Did His Unusual Dinner Lead to a Tape Worm 50 Years Later?

During surgery to repair a hernia in a 71-year-old man’s right groin, his doctors discovered something unexpected: a tapeworm.

The surgeons fished the 10-inch long worm out carefully and recorded the extraction of this infection rarely seen in the peritoneal cavity. Even outside the body, the live worm could be seen undulating on the table.

Four years earlier, the same patient had a 7-inch tapeworm found incidentally and extracted during the repair of a left inguinal hernia, according to Chang-Seop Lee, MD, PhD, and Yeon Jun Jeong, MD, PhD, of Jeonbuk National University Medical School in Jeonju, South Korea.

The patient had not received antiparasitic medication afterwards. Prior to the surgery the patient reported no symptoms “other than a painless bulge in his right groin,” the group reported along with the image published in the New England Journal of Medicine.

“There was no localized pain, inflammatory reaction, or neurological symptoms suggestive of parasitic infection,” Lee and Jeong told MedPage Today.

Lab tests prior to the operation also found no eosinophilia that could have signaled a parasitic infection. A polymerase chain reaction (PCR) test classified the worm as Spirometra erinaceieuropaei, and the diagnosis of sparganosis was made.

Sparganosis can occur in humans who eat undercooked meat from infected snakes or frogs or drink water containing infected crustaceans. Its larvae can migrate to different tissues and remain viable for long periods, the authors noted.

Upon further questioning, the patient recalled eating raw snake meat on several occasions during his military service some 50 years prior, “based on the belief that it provided health benefits or increased stamina,” Lee and Jeong noted in an email.

The patient was given antiparasitic drugs and said he felt well 45 days after his surgery, the authors said.

This case “represents an exceptionally unusual clinical presentation and illustrates the prolonged survival and migratory potential of spargana in humans,” Lee and Jeong said.

Any case of sparganosis would represent an unusual infection, commented Bruce E. Hirsch, MD, of Northwell Health in Manhasset, New York. Only about 2,000 cases have been reported, mainly in Southeast Asia, although many more might go undiagnosed or unreported, he said.

The infection typically begins in cats and dogs, which pass eggs into the water that produce coccidia that are ingested by microscopic crustaceans or crayfish. Inside the crustaceans, the eggs develop into one kind of larva; after being ingested typically by frogs or snakes, spargana form another kind of larva. The cycle starts again when the infected frogs or snakes are eaten by cats and dogs, and very occasionally human beings, explained Hirsch.

In addition to eating infected critters or drinking water with “hatchlings,” sparganosis has been contracted by people who use frog tissue as poultices on wounds, Hirsch told MedPage Today. The infection can present clinically from weeks to decades after the initial exposure, he added.

Often the infection presents as a nodule that can become tender and inflamed, may bleed, and may proliferate with different types of tapeworms. In about 20% of cases, that nodule occurs in the brain or central nervous system, which can be very dangerous and occasionally fatal, Hirsch said.

However, in this case, the “happy tapeworm” was not causing the elderly patient any suffering, Hirsch said. “Not only does the tapeworm look extremely comfortable inside the peritoneal cavity, but the peritoneal cavity looks fine,” Hirsch said.

Some research does point to a more symbiotic relationship between humans and tapeworms, including a study suggesting benefits against certain auto-immune conditions. “The fact that this guy got along so well with sparganosis for over a half century, I think, is telling us that there’s nuances about the biology,” Hirsch said.

Thomas A. Moore, MD, of the University of Kansas School of Medicine-Wichita, noted that most sparganosis cases are discovered retrospectively after a nodule has been excised.

The only case he’s seen involved a 41-year old Missouri man who collected several frogs, dropped them in a pot of boiling water, and ate them, sharing them with children on his son’s camping trip. At least one frog was raw, Moore was told.

Two of the five children with him ingested one bite each. The man, who ate most of the frog meat, experienced fever, headache, loss of appetite, and eosinophilia, which subsided and was replaced with fatigue and muscle cramps for another week or two, according to Moore. The patient also complained of nodules under his skin, but Moore found none on exam.

The patient, a pilot, was reluctant to have any testing done that might affect his flight certification, and antibody tests are hard to come by for this infection, so the case was never confirmed. Asked what motivated the “frog eating party,” Moore said, “I think he was just trying to be the ‘cool dad.'”

As for any clinical lesson, Jeong and Lee said sparganosis, while rare, should be included in the differential diagnosis for patients who have consumed raw reptiles or amphibians in endemic regions, which include North America and Southeast Asia.

They also stressed that spargana may be discovered incidentally during unrelated surgeries and that “[c]areful inspection of unexpected intraoperative findings and appropriate pathological or molecular confirmation are important for establishing the diagnosis.”

Moore said doctors don’t typically ask, “‘Have you eaten some raw snakes or frogs?’ because it doesn’t come up.” But, he added, a good rule with any unusual illness is to ask not only “Where did you travel?” but also, “What did you eat?”

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