Opisthorchiasis is a helminthic disease caused by flat parasitic worms of the fluke class and occurring with damage to the hepatopancreatobiliary system. The course of opisthorchiasis is characterized by fever, abdominal pain, impaired appetite, skin rashes, jaundice, hepatosplenomegaly, dyspepsia, asthmatic bronchitis, asthenovegetative syndrome. Diagnosis of opisthorchiasis is based on the detection of opisthorchis eggs in duodenal contents and in feces, the results of serological reactions, data from biochemical blood analysis, instrumental studies (ultrasound, cholecystocholangiography, CT). For the treatment of opisthorchiasis, anthelmintic (praziquantel, azinox), choleretic and enzyme preparations are used.
ICD 10
B66.0 Opisthorchiasis
General information
Opisthorchiasis is an extra–intestinal helminthiasis from the group of trematodoses, the pathogens of which parasitize in the bile ducts of the liver and pancreas, causing polymorphic clinical manifestations. The greatest incidence is registered among people aged 15 to 50 years, mainly men. The danger of opisthorchiasis is that with a prolonged course it increases the risk of developing liver cancer and pancreatic cancer.
Causes
The development of opisthorchis occurs with a three-fold change of hosts: the first intermediate host is mollusks, the second intermediate is freshwater fish of the carp family (bream, carp, tench, dace, ide, roach, etc.) and the final one is mammals (cat, dog, fox, otter, arctic fox, sable, man) that feed on fish. The final hosts secrete eggs with larvae into the external environment along with feces. Once in the pond, the eggs are swallowed by freshwater mollusks of the genus Codiella, in whose body they undergo changes: first, a miracidium comes out of the egg, which successively turns into a sporocyst, redia and cercaria. Tailed larva (cercarium) it leaves the body of the mollusk and attaches to the body of cyprinid fish in the reservoir, penetrates into the connective and muscular tissue, where it encystes, turning into a metacercarium. Being in the body of fish, after 6 weeks the larvae become invasive, i.e. they acquire the ability to cause opisthorchiasis in the final hosts.
Infection of humans and animals occurs when eating invasive, poorly processed (raw, lightly salted) fish. In the gastrointestinal tract of the final host, under the action of duodenal juice, the capsule and the shells of the larvae dissolve, resulting in metacercariae migrating into the common bile duct, intrahepatic bile ducts, as well as into the ducts of the pancreas. In the hepatopancreatobiliary system, after 3-4 weeks, the metacercarium turns into a mature opisthorchis capable of producing eggs. The full cycle of helminth development from the egg stage to the mature individual lasts 4-4.5 months. Human invasion of opisthorchis can vary from several units to tens of thousands. In the body of the final host, the cat fluke can parasitize for 20-25 years.
Pathogenesis
The nature and severity of pathological processes characterizing the course of opisthorchiasis depend on the massiveness and duration of invasion, the state of the immune system. Depending on these factors, the course of opisthorchiasis can be erased or manifest; mild, moderate and severe. In the pathogenesis of opisthorchiasis, there are early (acute) and late (chronic) stages.
In the acute stage of helminthiasis, toxic-allergic reactions that develop in response to the action of parasite metabolites on the host organism dominate. They are accompanied by increased permeability of the vascular wall, perivascular edema and eosinophilic infiltration of the stroma of various organs, the formation of necrotic foci in the liver parenchyma. Damage to the epithelium of the bile ducts by flukes causes hyperplasia of goblet cells, cystic expansion of small bile ducts. With chronic opisthorchiasis, sluggish inflammation develops in the walls of the bile ducts, connective tissue overgrowth is detected, and small bile ducts are often blocked by helminths. These processes lead to the development of secondary bacterial cholangitis, biliary dyskinesia, the formation of gallstones, in severe cases – to cirrhosis of the liver and portal hypertension. Pancreatic lesions in opisthorchiasis are mainly determined by swelling of the gland and a violation of the outflow of pancreatic secretions, which is accompanied by a carpal expansion of the tubules, proliferative canaliculitis and fibrosis of the organ.
Symptoms
The acute phase of opisthorchiasis manifests 2-4 weeks after infection. A mild form of helminthiasis begins with a sudden jump in body temperature to 38 ° C and the subsequent preservation of subfebrility for 1-2 weeks. At this time, patients experience weakness, abdominal pain, and note the unstable nature of the stool. In peripheral blood with a mild course of opisthorchiasis, moderate leukocytosis and eosinophilia up to 15-20% are detected.
The moderate form of opisthorchiasis proceeds with fever (up to 39 ° C and above), which lasts about 3 weeks. Myalgia and arthralgia, urticaria skin rashes, catarrh of the upper respiratory tract, enlargement of the liver and spleen, vomiting, diarrhea, asthmatic bronchitis are characteristic. Leukocytosis, eosinophilia increase to 25-60%, ESR increases.
Severe forms of acute opisthorchiasis develop in 10-20% of patients and can occur in typhoid-like, gastroenterocolitic, hepatocholangitic and respiratory variants. Symptoms of typhoid-like variant of opisthorchiasis include high fever, chills, lymphadenitis, polymorphic skin rash, dyspepsia. In the clinic, the phenomena of intoxication and allergization prevail; toxic-allergic damage to the central nervous system or myocardium is possible. In the gastroenterocolitic form of opisthorchiasis, a clinical and pathomorphological picture of gastritis (catarrhal, erosive), gastroduodenitis, gastric and duodenal ulcers, enterocolitis develops. These conditions are accompanied by a decrease in appetite, nausea, pain in the epigastrium and right hypochondrium, diarrhea. During the hepatocholangitic variant of acute opisthorchiasis, jaundice, hepatosplenomegaly, abdominal syndrome of the type of hepatic colic or shingles prevail. Pathological syndromes may include hepatitis, cholangitis, cholecystitis, pancreatitis. With the involvement of the respiratory organs (respiratory variant of opisthorchiasis), tracheitis, asthmoid bronchitis, pneumonia, pleurisy, fever develops.
Chronic opisthorchiasis most often occurs by the type of biliary dyskinesia, cholangiohepatitis, cholangiocholecystitis, cholelithiasis, chronic pancreatitis, gastritis, duodenitis. There are signs of asthenovegetative syndrome: weakness, fatigue, irritability, emotional instability, headache, sleep disorders, increased sweating. Dystrophic changes of the myocardium may develop, manifested by pain behind the sternum, tachycardia, arterial hypotension. Long-term course of chronic opisthorchiasis can be complicated by cirrhosis of the liver, purulent cholangitis, gallbladder phlegmon, biliary peritonitis, primary liver and pancreatic cancer.
Diagnosis
During the diagnosis of opisthorchiasis, epidemiological information is taken into account, indicating the patient’s stay in endemic foci, eating freshly frozen, lightly salted, insufficiently heat-treated fish. A characteristic change in the biochemical samples of the liver and pancreatic enzymes is an increase in bilirubin, transaminases, amylase and lipase. The data of instrumental studies (FGDS, ultrasound of the hepatoduodenal zone and pancreas, cholecystography, CT, MRI of the liver and biliary tract) show signs of gastroduodenitis, biliary dyskinesia, cholecystitis, cholangitis, hepatitis, pancreatitis.
For the purpose of parasitological confirmation of opisthorchiasis, a microscopic examination of the duodenal contents and feces, in which cat fluke eggs are found, is carried out. To increase the probability of detecting helminth eggs before duodenal probing and coproovoscopy, it is advisable to prescribe Demyanov tubes and choleretic drugs to the patient. An enzyme immunoassay allows to identify anti-hemorrhagic antibodies in the blood serum. Due to the polymorphism of clinical symptoms, the course of acute opisthorchiasis may resemble viral hepatitis, food poisoning, typhoparathyphosis group diseases, the migration phase of ascariasis and ankylostomidosis.
Treatment
Treatment of opisthorchiasis is carried out in stages. At the first stage, preparatory therapy is prescribed, including choleretic and antispasmodic drugs, H1-histamine receptor blockers; according to indications, short courses of antibiotics. In addition to drug therapy, physiotherapeutic treatment is carried out (electrophoresis of magnesium sulfate, magnetotherapy, microwave therapy). The purpose of the preparatory stage is the normalization of bile secretion and bile outflow, relief of the inflammatory process in the gastrointestinal tract and biliary tract.
As part of the main stage of treatment of opisthorchiasis, anthelmintic chemotherapy is prescribed. Praziquantel and its analogues proved to be the most effective in destroying parasites. After deworming, blind probing, pulsed magnetic therapy, and electrical stimulation of the diaphragmatic nerve are performed to evacuate opisthorchis with bile. In the case of severe toxic-allergic syndrome, the appointment of antihistamines, glucocorticoids, infusion therapy is required. Monitoring the effectiveness of antiparasitic treatment involves conducting a three-time examination of feces and duodenal contents.
The final stage of the course of treatment of opisthorchiasis is aimed at removing the decay products of parasites and restoring intestinal biocenosis. For this purpose, tubes with xylitol, sorbitol, mineral water are carried out; choleretic and enzyme preparations, hepatoprotectors, sorbents, pre- and probiotics are prescribed.
Prognosis and prevention
In mild and moderate forms of opisthorchiasis, the prognosis is usually favorable, although cases of repeated helminthic invasion are possible. When purulent cholecystitis and peritonitis occur, the outcome depends on the completeness and speed of surgical care. Prognostically unfavorable is the development of acute liver failure, liver cancer, pancreatic cancer or cholangiocarcinoma.
Actions to prevent infection with opisthorchiasis include therapeutic and preventive work (identification and deworming of the infected), epidemiological measures (protection of reservoirs from contamination by human and animal feces, compliance with the technology of processing and cooking fish, destruction of shellfish), sanitary and educational work (informing the population).