A Second Spanish Man's Brain 'Tumors' Were Tapeworm Larvae. He Had Never Left Spain.

Since our coverage of a similar Spanish case on June 27, 2026, a second detailed case report has surfaced in the same country with a nearly identical diagnostic arc, a different patient, and a transmission route that complicates the usual assumptions about who is at risk.

A 60-year-old man in Spain showed up complaining of a headache that had been building for two weeks. He also reported subtle behavioral changes. A neurological exam found mild movement delays. His blood work was largely normal, with one exception: elevated immunoglobulin E (IgE), a marker associated with allergic responses, autoimmune conditions, and parasitic infections.

A CT scan of his head showed multiple lesions scattered throughout the brain, accompanied by swelling. The clinical picture pointed almost entirely toward metastatic cancer.

The Cancer Hunt That Came Up Empty

Doctors placed him on a corticosteroid to control the headache-causing inflammation, which provided relief, then launched an extensive cancer search. That included a whole-body contrast-enhanced CT scan, a colonoscopy, and a hybrid PET/CT scan, which is one of the more sensitive tools available for mapping malignancy across the body. None of those tests found cancer.

A follow-up MRI of the brain resolved the mystery. Unlike the CT, the MRI had enough resolution to show the lesions were not tumors. They were cysticerci, encapsulated larvae of the pork tapeworm Taenia solium. The MRI could even resolve the scolexes, the worm heads, sitting inside the cysts, according to the case report in Emerging Infectious Diseases.

The Transmission Question

Taenia solium is not endemic to Spain. The man stated he had not traveled internationally. By the standard epidemiological checklist, he should not have had this infection.

His doctors traced a plausible, if speculative, exposure route through his occupational history. For years before retiring a decade ago, he worked in construction alongside migrants from regions where pork tapeworm is endemic. One of those coworkers, according to the case report, had a known tapeworm infection. The doctors speculated he may have been exposed through cryptic fecal-oral transmission: shared meals, shared bathrooms, contaminated surfaces.

Taenia solium spreads through two distinct pathways. Eating undercooked pork containing cysticerci leads to intestinal tapeworm infection in the person who ate it. That person then sheds eggs in their feces. If those eggs reach another person through poor hand hygiene, contaminated food, or water, that second person can develop neurocysticercosis, the larval form that migrates to the brain. The man in this case almost certainly ingested eggs, not cysts in meat.

What This Means for Non-Endemic Countries

From a public health standpoint, a fair concern is whether cases like this are being systematically undercounted in countries that don't screen for Taenia solium because it isn't considered a local disease. Neurocysticercosis mimics brain tumors on standard CT imaging well enough that it sends doctors down a cancer diagnostic path, as it did here. Without MRI follow-up, or without a clinician who thinks to test for parasites, patients in non-endemic countries could receive wrong diagnoses or delayed correct ones.

This concern has a counter-argument worth taking seriously. Spain's medical system caught this case. The doctors ran the right confirmatory imaging, published the result to alert other clinicians, and identified the likely transmission route. The system, in this instance, worked.

A separate question is how long diagnosis took and what it cost. The patient went through a full-body cancer workup, including a PET/CT scan, before the correct answer emerged. PET/CT scans are expensive, involve significant radiation exposure, and take time to schedule. If elevated IgE combined with multiple brain lesions in an immunocompetent patient with no systemic cancer findings were treated as a stronger trigger to test for parasites earlier in the workup, the path to diagnosis would be shorter.

Where the Science Currently Stands

Neurocysticercosis is the world's leading preventable cause of adult-onset epilepsy, according to the World Health Organization, and the majority of burden falls on low- and middle-income countries where Taenia solium circulates in pig populations with limited veterinary oversight. Cases in wealthy, non-endemic countries have historically been linked to international travel or immigration.

This case, and the one covered here on June 27, suggest that cryptic domestic transmission, meaning person-to-person spread without any travel link, is a real if rare occurrence. How rare is the unresolved question. The Emerging Infectious Diseases case report does not include seroprevalence data for Spain, and there is no national surveillance system tracking neurocysticercosis in most European countries because the disease is not considered endemic there.

The man in this case was treated with antiparasitic therapy. The report does not specify his outcome as of its publication date.