Angiostrongyliasis is an infection by roundworms in the genus Angiostrongylus. The most common human illness is caused by A. cantonensis (often called rat lungworm) and mainly affects the brain and spinal cord, leading to eosinophilic meningitis. A less common form, caused by A. costaricensis, affects the intestines and abdominal blood vessels and may mimic appendicitis. People get infected by eating raw or undercooked snails or slugs, or from unwashed raw produce contaminated by tiny snails/slugs or their slime; you cannot catch it from another person. Most infections improve over time as the parasite dies; care focuses on symptoms and complications. CDC+1
Angiostrongyliasis is a disease caused by tiny roundworms (parasites) that normally live in rats. Humans get infected by swallowing the baby worms (larvae) that are hiding in snails, slugs, or foods contaminated with parts of these animals. In people, the worms cannot grow into adults. They often travel to the brain or the belly and then die there, which triggers swelling and inflammation. When the brain and the covering of the brain get inflamed, it is called eosinophilic meningitis. When the belly and intestines are inflamed, it is called abdominal angiostrongyliasis. CDC+3CDC+3CDC+3
Other names
Angiostrongyliasis is also called rat lungworm disease. When the nervous system is involved, doctors often say neuroangiostrongyliasis or eosinophilic meningitis due to Angiostrongylus cantonensis. When the intestines and abdomen are involved, it may be called abdominal or intestinal angiostrongyliasis and is usually due to Angiostrongylus costaricensis. Eye involvement is sometimes called ocular angiostrongyliasis. CDC+2CDC+2
Types
Neural (brain and nerves) angiostrongyliasis – Most often caused by A. cantonensis. It typically leads to eosinophilic meningitis with severe headache, neck stiffness, and abnormal skin sensations. Ocular disease can rarely occur when larvae reach the eye. CDC+1
Abdominal (intestinal) angiostrongyliasis – Usually caused by A. costaricensis. It inflames the intestine (often near the appendix) and nearby arteries, so it can mimic appendicitis or other surgical belly problems. CDC
Causes
Think of “causes” here as the specific ways exposure happens. Humans are accidental hosts; we do not spread it to other people. CDC
Eating raw or undercooked snails that carry the larvae. This is the most common route in many places. CDC
Eating raw or undercooked slugs, which can be heavily infected. Some children have swallowed them “on a dare.” CDC
Accidentally eating tiny snail/slug pieces stuck to raw produce (e.g., leafy greens, herbs) that was not washed well. CDC
Drinking or blending raw vegetable juices/smoothies containing undetected snail or slug parts. CDC
Eating raw or undercooked freshwater shrimp/prawns that acted as transport (paratenic) hosts. CDC
Eating raw or undercooked land crabs that carried larvae as transport hosts. CDC
Eating raw or undercooked frogs that carried larvae as transport hosts. CDC
Handling snails or slugs and then touching the mouth without washing hands, which can move larvae into the mouth. CDC
Contamination during food preparation (for example, chopping vegetables with a tiny hidden slug). CDC
Eating raw produce in areas where the parasite is common (travel-related risk if produce is not well washed). CDC
Local spread by invasive snails such as the giant African land snail (Achatina fulica), which can carry the parasite. CDC
Local spread by the semi-slug Parmarion martensi, an efficient carrier reported in parts of Hawaiʻi. CDC
Environmental introduction via rats on ships, which helps the parasite reach new regions. CDC
Contamination from slug slime on foods has been discussed; whether slime alone commonly transmits infection remains uncertain. CDC
Eating undercooked snails/slugs in traditional dishes or cultural practices that use raw mollusks. CDC
Food outbreaks linked to contaminated vegetables or juices in endemic areas. CDC
Abdominal infection from A. costaricensis after ingesting slugs or foods contaminated with their tissue/slime. CDC
Travel to endemic tropical or subtropical regions followed by risky food choices (raw produce, raw mollusks). CDC
Inadequate produce washing at home or in restaurants, allowing tiny mollusk parts to remain. CDC
Household gardens attracting snails/slugs to leafy greens (risk rises without careful washing and pest control).
Symptoms
Symptoms vary by species and body site. Many people recover, but severe cases can occur. CDC
Severe, global headache—the most common complaint in eosinophilic meningitis. PMC+1
Neck stiffness due to irritation of the meninges. CDC
Nausea and vomiting from meningeal irritation and raised pressure. CDC
Abnormal skin sensations (tingling, painful sensitivity) from nerve inflammation. CDC
Low-grade fever with general malaise. CDC
Photophobia or eye pain; rarely the parasite reaches the eye and causes inflammation. CDC
Radicular pain or limb weakness when spinal nerve roots are irritated (radiculitis). PMC
Cranial nerve problems (for example, facial weakness or double vision) in some patients. PMC
Ataxia or unsteady walk in severe nervous system involvement. PMC
Confusion or rare coma in severe encephalitis. PMC
Abdominal pain, often in the right lower belly, more typical with A. costaricensis. CDC
Fever with belly tenderness that can look like appendicitis (abdominal type). CDC
Nausea and vomiting from intestinal inflammation in abdominal disease. CDC
Bowel obstruction or bleeding—uncommon but reported in abdominal angiostrongyliasis. CDC
Prolonged recovery—brain symptoms may last weeks to months even without active worms. CDC
Diagnostic tests
A) Physical examination
General neurologic exam – Doctors look for meningitis signs, abnormal sensation, weakness, and cranial nerve problems that fit eosinophilic meningitis caused by A. cantonensis. This exam guides the next tests. CDC+1
Vital signs check – Fever and severe pain support an inflammatory process. Persistent vomiting or severe headache raises concern for meningitis. CDC
Eye examination – Rarely, a worm reaches the eye causing uveitis or vision loss; an exam can detect inflammation or visible parasites. CDC
Abdominal exam – Right-lower-quadrant pain, guarding, or rebound may mimic appendicitis in A. costaricensis infection. CDC
B) Manual bedside tests
Neck flexion tests (Kernig/Brudzinski signs) – Gentle maneuvers stretch the meninges; pain or resistance supports meningitis but is not specific. These signs help decide on lumbar puncture. CDC
Straight-leg raise – Shooting leg pain with raising the leg can reflect radiculitis when spinal roots are inflamed. It is supportive in neuro-cases with nerve-root pain. PMC
Focused cranial nerve testing – Checking eye movements, facial muscles, and swallowing can reveal nerve involvement seen in some patients. PMC
Targeted abdominal maneuvers (McBurney, Rovsing, psoas, obturator) – These simple bedside checks help judge appendiceal irritation in suspected abdominal angiostrongyliasis (often indistinguishable from appendicitis clinically). CDC
C) Laboratory & pathological tests
Complete blood count (CBC) – Many patients show eosinophilia in blood, which raises suspicion for a parasitic infection. CDC
Lumbar puncture (CSF analysis) – The key test for suspected eosinophilic meningitis. CSF eosinophilia (≥10% of CSF white cells or ≥10 eosinophils/µL) strongly supports the diagnosis when exposure risk is present. Opening pressure and protein are often high. CDC+2PMC+2
Real-time PCR for A. cantonensis on CSF (CDC) – A specific molecular test that can detect parasite DNA in CSF; available through reference labs/CDC. CDC
CSF cell count trend on repeat taps – Eosinophils can be absent early and appear later; repeated CSF can clarify evolving cases. CDC
Histopathology of intestinal tissue (biopsy or surgical specimen) – The definitive test for A. costaricensis is finding eggs/larvae/adult worms in intestinal tissue. Stool tests are usually negative. CDC
Conventional PCR with sequencing on tissue – Can confirm A. costaricensis in histologic samples when morphology is unclear. CDC
Serology/antibody tests (research or limited availability) – There is no widely available blood test for either species; limited assays exist in some settings, so clinicians rely on exposure history, eosinophilia, and CSF findings. CDC
D) Electrodiagnostic tests
Nerve conduction studies and EMG – Not required for diagnosis, but can document radiculopathy or neuropathy in severe neuro-cases with root pain or weakness. PMC+1
EEG (electroencephalogram) – Rarely used; may help if seizures or encephalopathy are suspected in severe brain involvement. (Supportive only; diagnosis depends on CSF and exposure.) PMC
E) Imaging tests
MRI brain (± spine) with contrast – Can show linear leptomeningeal enhancement or multiple small enhancing nodules; findings support inflammation from migrating larvae but are not specific. PubMed+1
CT head – Often normal or nonspecific; useful if MRI is not available or to rule out other urgent causes of headache. (Imaging complements, but does not replace, CSF analysis.) PMC
Abdominal ultrasound or CT – Helps evaluate appendicitis-like illness in A. costaricensis, showing bowel wall thickening or complications that point to surgical evaluation and tissue diagnosis. CDC
Non-pharmacological treatments
Note: These are supportive options your clinical team may combine with medicines. They do not kill the parasite; they help you feel better and lower risks while your immune system clears the infection.
Serial lumbar punctures (LPs): Repeatedly removing small amounts of spinal fluid to lower pressure and reduce severe headache in eosinophilic meningitis. Purpose: Headache relief and protection from pressure-related complications. Mechanism: Immediately reduces intracranial pressure and inflammatory mediators in CSF. PMC+1
Rest in a low-stimulus environment: Quiet, dark room, limited screen time. Purpose: Lessens headache triggers and nausea. Mechanism: Reduces sensory input that can aggravate meningitis headaches and photophobia. CDC
Hydration & balanced electrolytes: Small, frequent fluids; oral rehydration if vomiting. Purpose: Prevent dehydration and help medication tolerability. Mechanism: Supports perfusion and reduces secondary headache from dehydration. CDC
Cool or warm compresses to head/neck: Purpose: Comfort for headache and neck stiffness. Mechanism: Alters local blood flow and muscle tone to ease discomfort. (Supportive, low-risk home measure aligned with conservative care.) CDC
Gentle neck range-of-motion & posture coaching (guided by clinician): Purpose: Reduce stiffness from guarding. Mechanism: Low-intensity movement decreases muscle spasm without straining meninges. NCBI
Graded activity plan: Start very light daily walking and slowly build up as headaches improve. Purpose: Prevent deconditioning and support recovery. Mechanism: Gradual autonomic reconditioning without provoking headache. CDC
Sleep hygiene (regular schedule, cool dark room): Purpose: Improves pain tolerance and immune function. Mechanism: Normalizes sleep architecture, which modulates pain pathways. CDC
Trigger tracking (headache diary): Purpose: Identify activities/foods that worsen symptoms. Mechanism: Empowers pacing and avoidance of individualized triggers. CDC
Nausea control strategies (small bland meals, ginger tea if approved): Purpose: Reduce vomiting and dehydration. Mechanism: Gentle gastric stimulation and smaller gastric loads decrease nausea. CDC
Food safety counseling (during recovery and for household): Purpose: Prevent reinfection and protect family. Mechanism: Proper washing/cooking removes or kills larvae on produce or snail/slug tissue. CDC
(Further non-drug options your team may suggest include mindfulness breathing for pain coping, bowel rest/low-residue diet during acute abdominal inflammation, and community rodent/snail control. These are ancillary and individualized.) Merck Manuals
Drug treatments
Important: Doses below are typical examples for adults; real-world dosing is individualized by clinicians based on weight, severity, comorbidities, and local guidance.
Prednisone / Prednisolone (corticosteroid).
Class: Glucocorticoid. Typical dose/time: Often ~60 mg daily (or ~1 mg/kg/day) for ~14 days, then taper. Purpose: Reduce meningitis-related inflammation and headache. Mechanism: Dampens eosinophilic/Th2 inflammation around dying larvae. Side effects: Mood change, high sugar, gastric irritation, insomnia; taper to avoid rebound. RCTs and reviews show steroids shorten headache duration. ScienceDirect+1Dexamethasone (IV/PO corticosteroid).
Class: Glucocorticoid. Use: Moderate–severe cases or when IV route preferred. Purpose/mechanism: Same as above; higher anti-inflammatory potency. Side effects: Similar steroid risks. KargerAlbendazole.
Class: Benzimidazole anthelmintic. Typical dose/time: 400 mg twice daily for 14 days (often with a steroid). Purpose: May reduce duration of headaches by killing larvae earlier in disease. Mechanism: Inhibits microtubules in parasites; co-steroids blunt inflammatory reactions to dying worms. Side effects: GI upset, liver enzyme elevation; rare marrow effects—monitor. Evidence is mixed: one RCT showed shorter headache duration; another RCT found no added benefit over steroids alone; systematic reviews highlight variability but frequent reported benefit when combined with steroids. PubMed+2PubMed+2Mebendazole.
Class: Benzimidazole anthelmintic. Use: Alternative to albendazole for A. cantonensis in some settings (often with steroids). Caution: Not recommended for A. costaricensis abdominal disease. Side effects: GI upset; rare liver enzyme rise. CDCAcetaminophen (paracetamol).
Class: Analgesic/antipyretic (non-opioid). Dose: Per local max (e.g., ≤3–4 g/day in adults). Purpose: Headache and fever relief. Mechanism: Central prostaglandin modulation. Side effects: Liver risk with overdose or in liver disease. (Symptomatic care is standard.) CDCNSAIDs (e.g., ibuprofen, naproxen).
Class: Non-steroidal anti-inflammatory. Use: Alternative/adjunct for pain (avoid if GI bleeding risk from abdominal disease). Side effects: Stomach/bleeding risk, kidney effects. Merck ManualsOpioids (short-term, severe pain only).
Class: Opioid analgesic. Use: Rescue for refractory severe headache under close supervision. Risks: Sedation, constipation, dependence. (Reserve for brief, monitored use.) NCBIGabapentin / Pregabalin.
Class: Neuropathic pain modulators. Use: Tingling, shooting pains, dysesthesias. Mechanism: Modulates calcium channels in pain pathways. Side effects: Drowsiness, dizziness. (Used symptomatically.) NCBIAmitriptyline (low-dose at night).
Class: Tricyclic antidepressant for neuropathic pain/headache prevention. Side effects: Dry mouth, sleepiness; avoid in certain heart conditions. (Adjunctive, individualized.) NCBIOndansetron / other antiemetics.
Class: 5-HT3 antagonist. Use: Nausea/vomiting to maintain hydration and oral therapy. Side effects: Constipation, QT-prolongation caution. NCBIProton-pump inhibitor (e.g., omeprazole) with steroids/NSAIDs.
Class: Acid suppression. Purpose: Gastroprotection during anti-inflammatory therapy. Side effects: Headache, GI changes. NCBIAcetazolamide (specialist decision).
Class: Carbonic anhydrase inhibitor. Use: Selected cases with raised intracranial pressure when LPs insufficient. Mechanism: Lowers CSF production. Side effects: Paresthesias, metabolic acidosis; avoid in sulfonamide allergy. (Limited data—neurology guidance required.) NCBI
Key caution for A. costaricensis abdominal disease: anthelmintics are not advised; manage supportively and surgically if complications occur. Merck Manuals+1
Dietary molecular supplements
There are no supplements proven to treat angiostrongyliasis. Some general headache or recovery supports (e.g., adequate hydration; balanced diet; avoiding alcohol during steroid therapy) are reasonable, but supplements should not replace medical care. If you consider magnesium, riboflavin, or ginger for headache/nausea, discuss dosing and interactions with your clinician; these target symptoms, not the parasite. Public-health and clinical guidance emphasize supportive care, steroids, LPs, and case-by-case anthelmintics—not supplements. CDC+1
Immunity booster / regenerative / stem-cell drugs
There are no approved immune-boosting, regenerative, or stem-cell drugs for angiostrongyliasis. Using such products outside clinical trials is not recommended and may be harmful or delay effective care. Focus on proven supportive measures and clinician-directed therapies. CDC
When surgery is considered (
Surgery is not part of routine care for A. cantonensis meningitis. In A. costaricensis abdominal angiostrongyliasis, surgeons may operate only for complications such as appendicitis-like inflammation, bowel ischemia, obstruction, perforation, or uncontrolled bleeding. Typical procedures include appendectomy, segmental bowel resection, or exploratory laparoscopy/laparotomy when the diagnosis is uncertain but the abdomen is acute. Anthelmintics are avoided in this form. Merck Manuals+1
Prevention
Do not eat raw/undercooked snails or slugs.
Wash raw vegetables and herbs thoroughly; rinse under running water and inspect for tiny snails/slugs.
Peel or cook produce from gardens in endemic areas.
Control rats in and around the home and garden.
Keep slugs/snails out of kitchens; store produce away from pests.
Use gloves when gardening; wash hands after.
Rinse rain-harvested produce and clean catchment systems.
Teach children not to play with or taste snails/slugs.
Do not eat raw frogs, monitor lizards, or crustaceans that may carry larvae.
Follow local public-health alerts in endemic regions. CDC
What to eat and what to avoid
Eat: small, bland, easy-to-digest meals (rice, bananas, toast, soups), lean proteins, cooked vegetables, and plenty of fluids. This supports hydration and helps you keep medicines down. Avoid: alcohol (especially with steroids or acetaminophen), very spicy/fatty meals that worsen nausea, and—critically—any raw/undercooked snails/slugs or unwashed raw produce from endemic areas. Resume a normal balanced diet as symptoms improve. CDC+1
When to see a doctor urgently
Severe, persistent headache; neck stiffness; fever; vomiting; tingling or painful skin; confusion; new weakness; vision change.
Worsening abdominal pain (especially right-lower-quadrant), vomiting blood, black stools, or signs of intestinal blockage.
Recent travel/residence in an endemic area plus any suggestive symptoms—even if you’re unsure what you ate. Early supportive care helps. CDC
FAQs
How do people get it? By eating raw/undercooked snails/slugs or unwashed raw produce contaminated with them. Not spread person-to-person. CDC
What is eosinophilic meningitis? Inflammation of the brain/spinal cord linings with many eosinophils; a hallmark of A. cantonensis infection. CDC
Will I get better? Most people recover as the parasite dies; symptoms can last weeks to months. CDC
Do antiparasitic drugs cure it? They may help in some A. cantonensis cases (often with steroids), but evidence is mixed; not used for A. costaricensis. PubMed+2PubMed+2
Why are steroids used? To reduce inflammation that causes pain and neurological symptoms. ScienceDirect
Why do doctors do repeat lumbar punctures? To lower spinal fluid pressure and relieve severe headache. PMC+1
Can children get it? Yes; prevention and supportive care principles are similar—follow pediatric dosing and specialist guidance. CDC
Is there a vaccine? No. Prevention relies on food safety and pest control. CDC
Should I take supplements? No supplement treats this infection; discuss any with your clinician if used for symptom relief. CDC
Can CT/MRI diagnose it? Imaging helps exclude other problems; diagnosis relies on history, eosinophilia, and specialized tests. CDC
Do I need surgery? Only in abdominal disease with complications like appendicitis-like inflammation or obstruction. Merck Manuals
Can I swim in streams? Water isn’t the usual source; eating contaminated raw foods is the main risk—still avoid swallowing untreated water and wash produce. CDC
Do pets get it? Yes; consult a veterinarian for local risk and pet safety. (Human prevention steps still apply at home.) CDC
What if I’m pregnant? See a clinician early; management is individualized to balance maternal symptom control and fetal safety. NCBI
How can communities reduce cases? Public education, produce-washing campaigns, and rodent/snail control programs. CDC
Disclaimer: Each person’s journey is unique, treatment plan, life style, food habit, hormonal condition, immune system, chronic disease condition, geological location, weather and previous medical history is also unique. So always seek the best advice from a qualified medical professional or health care provider before trying any treatments to ensure to find out the best plan for you. This guide is for general information and educational purposes only. Regular check-ups and awareness can help to manage and prevent complications associated with these diseases conditions. If you or someone are suffering from this disease condition bookmark this website or share with someone who might find it useful! Boost your knowledge and stay ahead in your health journey. We always try to ensure that the content is regularly updated to reflect the latest medical research and treatment options. Thank you for giving your valuable time to read the article.
The article is written by Team RxHarun and reviewed by the Rx Editorial Board Members
Last Updated: September 17, 2025.
