B83.2 Angiostrongyliasis due to Parastrongylus cantonensis

Name of the Condition

• Angiostrongyliasis due to Parastrongylus cantonensis

Summary

Angiostrongyliasis due to Parastrongylus cantonensis is a parasitic infection caused by the larval stages of the nematode Angiostrongylus cantonensis (also known as Parastrongylus cantonensis). The larvae migrate to the central nervous system, leading to neurological symptoms. The condition is often associated with the consumption of contaminated food, particularly raw or undercooked snails, slugs, or other intermediate hosts. Clinical presentation varies based on the intensity of infection and the organs involved, with the most common manifestations affecting the brain and meninges.

Causes

The infection is caused by the larval forms of Parastrongylus cantonensis, which are transmitted to humans through the ingestion of contaminated food or water. Larvae hatch in the intestine, penetrate the intestinal wall, and migrate to the central nervous system, where they can cause inflammation and tissue damage. The parasite’s life cycle involves snails and rats as primary hosts, with humans serving as accidental hosts.

Risk Factors

• Consumption of raw or undercooked snails, slugs, or other intermediate hosts.
• Ingestion of contaminated vegetables or water.
• Residing in or traveling to endemic regions (e.g., Southeast Asia, the Pacific Islands, and parts of the Americas).
• Poor food preparation practices, such as inadequate cooking of potentially contaminated items.

Symptoms

• Severe headache, often described as the most prominent symptom.
• Nausea, vomiting, or neck stiffness.
• Neurological symptoms, including facial palsy, cranial nerve palsies, or altered mental status.
• Meningeal signs, such as photophobia or nuchal rigidity.
• Rarely, ocular or pulmonary involvement.

Diagnosis

Diagnosis is based on clinical presentation, exposure history, and laboratory findings. Cerebrospinal fluid (CSF) analysis may show eosinophilic pleocytosis, a key indicator of parasitic infection. Imaging studies, such as MRI or CT scans, can help identify neurological involvement. Serological tests or detection of larvae in CSF or tissue may confirm the diagnosis, though these are less commonly available.

Treatment Options

Treatment focuses on symptom management and may include analgesics for headache, antiemetics for nausea, and corticosteroids to reduce inflammation. Anthelmintic drugs, such as albendazole or mebendazole, are sometimes used, though their efficacy in this condition is not well established. Supportive care, including hydration and monitoring for complications, is essential.

Prognosis and Follow-Up

Prognosis is generally favorable with appropriate treatment, though recovery may be prolonged. Most patients experience resolution of symptoms within weeks to months, but some may have persistent neurological deficits. Follow-up care should include monitoring for recurrence of symptoms and addressing any long-term complications, such as chronic headaches or cognitive changes.

Complications

• Persistent neurological deficits, including cranial nerve palsies or cognitive impairment.
• Meningitis or encephalitis, which can lead to severe illness.
• Rarely, ocular or pulmonary involvement, which may require specialized treatment.

Lifestyle & Prevention

• Avoid consuming raw or undercooked snails, slugs, or other potential intermediate hosts.
• Thoroughly wash and cook vegetables, especially those from endemic regions.
• Practice good hygiene, including handwashing after handling soil or potential contaminated items.
• Educate travelers to endemic areas about food and water safety.

When to Seek Professional Help

Seek medical attention if you experience severe headache, neck stiffness, or neurological symptoms, especially after potential exposure to contaminated food or water. Prompt evaluation is important to rule out other serious conditions and initiate appropriate management.

Tips for Medical Coders

When coding for angiostrongyliasis due to Parastrongylus cantonensis, use code B83.2. Ensure documentation supports the diagnosis, including clinical symptoms, exposure history, and any laboratory or imaging findings. Note that this code is specific to infections caused by Parastrongylus cantonensis and should not be used for other parasitic infections. Verify that the code aligns with the patient’s clinical presentation and any associated complications.