B66.0 Opisthorchiasis

Name of the Condition

• Opisthorchiasis

Summary

Opisthorchiasis is a parasitic infection caused by the liver fluke Opisthorchis viverrini or Opisthorchis felineus. The infection primarily affects the bile ducts and liver, leading to inflammation and potential long-term complications. It is commonly associated with the consumption of raw or undercooked freshwater fish containing fluke larvae. The condition may be asymptomatic in mild cases but can progress to more severe disease in chronic infections.

Causes

The infection is caused by ingesting the larvae of Opisthorchis species, which are present in raw or undercooked freshwater fish. The larvae mature into adult flukes in the human bile ducts, where they attach and reproduce, releasing eggs that are excreted in feces. Contaminated water sources or food preparation practices that involve uncooked fish facilitate transmission.

Risk Factors

• Consumption of raw or undercooked freshwater fish from endemic regions.
• Residing in or traveling to areas where Opisthorchis infection is common (e.g., Southeast Asia, Eastern Europe).
• Poor sanitation or lack of access to safe food and water.
• Occupational exposure to contaminated fish or water (e.g., fishing, aquaculture).

Symptoms

• Abdominal pain, particularly in the upper right quadrant.
• Nausea, vomiting, or diarrhea.
• Fatigue, fever, or general malaise.
• Jaundice or dark urine in severe cases.
• Chronic infections may lead to liver enlargement or bile duct abnormalities.

Diagnosis

Diagnosis is typically confirmed through detection of Opisthorchis eggs in stool samples or bile. Imaging studies (e.g., ultrasound) may reveal bile duct abnormalities or liver inflammation. Serological tests can identify antibodies to the fluke, though they are less commonly used. Clinical history of exposure to contaminated fish or water supports the diagnosis.

Treatment Options

• Antiparasitic medications, such as praziquantel or albendazole, are the primary treatment.
• Supportive care, including pain management and hydration, may be necessary for symptomatic relief.
• Follow-up testing is recommended to confirm eradication of the parasite.

Prognosis and Follow-Up

With prompt treatment, most patients recover fully. Chronic infections may lead to long-term bile duct or liver damage, increasing the risk of complications. Regular follow-up, including imaging or stool tests, is advised for individuals with persistent symptoms or chronic disease.

Complications

• Bile duct inflammation (cholangitis) or obstruction.
• Liver fibrosis or cirrhosis in severe, untreated cases.
• Increased risk of bile duct cancer (cholangiocarcinoma) with chronic infection.

Lifestyle & Prevention

• Thoroughly cook freshwater fish to kill larvae.
• Avoid consuming raw or undercooked fish from endemic areas.
• Practice good hygiene and food safety measures.
• Treat contaminated water sources to reduce transmission.

When to Seek Professional Help

Seek medical attention if you experience persistent abdominal pain, jaundice, or unexplained fatigue after consuming raw or undercooked freshwater fish. Early diagnosis and treatment reduce the risk of complications.

Tips for Medical Coders

• Use code B66.0 for confirmed cases of opisthorchiasis.
• Document the specific Opisthorchis species if known, as it may impact clinical management.
• Include details of exposure (e.g., consumption of raw fish) or diagnostic findings to support coding accuracy.
• Differentiate from other fluke infections (e.g., clonorchiasis) based on clinical and laboratory evidence.