Snakes in a Brain: parasitic worm infects woman in world first

A 64-year-old woman from New South Wales has been declared the first carrier of a particular parasitic infection from a worm usually found in carpet pythons.

The gruesome discovery has been published in a new paper in the Emerging Infectious Diseases journal and makes for fascinating reading.

The larvae found in the woman’s brain was Ophidascaris robertsi, a roundworm common to carpet pythons. The worm lives in a python’s oesophagus and stomach, for part of its lifecycle, and sheds its eggs in the host’s faeces, which are then eaten by small mammals.

“This is the first-ever human case of Ophidascaris to be described in the world,” ANU and Canberra Hospital infectious disease expert and co-author of the study, Associate Professor Sanjaya Senanayake says.

“To our knowledge, this is also the first case to involve the brain of any mammalian species, human or otherwise.

“Normally the larvae are found in small mammals and marsupials, which are eaten by the python, allowing the life cycle to complete itself in the snake.” 

The woman was first known to researchers after she was admitted to hospital in January 2021. She was immune-suppressed due to a white blood cell disorder and was experiencing serious abdominal pain, diarrhea, a cough, and night sweats.

The doctors first diagnosed her with a type of pneumonia, but they couldn’t work out what caused it.

Three weeks later she was back in hospital with a fever and cough. A CT scan found unusual lesions in her liver, spleen and lungs.

While a myriad of tests were done – they found that bacterial and fungal cultures were negative. The team decided to treat her with ivermectin, just in case it could be from a parasitic worm.

By the middle of the year another scan found her lungs were improving, but her spleen was not.

It wasn’t until 2022 when the woman started experiencing forgetfulness and depression that scientists in Canberra checked her brain. Magnetic resonance imaging found a large lesion at the front of her brain, and in June, she underwent a biopsy to remove it.

What the researchers found was an 8-centimetre-long worm – still alive – wiggling out of her brain.

This wasn’t a typical human parasitic worm. In fact, this woman is the first known infection of this species in the world.

“It is never easy or desirable to be the first patient in the world for anything. I can’t state enough our admiration for this woman who has shown patience and courage through this process,” Senanayake said.

It is unknown how this happened, however the researchers have suggested that it could have been due to foraging a native grass called “Warrigal greens” near her house. If a python had shed the parasite via its faeces in the area, she might have been infected by eating or touching the grass.

“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,” Senanayake said.