Case Report: Gnathostomiasis Acquired in Costa Rica in a Returning Traveler to the United Kingdom.

Gnathostomiasis, caused by infection with nematode parasites in the genus Gnathostoma, is endemic in tropical and temperate zones, and is classically associated with East and Southeast Asia and, more recently, Latin America and Africa. We report a case of gnathostomiasis acquired in Costa Rica, which has not previously been considered an endemic country. The patient had eosinophilia with migratory myalgia, and the diagnosis was made after serological testing. Full resolution of symptoms and eosinophilia followed treatment with ivermectin and albendazole. The diagnosis can be challenging to make because of variability in presentation, lack of access to diagnostics, and emerging knowledge of endemic areas. Increased awareness of this disease among clinicians is vital for faster diagnosis and better outcomes in afflicted patients.