In a world first, scientists say that an 8cm (3in) worm has been found alive in the brain of an Australian woman.
The “string-like structure” was pulled from the England-born patient’s damaged frontal lobe tissue during surgery in Canberra last year.
The red parasite could have been there for up to two months.
Researchers are warning that the case highlights the increased danger of diseases and infections being passed from animals to people.
“Everyone [in] that operating theatre got the shock of their life when [the surgeon] took some forceps to pick up an abnormality and the abnormality turned out to be a wriggling, live 8cm light red worm,” said Sanjaya Senanayake, an infectious diseases doctor at Canberra Hospital.
“Even if you take away the yuck factor, this is a new infection never documented before in a human being.”
The Ophidascaris robertsi roundworm is common in carpet pythons – non-venomous snakes found across much of Australia.
Scientists say the woman most likely caught the roundworm after collecting a type of native grass, Warrigal greens, beside a lake near where she lived.
Writing in the journal Emerging Infectious Diseases, Mehrab Hossain, an Australian expert in parasitology, said he suspects she became an “accidental host” after using the foraged plants – contaminated by python faeces and parasite eggs – for cooking.
There began what doctors have called an “unusual constellation of symptoms” of stomach pain, a cough, night sweats and diarrhoea that escalated into increasing forgetfulness and worsening depression.
The patient was admitted to hospital in late January 2021. A scan later revealed “an atypical lesion within the right frontal lobe of the brain”. The cause of her condition was only revealed by a surgeon’s knife during a biopsy in June 2022.
She is recovering well despite making medical history.
“The invasion of the brain by Ophidascaris larvae had not been reported previously,” writes Dr Hossain. “The growth of the third-stage larva in the human host is notable, given that previous experimental studies have not demonstrated larval development in domesticated animals, such as sheep, dogs, and cats.”
Dr Senanayake – who is also an associate professor of medicine at the Australian National University (ANU) – told the BBC that the case is a warning.
The ANU team reports that 30 new types of infections have appeared in the last 30 years. Three-quarters are zoonotic – infectious diseases that have jumped from animals to humans.
“It just shows as a human population burgeons, we move closer and encroach on animal habitats. This is an issue we see again and again, whether it’s Nipah virus that’s gone from wild bats to domestic pigs and then into people, whether its a coronavirus like Sars or Mers that has jumped from bats into possibly a secondary animal and then into humans.”
“Even though Covid is now slowly petering away, it is really important for epidemiologists… and governments to make sure they’ve got good infectious diseases surveillance around.”
