When a 64-year-old Australian woman was sent to hospital for brain surgery, neurosurgeon Dr. Hari Priya Bandi was not expecting to pull out a live 8-centimeter (3-inch) long parasitic roundworm that wriggled between her forceps.
“I’ve only come across worms using my not-so-good gardening skills … I find them terrifying and this is not something I deal with at all,” Bandi told CNN of the world’s first discovery of a live worm inside a human brain.
The finding unleashed a mad scramble to find out what exactly the parasite was, Canberra Hospital infectious disease expert Sanjaya Senanayake told CNN.
One colleague in the hospital lab was able to reach an animal parasitology expert at a governmental scientific research agency just 20 minutes away – and found their unexpected answer.
“We were able to send the live wiggling worm to him, and he was able to look at it and immediately identify it,” Senanayake said.
Molecular tests confirmed it was Ophidascaris robertsi, a roundworm usually found in pythons, according to a press release from the Australian National University and the Canberra Hospital.
“To our knowledge, this is also the first case to involve the brain of any mammalian species, human or otherwise,” said Senanayake, who is also a professor at Australian National University.
Researchers say the patient lived near a lake area inhabited by carpet pythons in southeastern New South Wales. Although she did not have direct contact with the reptiles, it’s likely she caught the roundworm after foraging Warrigal greens, a native leafy vegetable, which she cooked and ate.
The doctors and scientists involved in her case theorized that a carpet python might have spread the parasite via its feces into the greens, which the patient then touched and cross-contaminated with food or other cooking utensils.
How the worm was discovered
The woman was initially admitted to a local hospital in late January 2021 after suffering three weeks of abdominal pain and diarrhea, followed by a constant dry cough, fever and night sweats.
Several months later, her symptoms developed into forgetfulness and depression and she was sent to a hospital in the Australian capital, where an MRI scan revealed something unusual in the right frontal lobe of her brain.
What normally happens is that carpet pythons in Australia carry the Ophidascaris robertsi and shed parasite eggs in their feces, spreading through vegetation that small mammals and marsupials eat. At some point, pythons also eat those same infected animals, and the parasite then lives inside the snake, completing the cycle.
In this case, the patient was likely an accidental host of the worm, Senanayake said. The parasite is highly invasive and it is suspected that its larvae, or juveniles, were present in other organs in the woman’s body, including the lungs and liver.
Senanayake said the case highlighted the growing danger of diseases and infections passing from animals to humans, especially as people encroach deeper into animal’s habitats.
“There’s more opportunities for humans, domestic animals and wild animals to interact with each other and the vegetation that’s out there. So this is just another marker that more new infections will be seen in the future,” Senanayake said.
He said about 30 new infections had been uncovered in the world in the past three decades. And of those emerging infections, about 75% were zoonotic, meaning there has been transmission from the animal world to the human world – including coronaviruses.
“This Ophidascaris infection does not transmit between people, so it won’t cause a pandemic like SARS, COVID-19 or Ebola. However, the snake and parasite are found in other parts of the world, so it is likely that other cases will be recognized in coming years in other countries,” Senanayake said.
“The other message from this case is about foraging. People who forage should wash their hands after touching foraged products. Any foraged material used for salads or cooking should also be thoroughly washed.”
Other tapeworm larvae
This case in Australia is entirely different from recent reports of people developing painful headaches with tapeworm larvae found in their brain.
That condition is known as neurocysticercosis, which can cause neurological symptoms when larval cysts develop in the brain.
People are infected with the parasite after swallowing eggs found in the feces of a person who has an intestinal tapeworm, according to the US Centers for Disease Control and Prevention (CDC). More than 1,000 cases are reported every year in the US alone.
Last year, a study revealed that a 25-year-old woman in Australia was found to have tapeworm larvae in her brain after suffering from a headache that lasted for more than a week.
An MRI scan of her brain led doctors to believe a tumor might be the cause of her pain, but after operating and removing the lesion, they discovered it was actually a cyst full of tapeworm larvae.