What Is Clonorchiasis?
Clonorchiasis is a disease caused by Clonorchis Sinensis (C.Sinensis). The condition is also known as the Chinese liver fluke disease because Clonorchis, or Chinese liver fluke, is a fish-borne trematode worm. Clonorchiasis is classified as one of the world's most neglected tropical diseases by the World Health Organization (WHO). Cats, dogs, and humans are among the fish-eating mammals that are frequently infected with Clonorchis Sinensis. Fishes that have been consumed uncooked or undercooked can potentially infect people. When people are infected, Clonorchiasis Sinensis resides in their biliary (liver) systems. If these parasites are not identified and treated promptly, they may cause serious complications.
What Causes Clonorchiasis?
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In endemic areas of the world, eating fish infected with C. Sinensis is the primary cause of clonorchiasis.
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From feces, C. Sinensis eggs enter the aquatic environment. The first intermediate host, freshwater snails, then eats these eggs, releasing miracidia, which evolve through a number of stages to become cercariae. Once liberated from the snail, the cercariae freely swim through the water until they enter a freshwater fish. Subsequently, a higher mammal, such as a human, ingests the diseased fish after that and becomes infected.
Who Is Affected by Clonorchiasis?
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C. Sinensis is primarily prevalent in the Eastern hemispheres of the world, primarily in East Asia and parts of Russia. It used to be common in Japan as well, but with the development of agriculture after World War II, it has vanished. East Asia, comprising Korea, China, Taiwan, and northern Vietnam, as well as far eastern Russia, are the endemic regions. Clonorchiasis cases have been observed in non-endemic regions, such as the United States, usually in Asian immigrants or as a result of eating contaminated food.
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The risk of disease spreading to neighboring nations is also increased by emigrants or travelers from endemic regions.
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An estimated 15 to 20 million persons are infected with C. Sinensis currently, with 13 million of those cases occurring in China alone.
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In these areas, the frequent consumption of uncooked fish puts more than 200 million people at risk of infection.
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Males are more likely to become infected than females are, and infection rates rise with age, peaking in the fifth decade of life.
What Are the Symptoms Associated With Clonorchiasis?
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In humans, mild infections of acute clonorchiasis may be asymptomatic or show mild symptoms.
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After consuming an infected fish, symptoms start to show about 10 days to 30 days later and last for about two weeks to four weeks.
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Most infected individuals are thought to have a mild infection (fewer than 100 flukes) during the initial stages of the infection and hardly ever exhibit symptoms.
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Symptoms, such as jaundice (yellowish discolorations of skin), inflammation of the bile duct system, pain in the right upper abdominal region, nausea, vomiting, loss of appetite, tiredness, and fevers, can appear in patients with very high parasite loads (more than 20,000).
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Gallstones, especially calcium carbonate stones, are more likely to form due to clonorchiasis.
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Additionally, people with clonorchiasis are more likely to develop pancreatitis and liver abscesses.
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Children who have a high parasite load are at risk of developing persistent diarrhea, malnutrition, and anemia, all of which can cause developmental delays.
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The most severe form of clonorchiasis may be chronic, which develops over time as a result of repeated, extended infections. The presence of worms in the walls of the smaller bile ducts leads to chronic inflammation and fibrosis, which destroys the liver parenchyma.
How Is Clonorchiasis Diagnosed?
Clonorchiasis is diagnosed in the following ways:
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Stool Examination: The duration and severity of the infection have a direct impact on the clinical consequences. The number of eggs in the stool, which are observable after three weeks to four weeks, can be used to estimate the worm load. The more eggs present in the stool, the more symptoms will be manifested. Detecting eggs in the stool is the gold standard for diagnosing C. Sinensis. Because eggs are typically not visible in the stool when there is biliary obstruction, the absence of eggs in stool does not rule out clonorchiasis diagnosis. One of the common diagnostic procedures is a direct stool smear using the Kato-Katz method.
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Endoscopic Retrograde Cholangiopancreatography (ERCP): With the help of endoscopic retrograde cholangiopancreatography, parasites can be detected directly in duodenal aspirates or biliary secretions. Alternative markers of the severity of the infection are the serum concentration of IgG4 (immunoglobulin G4) and bile.
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Polymerase Chain Reaction: Although it may not always be available, polymerase chain reaction (PCR) is another method used for identifying C. Sinensis and this diagnostic method has good sensitivity and specificity.
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Imaging Tests: In order to ascertain the location, development, and severity of the infection, imaging techniques like ultrasound, computed tomography (CT) scan, and magnetic resonance imaging (MRI) are helpful. Patients with Clonorchis Sinensis infection frequently exhibit diffuse dilatation of the intrahepatic bile ducts on ultrasonography, although the observation by itself is insufficient to confirm the diagnosis of clonorchiasis.
How Is Clonorchiasis Treated?
Clonorchiasis can be treated in the following ways:
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The cornerstone of clonorchiasis treatment is the use of Praziquantel (a medication used to treat parasitic worm infections) drug. The World Health Organization (WHO) advises either 40 mg (milligram) per kg (kilogram) in a single administration or 25 mg per kg taken orally three times daily for two to three days to treat the condition. This drug cures the infection in about 90 % of the cases. Re-treatment is required in cases of severe parasite infections or persistent egg presence in stool following treatment. Praziquantel can cause side effects like nausea, vomiting, headaches, and abdominal pain.
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Alternative drugs that can be used to treat clonorchiasis are Albendazole (anthelmintic), Tribendimidine (anthelmintic), etc.
Conclusion
Clonorchiasis is an infection caused by Clonorchis Sinensis and transmitted through uncooked fish and other contaminated food. The severity of the symptoms depends upon the worm load that can be evaluated through stool examination. The treatment and prognosis of the infection also depend on the number of Clonorchis Sinensis eggs found in the stool sample of the patient. The reversibility of pathological changes caused by Clonorchis Sinensis depends largely on the timing of treatment initiation, so if Praziquantel treatment is delayed, the recovery time for pathological changes to the bile duct may last up to twelve weeks, and even longer or these changes can be irreversible if the infection is severe or persistent.
