Treatment of Rat Lungworm (Angiostrongylus cantonensis) Infection
The recommended treatment for rat lungworm infection is a 2-week course of high-dose corticosteroids combined with albendazole, which reduces symptom duration and severity while managing the inflammatory response that causes neurological damage. 1, 2
First-Line Treatment Regimen
Corticosteroids for 2 weeks are the cornerstone of therapy, with strong evidence showing they shorten the duration and severity of symptoms by controlling the inflammatory response in the central nervous system. 2
Albendazole should be added to corticosteroids based on evidence that the combination provides better outcomes than either agent alone, particularly in severe infections with high parasite burden. 3, 2, 4
The recent 2025 outbreak cases in Brazil successfully used albendazole combined with ivermectin and corticosteroids for 2 weeks, with both patients achieving complete neurological recovery and normal CSF parameters within 2 weeks. 3
Gabapentin should be added for management of neuropathic pain, which is a prominent and debilitating symptom in many patients. 3
Dosing Specifics
Albendazole 400 mg orally is the standard dose, though the exact duration (single dose vs. 2 weeks) varies by severity. 1, 3
Ivermectin 200 mcg/kg as a single oral dose can be added to the regimen, particularly in severe cases, based on recent clinical experience. 5, 3
High-dose corticosteroids (typically prednisolone) for 14 days, with the exact dose tailored to severity of meningitis. 2
Diagnostic Confirmation
The diagnosis requires recognizing the clinical triad: neurological syndrome with headache/neck stiffness/paresthesia, eosinophils in CSF or blood (typically 27-35% in CSF), and exposure history to raw/undercooked snails, slugs, or contaminated produce. 3, 2
Real-time PCR detection of parasite DNA in CSF provides definitive confirmation when available. 1
Serologic testing by ELISA and Western blot on CSF can confirm diagnosis. 3
MRI may show subtle leptomeningeal enhancement but is not always positive. 3
Critical Clinical Considerations
The therapeutic strategy should be tailored to illness severity: mild infections with low CSF eosinophil counts may respond to anti-inflammatory therapy alone, while severe infections require combined anthelmintic and anti-inflammatory treatment. 4
Anthelmintic agents have shown limited efficacy in some studies, with one review stating they "have not shown efficacy in human infection," emphasizing supportive care with inflammation and intracranial pressure management. 6
However, more recent evidence from 2021 and 2025 supports albendazole use, particularly when combined with corticosteroids, representing an evolution in treatment approach. 1, 3
Common Pitfalls to Avoid
Do not delay corticosteroid therapy while awaiting diagnostic confirmation if clinical suspicion is high, as early treatment is more effective than later intervention. 2, 7
Obtain culturally sensitive exposure history, particularly regarding ritual ingestion of slugs in religious ceremonies, which may not be volunteered without appropriate questioning. 3
Do not dismiss the diagnosis when initial presentations mimic other conditions (UTI, gout) that fail to explain the full neurological picture. 3
Monitor for long-term sequelae as some patients develop persistent neurological symptoms requiring extended follow-up. 1