Lung fluke and the various liver flukes in existence are all transmitted fecal orally and could be of great danger to the affected person. How can these diseases be avoided and/or treated?
Lung Fluke (Paragonimus Westermani)
Paragonimiasis Westerni is an agent of paragonimiasis. It is highest in prevalence in the far East, Central America, Africa and India. It has an egg-like body which is from 7.5 to 16mm long and it is transmitted when ingested (in the form of metacercarial cysts) in crabs or crayfish. Its final host is the 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 are as follows: chronic cough with bloody sputum, dyspnea, pleuritic chest pain pneumonia. Laboratory diagnosis is the determination of its eggs in sputum or feces.
World Health organization has recommended the use of two major 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 (Liver)flukes
CLONORCHIS SINENSIS
An oriental small biliary fluke which causes clonorchiasis. It is highly prevalent is the far East, China, Japan and Vietnam. Its localized in the bile ducts, gall bladder, and pancreas of Human. The Adult worms are 1 to 2 cm; the eggs are small and brownish. It is transmitted fecal-orally (ingestion of contaminated raw, frozen, dried, pickled, and salted fish, which contain metacercariae). Its infective stage is metacercariae.
The clinical manifestation of the disease are as follows: Cholecystitis and cholelithiasis, hepatic colic, associated with profound weight loss and diarrhea. An individual fluke may live for 15-30 years in the liver. In humans a heavy infection of liver flukes may cause cirrhosis of the liver and death. They can lead to adenomatous hyperplasia, which increases the risk for cholangiocarcinoma (carcinoma of the bile ductal epithelia). Final host is carnivorous mammals and humans while the intermediate hosts are as follows; firstly, the snail (miracidium, sporocyst, rediae, cercariae), second-fish Cyprinidae genus- the family that includes carp and goldfish (metacercariae).
The laboratory diagnosis is the determination of immature eggs in feces and in fluid from biliary drainage, or duodenal aspirate. Treatment is based on the administration of albendazole or praziquantel. These are very effective anti-parasitic drugs for the eradication of the parasite. The disease can be prevented by adequate cooking of fish and proper disposal of human waste.
FASCIOLA HEPATICA
It is an agent of fascioliasis. It is biliary (liver) fluke. Relatively common large fluke. It is endemic in Far East and localized in the bile ducts, gall bladder, and pancreas of the Human. It has large sizes (3-5cm) and conical form of the body; posses sucking disks (oral and abdominal) that provide them motion. Multibranched Uterus is situated under the abdominal sucking disk. Testis are branched too and situated in the middle part of the body. Transmission of this disease is through the fecal-oral route (ingestion of water, some non-water plants and vegetables, which contain adolescariae). Its invasive stage is the adolescariae.
The clinical symptoms of the manifestation of fascioliasis are: Parasites obstruct bile ducts and lay eggs within them, leading to cholelithiasis (gallstones). Biliary obstruction can occur, sometimes causing biliary cirrhosis. Final hosts are the herbivorous mammals (horses, pigs) and humans. Intermediate host is the snail Limnea truncatula. Eggs are excreted in feces of infected host. Egg hatches and forms a miracidium in water. It penetrates a snail host. In snail, after such stages as sporocyst and redia, free-swinning cercariaes are released to water. Cercariaes lose their tails and are covered by thick membrane and transform into adolescariae. They collect on water cress plants. Adolescariae are ingested by humans (final host) where they transform into juvenile and then Adult fluke.
Diagnosis is the determination of eggs in feces. An egg has large sizes, thick membrane, yellow color and small cover in one pole. Treatment is based on anti-parasite therapeutic drugs. Such drugs as Triclabendazole and praziquantel but the drug of choice is Bithionol which is only available in the United states of America for now. Prevention of fascioliasis involves not eating wild aquatic vegetables.
OPISTHORCHIS FELINEUS
It is a small biliary fluke causing Opisthorchiasis. It is prevalent in Siberia and localized in the bile ducts, gall bladder and liver. It is flat, the body length is 4-13mm. In the middle part of the body, there is a branched Uterus. Behind it, there is a round ovary. There is a rosella-like testis in the back of the uterus- a diagnostic sign of the Opisthochia felineus. Transmission is via ingestion of contaminated raw, frozen, dried, pickled, and salted fish, which contains metacercariae. The invasive stage is the metacercariae cysts in fish muscles. Clinical manifestations are: Cholecystitis and Cholelithiasis, hepatic colic, cirhosis. Clinical picture is very similar to Clonorhis infection. Infection can lay dormant for several years before presenting clinically. Final hosts are carnivorous mammals and humans. First intermediate host is the snail Bithynia leachi genus and the second host is the fish. Life cycle of Opisthochis felineus is the same as of Clonorshis sinensis.
Diagnosis of Opisthorchiasis is the determination of eggs in feces, in fluid from biliary drainage, or duodenal aspirate. Eggs are 15-30micrometer in size, have oval form and yellow color. The outer membrae is thick, and there is a cover in 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 involves not eating undercooked or contaminated raw, frozen, dried, pickled, and salted fish: eradication of snail hosts when possible.
DICROCOELIUM LANCEATUM
It causes Dicrocoeliasis and has its effect worldwide. It is usually localized in the bile ducts, gall bladder and liver of herbivorous mammals (cattle horses). Very rare in humans. The worms are 1cm long with lanceolate form of the body; the intestine (gut) has two non-branched channels which are situated in the lateral sides of the body. Two round testis are situated in the front of the body which is the basic diagnostic sign of the Dicrocoelium Lanceatum. Its transmission is via ingestion of plants with the 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 the snails of Zebrina and Helicela genus while its second intermediate host are ants of the Fornica genus. Diagnosis is based on the determination of immature eggs in feces. An egg have oval form, smooth membrane, brown color, a cover is present in the front end.
Its occurrence is very rare and hence there are different suggestions on its treatment therapy. First, its standard treatment is with praziquantel and a more successful therapy is the use of triclobendazole which has proven more effective in the treating humans, goats and even sheep. Prophylactic measures are: eradication of the snails, ants and when possible; dehelminthization of cattle.
These diseases are of economic importance to man and hence information on them is very essential.
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