A 60-year-old man in Castellón, Spain, sought emergency care after suffering two weeks of progressive headaches and behavioral changes. Physicians initially suspected metastatic brain cancer after CT scans revealed multiple abnormal spots resembling spreading tumors.
When whole-body scans failed to identify a primary cancer source, an MRI uncovered fluid-filled cysts containing the heads of tapeworms. A blood test confirmed neurocysticercosis, a central nervous system infection caused by the pork tapeworm, Taenia solium.
The patient had never traveled to regions where the parasite is endemic. Researchers theorize he accidentally ingested microscopic eggs years earlier while working a construction job with migrant coworkers from endemic areas. Transmission occurs by swallowing eggs through contaminated food or water, allowing larvae to travel to the brain.
The man was treated with antiparasitic drugs and corticosteroids, recovering fully without complications. Authors of the CDC journal report emphasized that missing a travel history should not rule out the diagnosis, even where metastatic cancer is statistically more likely. Less than 2% of U.S. cases are domestically acquired; only 18 locally acquired cases were identified in Western Europe between 1990 and 2011.