Clonorchiasis: causes, symptoms, diagnosis, treatment

Clonorchiasis is a biohelminthiasis that manifests itself in allergic symptoms at an early stage, and in the chronic stage occurs with predominant damage to the liver and pancreas.

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Epidemiology of clonorchiasis

The source of the invasion are infected people, as well as dogs, cats and wild carnivores. A person becomes infected with this disease by eating raw and insufficiently disinfected fish and shrimp.

The development cycle, like that of opisthorchiasis, occurs with a change of three hosts. The final hosts are humans, cats, dogs, pigs, otters, martens, badgers, rats and some other animals that eat fish. Helminth eggs excreted with feces, when they get into the water, are swallowed by intermediate hosts - mollusks. genera Codiella and others, in whose body the larval development to the cercariae stage takes place. Cercariae leave the mollusk and penetrate into additional hosts, which are many species of carp fish (crucian carp, ide, bream, carp, etc.), less often - gobies and herring; in China, shrimp are also among the additional hosts. Cercariae settle in muscles, subcutaneous tissue and other tissues, where they encyst and turn into metacercariae in about 35 days. When metacercariae enter the gastrointestinal tract of humans or other final hosts, the cyst membrane dissolves, and the released larva enters the liver through the bile duct or portal veins, where it turns into a mature fluke, which begins to lay eggs a month after infecting the host. Development of the larva to the mature stage can also occur in the pancreatic ducts. The lifespan of the Chinese fluke in the host's body can reach 40 years.

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What causes clonorchiasis?

Clonorchiasis is caused by the Chinese fluke - Clonorchis sinensis, which has a flat body, 10-20 mm long, 2-4 mm wide. At the front end of the body is an oral sucker, on the border of the first and second quarter of the body is a smaller abdominal sucker.

In terms of body structure, clonorchis are similar to opisthorchis. Their distinctive features are their larger size and narrower anterior end of the body. The testes of clonorchis, unlike opisthorchis, are deeply dissected, their branches extend beyond the intestinal canals. Hence the name Clonorchis (Greek klonos - branched, Latin orchis - testicle).

The eggs of the pathogen are yellowish-brown, 26-35 x 17-20 µm in size, with a cap on one pole and a tubercle on the other. The anterior end of the egg is noticeably narrowed, the protrusions along the edges of the cap are well defined, which is a distinctive feature from the eggs of opisthorchis.

Clonorchiasis is widespread in China, Japan, Korea and a number of countries in Southeast Asia. In some endemic areas, up to 80% of the population is affected, and in total, millions of people are infected with clonorchiasis. In Russia, clonorchiasis occurs in the Amur basin and in Primorye, the incidence rate is relatively low. However, in the lower Amur region (from Khabarovsk to Komsomolsk-on-Amur) among the indigenous population (Nanai), the incidence rate reaches 25%.

Symptoms of Clonorchiasis

The symptoms of clonorchiasis are basically the same as those of opisthorchiasis. More often than with opisthorchiasis, a sudden onset with pronounced symptoms of allergy is observed. A high fever of a constant or weakening type with chills occurs suddenly. Polymorphic skin rash, eosinophilic infiltrates in the lungs, bronchitis, reactive pleurisy, diffuse changes in the myocardium, myalgia, arthralgia, and lymphadenopathy appear. Approximately 30% of patients have an enlarged spleen.

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Diagnosis of clonorchiasis

In the blood, as a rule, leukocytosis up to 20-30 x 10 ⁹ /l, eosinophilia (up to 70%), an increase in ESR up to 30-40 mm/h are detected. The final diagnosis of "clonorchiasis" is established when helminth eggs are detected in the duodenal contents or feces.

The carcinogenicity of clonorchis has not been reliably established.

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Treatment of clonorchiasis

Treatment for clonorchiasis is basically the same as for opisthorchiasis.