This Halloween, get ready to be frightened by an invisible terror lurking within her own mind as we share real-life horror stories.

On an ordinary day at Canberra Hospital, Australia, the infectious diseases physician, Dr Sanjaya Senanayake, was pulled into a medical mystery when a fellow neurosurgeon, Dr. Hari Priya Bandi, urgently whispered “You won’t believe what I’ve found in this lady’s brain- it is alive and its writhing”. Dr. Hari Priya Bandi extracted a nightmarish 8cm-long parasitic roundworm from her patient’s brain.

The World-First Discovery of Parasite in a Woman’s Brain

In late 2021, a 64-year-old woman from New South Wales found herself tangled in a horror tale. She was admitted to hospital after suffering from agonising abdominal pain and diarrhoea for three weeks. As if a victim of a malevolent curse, she soon started getting relentless dry cough, fever and night sweats that haunted her waking hours.

By 2022, her condition had worsened, as she started showing symptoms of memory loss and depression. Desperate for alleviation of these symptoms, a referral led her to Canberra Hospital where an MRI scan of her brain unveiled a parasite in her brain.

“But the neurosurgeon ventured into the MRI with no inkling that a terror awaited” Senanayake said. “Neurosurgeons often grapple with infections in the brain; however, this was something else… a discovery that defied a lifetime of expectations, something never seen before.”

Figure 1. Third stage larvae form of Ophidascaris robertsi (80mm long, 1mm diameter) (left), and MRI scan of O. robertsi larvae found in a woman's brain in Canberra Hospital (right). (Canberra Health)

The discovery of the parasite in the woman’s brain (Figure 1) prompted the hospital’s team to come together urgently . Their goal was to identify the type of roundworm causing the problem and decide the best treatment for the patient.

According to Dr. Senanayake, “We found ourselves in a perplexing situation” Senanayake explained, “We delved deep into the medical textbooks, scouring pages for clues among all the types of roundworms that could inflict these symptoms and invade the brain”. Despite their efforts, they couldn’t find the answer and had no choice but to seek help from external experts.

Dr. Senanayake explained, “In our small corner of Canberra, where surprises are few and far between, we turned into a specialist who dwelled in the realm of parasites”. They handed over the worm specimen to a CSIRO scientist who was experience in dealing with medical oddities and parasites.

His response was astonishing. He examined the “creature” and exclaimed “Oh my goodness, this is Ophidascaris robertsi!”. This revelation felt like an unexpected Halloween treat, uncovering a twist to this medical mystery.

Exploring Ophidascaris Robertsi

Ophidascaris robertsi is a type of nematode, commonly known as roundworms. These roundworms follow a complicated life cycle. Specifically, Ophidacaris robertsi is found in Australia, where carpet pythons (Figure 2) are their main hosts.

Carpet Python host of Ophidacaris Robertsi
Figure 2. Carpet Python, the usual definitive host of Ophidacaris robertsi. (Wikipedia)

Adult roundworms live in the oesophagus and stomach inside the phytons, laying their eggs in the snake’s faeces. These eggs, which can cause infestation, are then consumed by various small mammals, serving as intermediate hosts. In these intermediate hosts, the roundworm larvae settle and can even migrate to their thoracic and abdominal organs. Surprisingly, the third-stage larvae can grow up to 70-80mm in length. The cycle repeats when the pythons consume the small animals infected with Ophidascaris robertsi, as shown in Figure 3.

Life Cycle of Roundworms
Figure 3. Figurative representation showing the life cycle of Roundworms. (Worm Boss)


In this unique case, Ophidascaris robertsi had made its way into new territory by invading a human – marking the first instance of this parasite being found in humans. The patient lived near a lakeside region frequented by carpet pythons. While she had no direct contact with these pythons, she often collected vegetation from her yard, including greens from near the lake for cooking. The doctors’ theory was that the python might have left parasite eggs in the grass through its faeces. Then, the woman could’ve contracted the parasite by touching the grass, possibly transferring the larvae’s eggs to food or kitchen utensils, or by eating the greens collected from the yard.

Dr. Senanayake stressed the importance of complete care for the patient. Because this parasite had never before been found in humans, the medical team moved cautiously to make sure nothing was overlooked.

Ophidascaris Robertsi 8cm worm from womans brain
Figure 4- Live larvae found in woman’s brain, size approximately of 80mm. (Emerging Infections Diseases CDC)

Preventing Brain Parasites

It is essential to note that 75% of emerging infections worldwide come from animals and can be transmitted to humans, known as zoonotic diseases, similar to coronavirus. Thankfully, this parasite infection can’t spread from person to person, so there is no risk of a pandemic like COVID-19 or Ebola. Still, we should take precautions. You can prevent it by washing food, cooking it thoroughly, and wearing protective clothing in wildlife areas.

Indeed, while this medical journey may have started with spine-tingling discoveries and unexpected twists, it ends on a positive note. The brave woman has received complete treatment and is on the path to recovery. In the books of medical history, she will always be remembered as the first person in the world to confront a brain parasite straight out of a nightmare and emerge victorious.






Hossain, M et al. (2023). Human Neural Larva Migrans Caused by Ophidascaris robertsi Ascarid. Emerging Infectious Diseases, 29(9), 1900-1903. https://doi.org/10.3201/eid2909.230351.

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