His blood leukocyte count was 11.5 × 10⁹/L with 80% neutrophils, 12% lymphocytes, 4% monocytes, 2% basophils, and 2% eosinophils. Cerebrospinal fluid (CSF) analysis showed 320 cells/μL with 6.5% eosinophils (21 eosinophils/μL). Results of CSF testing by PCR for herpes simplex virus 1 (HSV-1) and HSV-2 DNA were negative, as were cultures for bacteria, mycobacteria, and fungi. Results of serum and CSF antibody tests for Borrelia burgdorferi, Treponema pallidum, HSV-1, HSV-2, tick-borne encephalitis virus, Toxoplasma gondii, Taenia solium, Toxocara spp., and Trichinella spp. were also negative. Results of stool examination for Ascaris lumbricoides, Trichuris trichiura, Taenia spp., Giardia intestinalis, Strongyloides spp., and Entamoeba histolytica were negative. The patient was also negative for HIV by ELISA. Magnetic resonance imaging scans of the brain and spine were unremarkable. A. cantonensis infection was diagnosed by immunoblot testing at the Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok. Antibodies against A. cantonensis 31-kDa antigen were detected in serum and CSF of the patient; antibodies against Gnathostoma spinigerum were not detected.

Treatment was symptomatic; to lessen the headache, 4 lumbar punctures were performed. After 1 month, the patient’s general condition was greatly improved; however, minor symptoms such as diminished concentration, slow thinking, and mild headache persisted. Urinary retention lasted for 38 days, and the patient had occasional mild headaches and paresthesia in his feet for the next 5 months.

Because large numbers of persons from Europe travel to destinations where angiostrongyliasis is endemic, it is somewhat surprising that the infection has been rarely described in Europe. In a Google and Medline Internet literature search, we identified 9 additional case reports and 1 report on a cluster of 5 A. cantonensis infections. The first report was in a 14-month-old child born in Tahiti who became ill in France in 1988 (1). Eight cases, as did our case, involved travelers returning to Europe after a visit to disease-endemic areas (2–9) (Table). Not all cases were serologically confirmed, most likely because antibody tests for A. cantonensis infection have not been widely available. In a retrospective cohort study, 5 French policemen, who returned from French Polynesia with severe headache and blood eosinophilia, were believed to have eosinophilic meningitis caused by A. cantonensis (10). However, CSF examination was performed in only 1 patient, and none of the cases were serologically confirmed.

Definitive diagnosis of angiostrongyliasis would require identification of larvae or young adults in human tissue, such as the brain, CSF, and eye chamber, which is rarely achieved. Thus, the diagnosis is usually made on the basis of serologic test results. Specific A. cantonensis antigens (29 kDa, 31 kDa, and 32 kDa) were identified; antibodies against these antigens can be detected by ELISA, dot-blot ELISA, or Western blot.

In most patients, A. cantonensis causes a benign and self-limiting disease; treatment is usually symptomatic. Data are limited, but mostly favorable, on the use of steroids, albendazole, and mebendazole. However, the administration of antihelmintics without steroids is not recommended because such treatment might elicit deleterious inflammatory responses to dying worms within the nervous system or ocular structures.

In summary, the presence of headache, fever, and paresthesias in travelers returning from disease-endemic areas should alert clinicians to the possibility of eosinophilic meningitis caused by A. cantonensis. With growing international travel, physicians may encounter A. cantonensis infection more frequently.