Opisthorchiasis: an overview

Opisthorchiasis (lat. Opisthorchosis, Engl. Opisthorchiasis, French. Opisthorchiase) - natural focal biogelmintoz with fecal-oral route of transmission mechanism, characterized by a long passage and a primary lesion hepatobiliary and pancreatic disease caused by penetration into the human body and development in it sexually mature form of helminth - cat fluke

ICD-10 code

B66.0. Opisthorchiasis.

Epidemiology of opisthorchiasis

Opisthorchiasis is widespread on the Eurasian continent. It is registered in a number of countries in Eastern and Central Europe. In Russia and the CIS, the most extensive foci of infection are found in Western Siberia, Northern Kazakhstan (the Ob and Irtysh basins), the Perm and Kirov regions and the Kama, Vyatka, Dnieper, Desna, Seym, Northern Donets, and Southern Bug basins. The most tense situation is noted in Western Siberia, where the largest Ob-Irtysh infestation site is located.

The source of infection are people infected with opisthorchis, as well as domestic animals (cats, pigs, dogs) and wild carnivores, whose diet includes fish.

Infection of a person occurs when eaten raw or untreated by heating, freezing or salting fish containing viable metacercariae.

The natural susceptibility of people to the opisthorchiasis is high. The highest incidence rates are recorded in the age group from 15 to 50 years. A few more sick men. Infection, as a rule, occurs in the summer-autumn months. Often there are repeated cases of infection after a cure. Immunity is unstable. Risk groups are new settlers who have arrived on endemic territories and thoughtlessly adopting local traditions of eating unprocessed fish.

Invasion of the rural population in the Middle Ob reaches 90-95%, and often infants and children of the first year of life. By the age of 14, the children's affection with this helminthiasis is 50-60%, while in the adult population it is almost 100%.

Opisthorchias of lesser intensity are found in the basins of the Volga and Kama, the Urals, the Don, the Dnieper,

Northern Dvina, etc. The centers of opisthorchiasis caused by O. viverini are in Thailand (in some provinces of which up to 80% of the population is affected), and also in Laos, India, on. Taiwan and in several other countries of Southeast Asia. On non-endemic territories, imported cases of opisthorchiasis and even group diseases are recorded. In such cases, the infected fish is the factor of infection.

With opisthorchiasis, many infectious diseases occur in more severe forms. In patients with opisthorchiasis who underwent typhoid fever, the chronic carrier of salmonella is formed 15 times more often.

O. Felineus develops with a triple change of hosts: the first intermediate (mollusks), the second intermediate (fish) and the final (mammals). The final hosts of the parasite include man, cat, dog, pig and various species of wild mammals, whose diet includes fish (fox, Arctic fox, sable, ferret, otter, mink, water rat, etc.).

From the intestines of the final hosts, fully mature opisthorchis eggs are released into the environment. Eggs of parasites trapped in a body of water can remain viable for 5-6 months. In the water, the egg is swallowed by the mollusc of the genus Codiella, in which it releases miracidia, which then becomes a sporocyst. It develops redia, then penetrating into the liver of the mollusk, where they form the cercariae.

All larval stages develop from the embryonic cells parthenogenetically (without fertilization). At the transition from one stage to the next, the number of parasites increases.

The time of development of parasites in the mollusc depending on the temperature of the water can be from 2 to 10-12 months. Upon reaching the invasive stage, the cercariae exit the mollusk into the water and, with the help of the secret of the special glands, attach themselves to the skin of the fish of the carp family (tench, ide, dace, carp, bream, barbel, roach, etc.). Then they are actively introduced into the subcutaneous tissue and musculature, lose the tail and after a day are encysted, becoming metacercariae, the size of which is 0.23-0.37 x 0.18-0.28 mm. After 6 weeks, the metacercariae become invasive, and the fish containing them can serve as a source of infection for the final hosts.

In the intestines of the definitive host, under the influence of duodenal juice, the larvae are released from the cysts and migrate to the liver along the common bile duct. Sometimes they can also get into the pancreas. After 3-4 weeks from the beginning of infection of the final hosts, the parasites reach sexual maturity and after the fertilization they begin to excrete the eggs. The life span of a cat fluke can reach 20-25 years.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]

What causes opisthorchiasis?

Opisthorchiasis caused by Opistorchis felineus (cat's fluke) belongs to the type of flatworms (trematodes), a class of flukes. Has a flat elongated body 8-14 mm long and 1-3.5 mm in diameter; is equipped with two suckers - the oral and abdominal. Opisthorchy are hermaphrodites. Eggs are pale yellow, almost colorless, with a smooth two-contour shell, which has a lid on a slightly narrowed pole and a slight thickening at the opposite end. The eggs are 23-24x11-19 microns in size.

The causative agent has a complex developmental cycle. In addition to the final, he has two intermediate and additional hosts. In definitive (basic) hosts, the helminth parasitizes in the sexually mature stage of its development. Of the bile ducts, gallbladder and ducts of the human pancreas and carnivorous mammals (cats, dogs, fox, arctic fox, sable, wolverine, domestic pig, etc.), parasite eggs along with bile enter the intestine and then enter the environment.

Pathogenesis of the opisthorchiasis

After eating invasive fish, metacercariae enter the stomach and duodenum, and within 3-5 hours reach intrahepatic bile ducts - the place of their main habitat in the body of the final host. In 20-40% of infected individuals, opisthorchia is found in the ducts of the pancreas and gall bladder. In the process of migration and with further development, they secrete enzymes and metabolic products that exert a sensitizing and direct toxic effect on the body.

The worm that causes opisthorchiasis is found in man K.N. Vinogradov in 1891 and named it Siberian fluke, as the worm has two suckers. Sexually mature worm has a length of 4 to 13 mm and a width of 1 to 3 mm. The oral sucker is located on the head of the parasite. There is a second abdominal sucker on the body of the worm. Sexually mature worm per day can produce up to 900 eggs. The cycle of parasite development involves its presence in the body of two intermediate and one final host. The eggs of the opisthorchus, when ingested, swallow the mollusks Bithynia inflata. In the intestine of this mollusk, the larva, miracidia, emerges from the egg. The latter in the body of the mollusc undergoes several stages and turns into redia, from which eventually the cercariae emerge. Cercariae leave the body of the mollusk, go into the water and are introduced through the scales into the body of the muscles of the fish of the carp family. There they become metacercariae and are found until the final host has eaten the fish. The final hosts of opisthorchs are man, cats, dogs, wolves, foxes and pigs. Six weeks after infection of the final hosts, sexually mature worms begin to release eggs into the environment.

Sexually mature opisthores parasitize the ducts of the liver and pancreas. The degree of parasitic invasion can be different - from several individuals to several thousand. There is opisthorchiasis in two phases - acute and chronic. The acute phase of opisthorchiasis lasts from 4 to 6 weeks after infection. It proceeds as an acute allergic disease with sensitization of the body with the products of the life of the opisthorchia. The immune reaction in the acute stage of opisthorchiasis leads to the destruction of the mucous membrane of habitats of parasites, the walls of blood vessels and the nervous system. The chronic stage of the disease can last for years and lead to serious changes in the habitat of parasites. Opisthorchy, parasitizing the ducts of the liver and pancreas, have mechanical, toxic and infectious-allergic effects on the walls of the bile ducts and ducts of the pancreas. Mechanical damage to the mucous membrane of the ducts by hooks and suckers of parasites leads to its traumatization and attachment of a secondary infection, which causes productive inflammation of the duct walls.

Inflammatory and sclerotic changes in the duct wall are most pronounced and clinically significant in the bladder duct and large duodenal papilla and often lead to their sharp narrowing or obliteration. These changes lead to the development of biliary hypertension, the expansion of the intrahepatic ducts and the appearance of cholangioectases under the glisson capsule of the liver.

In the liver parenchyma and in the pancreas, sclerotic processes also occur, leading ultimately to the development of liver cirrhosis and chronic pancreatitis. All described morphological manifestations of opisthorchiasis invasion in combination with secondary infection lead to the development of a number of complications requiring surgical intervention.

What are the symptoms of opisthorchiasis?

Opisthorchosis has an incubation period, which is 2-6 weeks after eating the affected fish. The disease of opisthorchiasis is characterized by polymorphism of the clinical picture.

Opisthorchiasis does not have a single classification. Isolate an acute phase of invasion, which can be asymptomatic or erased in the native inhabitants of endemic regions during reinfusion or superinfection. The clinically pronounced form of the acute phase is observed in individuals arriving in an endemic region. Chronic phase of the disease in the absence of symptoms of the acute phase is regarded as primary chronic: if it is preceded by an acute phase - as a secondary chronic. Organ damage (biliary tract, pancreas, stomach and duodenum) can persist even after the release of the body from opisthorchia, so some authors identify the residual phase of the disease.

In the chronic phase of opisthorchiasis, patients usually complain of persistent aching pain in the liver region, worse on an empty stomach, a feeling of heaviness in the right hypochondrium and dyspeptic phenomena. With the development of complications, the nature of complaints varies.

The most common complication of opisthorchiasis is the stricture of the bladder duct. Clinically, they appear as obturative cholecystitis with pain in the right hypochondrium, positive symptoms of Murphy, Ortner and the presence of an enlarged gallbladder. In 10% of patients, purulent cholangitis and mechanical jaundice are diagnosed. In acute obturative cholecystitis, severe pain in the right hypochondrium with irradiation in the right shoulder and shoulder blade, vomiting and symptoms of purulent intoxication are observed. At palpation, sharp soreness and symptoms of irritation of the peritoneum in the zone of the gallbladder are revealed, the bottom of which often palpates. About half of these patients are treated promptly.

The main sign of strictures of the large duodenal papilla except the pain syndrome is the icteric staining of sclera and skin, acholic feces and dark urine. With concomitant cholangitis, note the hectic temperature and chills with pouring sweat. It should be noted that with stricture of the distal part of the common bile duct and large duodenal papilla jaundice can proceed without a pain attack. The enlarged gallbladder simulates the Courvoisier symptom, which is characteristic for tumors of the head of the pancreas. In severe cases with prolonged opisthorchiasis invasion, sclerosing cholangitis sometimes occurs, characterized by progressive jaundice with hepatosplenomegaly and development of biliary cirrhosis.

The cysts of the liver of opisthorchiasis are not detected as often, they are usually located in the edges of the organ, more often in the left lobe and are retentive. Clinically, they manifest themselves as a pain syndrome in the right upper quadrant in patients with a prolonged course of the disease. When palpating an enlarged, tuberous, slightly painful liver is detected.

Abscess of the liver with opisthorchiasis is a complication of purulent cholangitis. Clinically, they are manifested by the severe condition of patients, severe pain in the right hypochondrium and hectic temperature. The liver is enlarged and painful on palpation. Opisthorchias abscesses refer to cholangiogenic abscesses. They are often multiple.

Opisthorchiasis pancreatitis can be both acute and chronic. Their manifestations are not significantly different from pancreatitis caused by other causes.

How is opisthorchiasis diagnosed?

The diagnosis of "opisthorchiasis" is established on the basis of clinical epidemiological and laboratory data: the use of thermally unprocessed, slightly salted fish in endemic regions; fever, toxic-allergic syndrome; leukocytosis and eosinophilia in the blood; in the chronic phase - the symptoms of cholecystopancreatitis, gastroduodenitis.

Opisthorchiasis is diagnosed with the help of EGDS, cholecystography, duodenal sounding, ultrasound of the abdominal cavity organs, determination of acidity of gastric juice.

Laboratory and instrumental research

Among the laboratory methods of research in the diagnosis of opisthorchias, priority is given to: coprologic examination, duodenal sounding data and immunological responses. In immunological tests, a precipitation reaction is carried out in the gel, but this reaction is also positive for other helminthiases. At coprological research reveal presence in feces of eggs of opisthorchias. In this case, a coprological examination should be carried out several times. When duodenal sounding in the resulting bile, microscopy reveals the eggs of parasites. Especially a lot of them are defined in portion "B".

When ultrasound is detected a large gall bladder and stricture of the cystic duct. Usually this is combined with the expansion of intrahepatic bile ducts and periductal fibrosis. With the stricture of the common bile duct, its extension is noted and cholangioectases are detected. Opisthorchiasis cysts and liver abscesses are also fairly clearly defined with ultrasound. During this study, the presence of peri-choledochal lymphadenitis is also confirmed.

With fibrogastroduodenoscopy, a picture of duodenitis and the imposition of fibrin on the duodenal mucosa in the form of "semolina" are observed. Retrograde cholangiopancreatography reveals the presence of strictures of biliary tracts, cysts, liver abscesses and enlargement of bile ducts, as well as cholangioectasis. A characteristic feature of the strictures of the bile ducts in opisthorchiasis is their rather long length.

During laparotomy, the enlargement of the bile ducts is noted, especially on the lower surface of the liver, mainly in the left lobe of the organ, the presence of cholangioectasis, the large dilated gall bladder, the enlargement of the extrahepatic bile ducts, and the enlarged inflamed perihodoheal lymph nodes. When carrying out intraoperative cholangiography in the case of opisthorchiasis invasion, the mass yield of parasites from the biliary tract is noted, especially after the administration of iodine-containing drugs into the ducts.

Differential diagnostics

When mechanical jaundice with the presence of an extended gallbladder should be carried out a differential diagnosis of opisthorchiasis with tumors of the head of the pancreas. This is especially important in the presence of pseudotumorous opisthorchiasis pancreatitis.

Living in endemic areas, eating raw and dried fish, coprologic examination, duodenal sounding and immunological reactions are guiding signs for correct diagnosis of opisthorchiasis.

[12], [13], [14], [15], [16], [17], [18], [19], [20]

Example of the formulation of the diagnosis

Acute (chronic) opisthorchiasis. Complications: opisthorchiasis obturative cholecystitis, stricture of the distal part of the common bile duct

With jaundice or without it, opisthorchiasis cyst of the liver, opisthorchiasis liver abscess, opisthorchiasis pancreatitis acute or chronic (painful, pseudotumorous, cyst of the pancreas).

[21], [22], [23], [24], [25], [26], [27]

Screening

The screening survey should cover all patients seeking medical care in endemic areas, and include the conduct of coprological, immunological and ultrasound studies.

How is opisthorchiasis treated?

The purpose of treatment is de-worming and elimination of disorders caused by complications of opisthorchiasis. Deworming is carried out on an outpatient basis, and the complications of opisthorchiasis serve as an indication for hospitalization in a surgical hospital.

Opisthorchiasis is treated in a comprehensive way, individually, taking into account the concomitant diseases. Hospitalization of patients is carried out according to clinical indications. Assign a gentle regime, diet number 5 for 6 months.

Medication

For dehelminthization with opisthorchiasis, a one-day course of treatment with biltricid (praziquantel) is used. The course of treatment requires a dose of 60 mg of the drug per kilogram of body weight of the patient. After conducting a course of pre-hepatotropic therapy during the day, the patient takes in 6 doses a required dose of the drug. The effectiveness of such de-worming reaches 80-90%. The next day, control duodenal sounding is performed.

The drug of choice - prazikvantel or its domestic analogue of azinoks. Opisthorchiasis is treated, as a rule, out-patient (except for patients with severe symptoms of acute phase, severe organ damage, toxic-allergic manifestations). In acute phase, therapy is started after arresting fever, eliminating intoxication and allergic symptoms.

Surgery

Surgical treatment is used only in the development of complications of opisthorchiasis invasion. It includes cholecystectomy, interventions on extrahepatic bile ducts and surgery for complications from the liver and pancreas.

The opinion of some surgeons that with opisthorchiasis cholecystitis should be limited to sanation of the gallbladder with cholecystostomy, does not have sufficient grounds. The proof of the groundlessness of this provision is a pronounced violation of the contractile function of the gallbladder during its opisthorchiasis invasion. With opisthorchiasis cholecystitis, the gall bladder does not actually function and turns into a source of chronic infection. In addition, opisthorchiasis cholecystitis is accompanied by concrements of the gallbladder in 90% of cases. Also, in the presence of concrements of the gallbladder, it is impossible to effectively combat the cholangitis detected in 80% of cases. Sanitation of bile ducts through cholecystostomy is not possible due to strictures of the cystic duct. Therefore, with opisthorhozic cholecystitis, cholangitis and strictures of extrahepatic bile ducts, cholecystectomy is considered to be the operation of choice.

The state of extrahepatic bile ducts is necessarily assessed by intraoperative cholangiography and choledochoscopy. In the presence of stricture distal section of the choledochus or large duodenal papilla necessarily restore the passage of bile in the intestine by imposing a holo-odihodoodenoanastomoza or choledochoejnoanastomoza on the bowl that is turned off on the Roux. Endoscopic papillosphincterotomy with opisthorchiasis strictures is performed quite rarely, because the narrowing of the ducts in this disease is usually prolonged and can not be eliminated by intervening on the terminal section of the common bile duct.

The formation of biliodigestive anastomoses with opisthorchiasis strictures should be combined with nadastomosis drainage for subsequent sanation of extrahepatic bile ducts. Daily flushing of the ducts with iodine-containing solutions and antibiotics in the postoperative period makes it possible to eliminate cholangitis and, in 90% of cases, relieve patients from opisthorchiasis without additional therapy.

With opisthorchiasis liver cysts, liver resection is performed, and in the case of opisthorchiasis liver abscesses, drainage is performed. Single abscesses can be removed by resection of the affected parts of the liver.

In opisthorchoid cysts of the tail and body of the pancreas, resection of the affected parts with a cyst is performed. In the cysts of the head, resection of the anterior wall of the cyst and cryodestruction of the remaining walls is performed.

Possible postoperative complications. With a radical operation with the restoration of bile passage into the intestine, the probability of complications is small. After surgery for cysts, there may be a development of biliary peritonitis and postoperative pancreatitis. The use of cryotherapy reduces the risk of developing pancreatitis. Mortality after cholecystectomy and operations on the biliary tract is 2-3%.

Further management

After operations on the gall bladder and biliary tract the patient is disabled for three to four weeks. After interventions on the liver and pancreas, the period of incapacity for work is two months, and the facilitated working conditions are necessary for 6-12 months.

How to prevent opisthorchiasis?

To prevent opisthorchiasis, one should not eat non-thermally processed carp fish.

What prognosis is opisthorchiasis?

In the absence of bacterial complications, opisthorchiasis usually has a favorable prognosis. Serious prognosis - with the development of purulent processes in the biliary tract, bile peritonitis and acute pancreatitis: unfavorable in the development of cholangiocarcinoma or liver cancer.