World-first parasitic infection: 3-inch roundworm found in woman’s brain
Researchers have discovered the world’s first case of a new human parasitic infection, pulling a live roundworm picked up from a carpet python from the brain of an Australian woman. They say the case highlights the risks posed by zoonotic diseases caused by pathogens that jump from animals to humans.
The researchers from the Australian National University (ANU) and Canberra Hospital say the 64-year-old woman picked up the Ophidascaris robertsi roundworm after collecting Warrigal greens, a spinach-like native plant, from a nearby lake inhabited by carpet pythons. She would collect the plant and use it in cooking.
The O. robertsi roundworm commonly lives in the esophagus and stomach of the carpet python and sheds its eggs via the snake’s feces. Despite having no direct contact with snakes, it’s thought the woman was infected with the parasite directly, either from touching the plant or inadvertently consuming its eggs.
“This is the first-ever human case of Ophidascaris to be described in the world,” said Sanjaya Senanayake, corresponding author of the study. “To our knowledge, this is also the first case to involve the brain of any mammalian species, human or otherwise.”
The woman was admitted to a local hospital in January 2021 after three weeks of abdominal pain, diarrhea, constant dry cough and night sweats.
“She initially developed abdominal pain and diarrhea, followed by fever, cough and shortness of breath,” said Karina Kennedy, one of the study’s co-authors. “In retrospect, these symptoms were likely due to migration of roundworm larvae from the bowel and into other organs, such as the liver and lungs. Respiratory samples and a lung biopsy were performed; however, no parasites were identified in these specimens.”
Of course, doctors weren’t looking for an infection like the one they eventually found.
“At that time, trying to identify the microscopic larvae, which had never previously been identified as causing a human infection, was a bit like trying to find a needle in a haystack,” Kennedy said.
In 2022, over the course of three months, the woman started experiencing forgetfulness and worsening depression. A brain MRI was performed, which showed a right frontal lobe lesion, and she underwent an open biopsy. It was then that the 3-inch (8-cm) roundworm was discovered and pulled, alive and wriggling, from the woman’s brain. Only one roundworm was found, whose identity was confirmed by parasitology experts.
After the worm was removed, the woman was treated with antiparasitic drugs and dexamethasone to address potential larvae in other organs, given that Ophidascaris larvae have been known to survive for lengthy periods – sometimes for more than four years – in animal hosts.
The researchers say the case highlights the potential risks posed by zoonotic diseases.
“There have been about 30 new infections in the world in the last 30 years,” said Senanayake. “Of the emerging infections globally, about 75% are zoonotic, meaning there has been transmission from the animal world to the human world.”
While this kind of infection can’t be passed from person to person, it still poses a potential problem.
“This Ophidascaris infection does not transmit between people, so it won’t cause a pandemic like SARS, COVID-19 or Ebola,” Senanayake said. “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.”
The researchers say the discovery highlights the importance of general food safety, particularly when foraging in a space shared by wildlife.
“People who garden or forage for food should wash their hands after gardening and touching foraged products,” said Kennedy. “Any food used for salads or cooking should also be thoroughly washed, and kitchen surfaces and cutting boards wiped down and cleaned after use.”
The woman continues to be monitored by a team of infectious disease and brain specialists.
“It is never easy or desirable to be the first patient in the world for anything,” said Senanayake. “I can’t state enough our admiration for this woman who has shown patience and courage through this process."
The study was published in the journal Emerging Infectious Diseases.