, redia, cercaria) and crabs or crayfish (metacercaria). Its infective stage is the Metacercariae form and the clinical picture of this disease is as follows: chronic cough with bloody expectoration, dyspnea, pneumonia due to pleuritic chest pain. Laboratory diagnosis is the determination of their eggs in sputum or feces.
The World Health Organization has recommended the use of two important parasitic agents such as triclabendazole and praziquantel (especially this one) for the treatment of paragonimiasis. It can be prevented by cooking crabs and crayfish properly.
Biliary flukes (liver)
CLONORCHIS SINENSIS
A small eastern gall fluke that causes clonorchiasis. It is very common in the Far East, China, Japan and Vietnam. It is located in the bile ducts, gallbladder, and pancreas of humans. Adult worms measure 1 to 2 cm; the eggs are small and brown. It is transmitted by the fecal-oral route (ingestion of contaminated raw, frozen, dried, pickled, and salted fish containing metacercariae). Its infective stage is the metacercaria.
The clinical manifestations of the disease are as follows: Cholecystitis and cholelithiasis, hepatic colic, associated with profound weight loss and diarrhea. An individual fluke can live 15 to 30 years in the liver. In humans, severe liver fluke infection can cause liver cirrhosis and death. They can cause adenomatous hyperplasia, which increases the risk of cholangiocarcinoma (carcinoma of the epithelium of the bile ducts). The final host is carnivorous mammals and humans, while the intermediate hosts are as follows; first of all, the snail (miracidium, sporocyst, rediae, cercariae), second fish genus Cyprinidae- the family that includes carp and goldfish (metacercariae).
The laboratory diagnosis is the determination of immature eggs in the feces and in the liquid of the biliary drainage or duodenal aspirate. Treatment is based on the administration of albendazole or praziquantel. They are very effective antiparasitic drugs for the eradication of the parasite. The disease can be prevented by proper cooking of fish and proper disposal of human waste.
FASCIOLA HEPATICA
It is an agent of fascioliasis. It is a biliary (liver) fluke. Relatively common large fluke. It is endemic to the Far East and is found in the bile ducts, gallbladder, and pancreas of humans. It has large sizes (3-5 cm) and a conical shape of the body; They have sucking discs (oral and abdominal) that provide them with movement. The multibranched uterus is situated below the abdominal sucking disc. The testicles are also branched and located in the middle part of the body. The transmission of this disease is through the fecal-oral route (ingestion of water, some non-aquatic plants and vegetables, containing adolescents). Its invasive stage is adolescence.
The clinical symptoms of the manifestation of fascioliasis are: The parasites obstruct the bile ducts and lay eggs inside them, leading to cholelithiasis (gallstones). Biliary obstruction can occur, sometimes causing biliary cirrhosis. Final hosts are herbivorous mammals (horses, pigs) and humans. The intermediate host is the snail Limnea truncatula. The eggs are excreted in the feces of the infected host. The egg hatches and forms a miracidium in the water. It penetrates a host snail. In the snail, after stages such as sporocyst and redia, free-growing cercariae are released into the water. The cercariae lose their tails and become covered by a thick membrane and become adolescents. They are collected on watercress plants. Adolescariae are ingested by humans (final host) where they transform into juvenile trematodes and then adults.
The diagnosis is the determination of eggs in the feces. An egg has large sizes, thick membrane, yellow color, and small cover at one pole. Treatment is based on therapeutic antiparasitic drugs. Medications such as triclabendazole and praziquantel, but the drug of choice is bithionol, which is currently only available in the United States of America. Prevention of fascioliasis involves not eating wild aquatic vegetables.
OPISTORCHIS FELINEUS
It is a small biliary fluke that causes opisthorchiasis. It prevails in Siberia and is localized in the bile ducts, gallbladder and liver. It is flat, the length of the body is 4-13 mm. In the middle part of the body, there is a branching uterus. Behind it, there is a round ovary. There is a rosella-shaped testicle at the back of the uterus, a diagnostic sign of Opisthochia felineus. Transmission occurs through ingestion of contaminated raw, frozen, dried, pickled, and salted fish, which contain metacercariae. The invasive stage is metacercariae cysts in the muscles of fish. The clinical manifestations are: cholecystitis and cholelithiasis, hepatic colic, cirrhosis. The clinical picture is very similar to Clonorhis infection. The infection may remain latent for several years before presenting clinically. The final hosts are carnivorous mammals and humans. The first intermediate host is the snail of the genus Bithynia leachi and the second host is the fish. The life cycle of Opisthochis felineus is the same as that of Clonorshis sinensis.
The diagnosis of opisthorchiasis is the determination of eggs in feces, in biliary drainage liquid or duodenal aspirate. The eggs are 15-30 micrometers in size, oval in shape and yellow in color. The outer membrane is thick and there is a cover at the front of the egg. The internal structure of the egg is microgranular. Generally, a single dose of Praziquantel can cure Opisthorchiasis with ease. Prevention consists of not eating undercooked or contaminated raw, frozen, dried, pickled and salted fish: eradication of host snails where possible.
DICROCOELIUM LANCEATUM
It causes Dicrocoeliasis and has its effect all over the world. It is usually located in the bile ducts, gallbladder and liver of herbivorous mammals (cattle horses). Very rare in humans. The worms are 1 cm long with a lanceolate body shape; The intestine (gut) has two unbranched canals which are situated on the lateral sides of the body. Two round testicles are situated at the front of the body, which is the basic diagnostic sign of Dicrocoelium Lanceatum. Its transmission is by ingestion of plants with ants, which contain metacercariae. Its clinical manifestation is very similar to fascioliasis and its final hosts are herbivorous mammals (cattle, horses). Its first intermediate hosts are snails of the genera Zebrina and Helicela, while its second intermediate hosts are ants of the genus Fornica. The diagnosis is based on the determination of immature eggs in the feces. One egg is oval in shape, smooth membrane, brown in color, a shell is present at the front end.
Its occurrence is very rare and therefore there are different suggestions about its treatment therapy. First, its standard treatment is praziquantel and a more successful therapy is the use of triclobendazole which has been shown to be more effective in treating humans, goats and even sheep. Prophylactic measures are: eradication of snails, ants and when possible; deworming of cattle.
These diseases are of economic importance to man and therefore information about them is very essential.