Snake-Adapted Roundworm Found Burrowing Through Woman’s Brain in Australia
A 64-year-old woman from southeastern New South Wales, Australia, had quite the shock when a neurosurgeon pulled a wriggling 3-inch roundworm from her brain. The discovery came after over a year of misdiagnosis and confusion for the woman, who had been experiencing recurring and varied symptoms.
The extracted worm was unlike any previously identified as causing human infection, making it difficult for doctors and infectious disease experts to pinpoint the cause of the woman’s illness. Upon closer examination, it was revealed that the roundworm was typically found in snakes, specifically carpet pythons indigenous to the area where the woman lived. This infection marks the first reported case of a human with this particular snake-adapted worm and the first time the worm has been discovered burrowing through a mammalian brain.
The case was reported in the latest issue of Emerging Infectious Diseases and began in January 2021 when the woman sought treatment at a local hospital. She presented with symptoms such as abdominal pain, diarrhea, dry cough, and night sweats. Initial tests indicated an infection, and scans revealed pneumonia in her lungs, as well as lesions in her spleen and liver. However, tests for known microorganisms, parasites, cancers, and autoimmune diseases all came back negative, leaving her with an unexplained case of pneumonia. She was prescribed prednisolone, a corticosteroid, to alleviate her symptoms.
Three weeks later, the woman was admitted to another hospital due to recurring fever and persistent cough. Once again, doctors found signs of infection in her lung, liver, and spleen, and her blood test showed high levels of eosinophils—a type of white blood cell associated with fighting parasitic infections. In response to concerns of a false-negative for a human roundworm infection, doctors treated her with ivermectin, an anti-parasitic drug.
From mid-2021 to early 2022, the woman’s liver and lungs improved. By also adding another drug to help manage her eosinophil counts, the woman was able to reduce the dosage of prednisolone.
However, her condition took a turn for the worse when she experienced a three-month period of forgetfulness and worsening depression. Brain magnetic resonance imaging revealed a growing lesion in her right frontal lobe. In June 2022, she underwent a biopsy, during which the neurosurgeon extracted the live, writhing parasite from her brain.
Further examination confirmed the roundworm as Ophidascaris robertsi based on its red color and morphological features. Genetic testing later confirmed the identification.
Treatment for the infection involved another round of ivermectin and albendazole, another anti-parasitic drug. While the woman’s lung and liver lesions improved over months, her neuropsychiatric symptoms persisted but were mitigated.
It is believed that the woman became infected while foraging for warrigal greens, also known as New Zealand spinach, near a lake close to her home that was inhabited by carpet pythons. Typically, adult O. robertsi reside in the snakes’ esophagus and stomach, releasing eggs in the snakes’ feces. The eggs are then picked up by small mammals that the snakes prey upon. The larvae develop and establish themselves in the small mammals, growing to a significant length despite the animals’ small size. The worm’s life cycle is completed when the snake consumes the infected prey.
Doctors hypothesize that the woman inadvertently ingested the eggs, either by not properly washing or cooking the greens, or by neglecting to thoroughly wash her hands and kitchen equipment. In hindsight, the progression of her symptoms suggests an initial foodborne infection, followed by the migration of worm larvae from her gastrointestinal tract to various organs. The administration of prednisolone, an immunosuppressive drug, may have unintentionally aided the worm’s migration into the central nervous system.
As a result of this case, Karina Kennedy, a professor at the Australian National University (ANU) Medical School, and Director of Clinical Microbiology at Canberra Hospital, stresses the importance of thoroughly washing any foraged or garden-procured foods. She also emphasizes the significance of practicing proper kitchen safety and hand hygiene.
For now, the woman continues to be monitored, with doctors applauding her patience and resilience throughout the process. Sanjaya Senanayake, an infectious disease specialist at ANU and Canberra Hospital, expressed admiration for the woman, stating, “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.”