B81.0 Anisakiasis

Name of the Condition

• Anisakiasis

Summary

Anisakiasis is an infection caused by the larvae of nematodes (roundworms) belonging to the genus Anisakis. These parasites primarily affect the gastrointestinal tract, leading to inflammation and symptoms that can range from mild discomfort to severe abdominal pain. The condition occurs after consuming raw or undercooked seafood contaminated with Anisakis larvae.

Causes

The infection is caused by ingesting larvae of Anisakis nematodes, which are typically found in raw or undercooked fish and squid. The larvae penetrate the gastrointestinal mucosa, triggering an inflammatory response. Transmission occurs through consumption of contaminated marine products, particularly those from cold-water regions where Anisakis is endemic.

Risk Factors

• Consumption of raw or undercooked fish or squid.
• Eating seafood from regions with high Anisakis prevalence.
• Poor food preparation practices, such as inadequate cooking or freezing.
• Dietary habits that include raw seafood (e.g., sushi, sashimi).

Symptoms

• Abdominal pain, often localized to the epigastrium.
• Nausea and vomiting.
• Fever.
• Allergic reactions, including urticaria or anaphylaxis in some cases.
• Eosinophilia (elevated eosinophil count in blood).

Diagnosis

Diagnosis is based on clinical presentation, history of raw seafood consumption, and laboratory findings. Endoscopic examination may reveal larvae embedded in the gastrointestinal mucosa. Serological tests for Anisakis antibodies can support the diagnosis, though they are not always definitive. Imaging studies may be used to identify complications like intestinal obstruction.

Treatment Options

Treatment involves endoscopic removal of the larvae when accessible. Symptomatic relief with analgesics and antiemetics may be provided. In cases of severe allergic reactions, antihistamines or corticosteroids are used. Antibiotics are not typically effective against the larvae but may be prescribed for secondary bacterial infections.

Prognosis and Follow-Up

Prognosis is generally good with timely removal of the larvae. Most patients recover fully without long-term complications. Follow-up may include monitoring for recurrence of symptoms or allergic reactions, especially if the larvae were not fully extracted.

Complications

• Intestinal perforation or obstruction.
• Severe allergic reactions, including anaphylaxis.
• Chronic abdominal pain or granuloma formation.
• Secondary bacterial infections.

Lifestyle & Prevention

• Thoroughly cook fish and squid to an internal temperature of at least 63°C (145°F).
• Freeze seafood at -20°C (-4°F) for at least 7 days to kill larvae.
• Avoid consuming raw or undercooked seafood from high-risk regions.
• Practice proper food handling and hygiene when preparing seafood.

When to Seek Professional Help

Seek medical attention if you experience severe abdominal pain, vomiting, fever, or signs of an allergic reaction (e.g., hives, difficulty breathing) after consuming raw or undercooked seafood. Prompt evaluation is important to prevent complications.

Tips for Medical Coders

Document the clinical findings, including symptoms, exposure history, and diagnostic methods. Specify if the infection is confirmed by endoscopy or serology. Ensure the code B81.0 is used for anisakiasis and not confused with other intestinal helminthiases. Include details about complications or allergic reactions if present, as these may require additional coding.