Table of Contents
- Key Points
- Case Presentation
- Medical History and Travel Background
- Hospital Examination Findings
- Diagnostic Test Results
- Differential Diagnosis Considerations
- Final Diagnosis: Angiostrongyliasis
- Clinical Implications for Patients
- Study Limitations
- Patient Recommendations
- Frequently Asked Questions
- Source Information
Key Points
- Eosinophilic meningitis is defined by ≥10 eosinophils/μL or >10% eosinophils in CSF.
- Angiostrongylus cantonensis is the most common cause worldwide, transmitted via infected snails or slugs.
- Symptoms include headache, dysesthesia, allodynia, and can progress to confusion.
- Travel history to endemic areas like Southeast Asia and Hawaii is critical for diagnosis.
- Diagnosis requires lumbar puncture; treatment is supportive as no specific antiparasitic is proven effective.
Case Presentation
A 30-year-old woman was admitted to Massachusetts General Hospital with headache and dysesthesia (abnormal burning sensations). Her symptoms began 8 days earlier with a burning sensation in her feet that progressed to involve her legs over the next 2 days. The sensations worsened with light touch, a condition known as allodynia.
Ibuprofen treatment provided no relief. The patient experienced concurrent fatigue, which she initially attributed to jet lag after returning from a 3-week trip that included travel to Thailand, Japan, and Hawaii.
Five days before admission, she visited another hospital's emergency department where her vital signs were stable: temperature 37.2°C, blood pressure 120/60 mm Hg, pulse 106 beats/minute, respiratory rate 18 breaths/minute, and oxygen saturation 100%. Initial blood tests showed normal renal function, electrolytes, glucose, and creatine kinase levels. Notably, her white blood cell count was 8,680/μL (reference range 3,900-11,000) with an elevated eosinophil count of 870/μL (reference range 0-450).
Three days before admission, her sensory symptoms progressed to involve her trunk and arms, and she developed headaches. She measured a fever of 38.3°C at home two days before admission. One day before admission, a second emergency department visit showed persistent eosinophilia (1,050/μL) and mild metabolic acidosis.
Medical History and Travel Background
The patient had a medical history of irritable bowel syndrome and was taking dicyclomine and linaclotide. She lived in coastal New England, worked in an office setting, and had no tobacco, alcohol, or illicit drug use.
Her recent travel history was significant: she had returned 12 days earlier from a 3-week trip that included:
- Bangkok, Thailand: toured the city and ate various street foods (no raw food)
- Tokyo, Japan: spent most time in hotels and ate several sushi meals
- Hawaii: swam in the ocean multiple times and frequently ate salad and sushi
Hospital Examination Findings
On admission to Massachusetts General Hospital, her vital signs showed: temperature 37.3°C, blood pressure 131/96 mm Hg, pulse 62 beats/minute, respiratory rate 24 breaths/minute, and oxygen saturation 93%. She was alert but disoriented, appearing restless with inconsistent answers to questions.
Notable examination findings included a supple neck with normal motion and no rash present. Her body mass index was 26.3. She received intramuscular lorazepam and intravenous fluids upon admission.
Diagnostic Test Results
Initial laboratory studies showed progressive changes:
- White blood cell count increased from 8,680/μL to 15,500/μL over 5 days
- Eosinophil count initially elevated at 870/μL (reference 0-450) but dropped to 10/μL on admission
- Lymphocytes decreased from 1,880/μL to 1,100/μL
- Platelet count increased from 348,000/μL to 471,000/μL
Head CT showed no acute intracranial abnormalities. Microscopic examination of blood smears showed no parasites.
Cerebrospinal Fluid Analysis: Lumbar puncture revealed an opening pressure of 25 cm of water (reference range 10-25). The CSF showed:
- 694 white cells/μL (reference range 0-5)
- Differential: 81% lymphocytes, 9% monocytes, 8% eosinophils, 2% neutrophils
- Glucose: 36 mg/dL (2.0 mmol/L; reference 40-70 mg/dL)
- Total protein: 101 mg/dL (reference 15-45 mg/dL)
- Gram stain: many white cells, no bacteria
This finding met criteria for eosinophilic meningitis, defined as ≥10 eosinophils/μL of CSF or eosinophils accounting for >10% of CSF leukocytes.
Differential Diagnosis Considerations
The medical team considered multiple conditions that could explain both the neurological symptoms and eosinophilia:
Guillain-Barré Syndrome: This autoimmune nerve condition typically involves both sensory and motor symptoms with hyporeflexia. The patient's initially normal examination made this less likely, though purely sensory Guillain-Barré has been reported rarely.
Medication-Induced Meningitis: Ibuprofen can cause aseptic meningitis, but symptoms typically appear within 24 hours of ingestion (not 8 days later). Drug-induced meningitis usually shows neutrophilic predominance in CSF, not eosinophilic.
Eosinophilic Granulomatosis with Polyangiitis (EGPA): This autoimmune condition can cause eosinophilia and sensory symptoms mimicking Guillain-Barré, but the absence of purpuric lesions or sinusitis made this unlikely.
Infectious Causes: Given her travel history, several parasitic infections were considered:
- Gnathostomiasis: Caused by eating raw fish, endemic to Southeast/East Asia, but typically causes migratory radicular pain and cutaneous swelling
- Paragonimiasis: From eating raw crab, but usually causes gastrointestinal symptoms and cough
- Sparganosis: From consuming raw snakes, frogs, or freshwater fish, which she denied
- Strongyloidiasis: From contaminated water, but typically causes cutaneous manifestations
- Schistosomiasis: Nearly eradicated in Thailand and Japan, and she lacked characteristic symptoms
Final Diagnosis: Angiostrongyliasis
The patient was diagnosed with angiostrongyliasis, caused by the nematode Angiostrongylus cantonensis. This is the most common cause of eosinophilic meningitis worldwide.
Transmission: Infection occurs through:
- Eating raw or undercooked infected snails or slugs
- Consuming produce contaminated by infected snails/slugs or their slime
- Eating infected paratenic hosts (land crabs, freshwater prawns, frogs) that consumed infected snails
Geographic Distribution: Originally described in Taiwan, now found in tropical/subtropical regions including Southeast Asia, Pacific Islands (including Hawaii), and increasingly in Australia, Europe, southern United States, and the Caribbean.
Incubation and Pathophysiology: The average incubation period is 1-2 weeks. Larvae migrate to the central nervous system via bloodstream, appearing in the brain within hours of ingestion. Within 2 weeks, larvae reach the subarachnoid space, provoking severe inflammatory responses primarily involving eosinophils.
Hawaii reported only 5 confirmed cases in 2024, but with 9-10 million annual tourists, many infections may manifest after travelers return home.
Clinical Implications for Patients
This case illustrates several important clinical considerations for patients with neurological symptoms after travel:
Eosinophilic meningitis should be considered in patients with headache, sensory symptoms, and eosinophilia, especially with recent travel to endemic areas. The condition requires lumbar puncture for definitive diagnosis, which carries minimal risks (5-10% chance of headache, very rare serious complications).
Travel history is critical in diagnostic evaluation. Patients should provide detailed information about:
- Specific countries and regions visited
- Food consumption habits while traveling
- Water exposure activities
- Timing of symptom onset relative to travel
The progression from peripheral sensory symptoms to central nervous system involvement (headache, confusion) is characteristic of parasitic migrations in angiostrongyliasis.
Study Limitations
This case report has several limitations that patients should understand:
As a single case report, the findings represent one patient's experience and may not generalize to all cases of eosinophilic meningitis. The diagnosis was based on clinical presentation and travel history rather than definitive parasite identification in CSF or tissue.
The patient took zolpidem before developing confusion, which could have contributed to her mental status changes independent of the infection. Some laboratory values (particularly the drop in eosinophil count on admission) were unusual for typical parasitic infections and may reflect disease variability or measurement timing.
Patient Recommendations
Based on this case, patients should consider the following recommendations:
-
Travel Precautions: When visiting tropical or subtropical regions, avoid consuming:
- Raw or undercooked snails, slugs, or freshwater seafood
- Unwashed produce that may be contaminated with snail/slug slime
- Raw freshwater crabs, prawns, or frogs
-
Symptom Awareness: Seek medical attention if you develop:
- Unexplained burning or tingling sensations after travel
- Progressive headaches with fever
- Mental status changes after international travel
-
Medical Communication: When seeking care:
- Provide detailed travel history including destinations and dates
- Describe all foods consumed during travel
- Mention any water exposure activities
- Diagnostic Understanding: Be aware that lumbar puncture may be necessary for diagnosis and has minimal risks when performed appropriately
Frequently Asked Questions
What are the symptoms of eosinophilic meningitis?
Symptoms include headache, abnormal burning sensations (dysesthesia), and allodynia (pain from light touch). These often start in the feet and progress upward. Patients may also experience fatigue, fever, and confusion. The condition typically develops 1-2 weeks after exposure to the parasite.
How do you get eosinophilic meningitis from travel?
Infection occurs by eating raw or undercooked snails or slugs, or produce contaminated by their slime. Paratenic hosts like land crabs, freshwater prawns, or frogs can also transmit the parasite. Travel to endemic areas such as Southeast Asia, Pacific Islands, or Hawaii increases risk.
Why does eosinophilic meningitis come back after treatment?
The article does not describe treatment failure or recurrence. It notes that diagnosis is based on clinical presentation and travel history, and that the condition is managed supportively. No specific antiparasitic treatment is mentioned, so persistence may relate to the natural course of infection.
What is eosinophilic meningitis and how is it diagnosed?
Eosinophilic meningitis is inflammation of the membranes around the brain and spinal cord, with a high number of eosinophils in the cerebrospinal fluid. It is diagnosed by a lumbar puncture, which shows at least 10 eosinophils per microliter or eosinophils making up more than 10% of white blood cells in the fluid.
What causes eosinophilic meningitis after travel?
A common cause is infection with the parasite Angiostrongylus cantonensis, which is acquired by eating raw or undercooked infected snails or slugs, or produce contaminated by their slime. It is found in tropical and subtropical regions, including Southeast Asia, Pacific Islands like Hawaii, and increasingly in other areas.
What are the early symptoms of eosinophilic meningitis?
Early symptoms often include headache, abnormal burning sensations (dysesthesia), and fatigue. The burning may start in the feet and spread upward, and can worsen with light touch. Fever and confusion may develop later. These symptoms typically appear one to two weeks after exposure to the parasite.
Can eosinophilic meningitis be prevented during travel?
Yes, prevention involves avoiding raw or undercooked snails, slugs, freshwater seafood, and unwashed produce that may be contaminated with snail or slug slime. Also avoid raw freshwater crabs, prawns, or frogs. These precautions are especially important in tropical and subtropical regions.
Source Information
Original Article Title: Case 5-2025: A 30-Year-Old Woman with Headache and Dysesthesia
Authors: Joseph Zunt, MD, MPH; Amy K. Barczak, MD; Daniel Y. Chang, MD, PhD; Dennis C. Sgroi, MD; Eric S. Rosenberg, MD; David M. Dudzinski, MD; and colleagues
Publication: The New England Journal of Medicine, February 13, 2025; 392:699-709
DOI: 10.1056/NEJMcpc2412514
This patient-friendly article is based on peer-reviewed research from Massachusetts General Hospital case records.
