Rare Brain Worm Found in Woman’s Frontal Lobe – First Human Case

A rare and unsettling medical mystery unfolded in New South Wales, Australia, when doctors discovered a live parasitic worm in the brain of a 64-year-old woman. The case, detailed in a report published by the Centers for Disease Control and Prevention (CDC), marks the first documented human infection with Ophidascaris robertsi, a roundworm typically found in carpet pythons.

A Complex Path to Diagnosis

The woman initially presented with a cluster of symptoms – abdominal pain, diarrhea, a persistent dry cough, and night sweats – that prompted her admission to the hospital in early 2021. A CT scan revealed opaque areas in her lungs, indicative of inflammation or infection, alongside lesions in her liver and spleen. Initially diagnosed with eosinophilic pneumonia, a rare lung condition characterized by a high number of eosinophils (a type of white blood cell), she received a course of prednisolone, a steroid, which provided some temporary relief.

Although, her condition didn’t improve, and the lesions persisted. Further testing ruled out bacterial and fungal infections, and blood work showed no evidence of antibodies to common parasitic flatworms like Schistosoma or Fasciola. Despite the lack of clear evidence, doctors prescribed ivermectin, a medication used to treat parasitic worms, given the patient’s travel history to regions where such parasites are prevalent. Unfortunately, her respiratory symptoms continued, and attempts to reduce the prednisolone dosage worsened her condition. For months, the cause of her illness remained elusive.

Neuropsychiatric Symptoms and a Surprising Discovery

Around a year after her initial hospitalization, the woman began experiencing new symptoms: depression and forgetfulness. An MRI of her brain revealed a lesion on the right frontal lobe. A subsequent open biopsy, performed to examine the damaged tissue, revealed the astonishing source of her illness – a living, 3-inch-long parasitic worm. The worm, identified as a third-stage larva of Ophidascaris robertsi, was a bright red and thread-like in appearance.

Treatment and Recovery

Following the removal of the worm from her brain, the patient received a two-day course of ivermectin, combined with a four-week regimen of albendazole, a broad-spectrum anti-helminth drug. Albendazole is known to penetrate the central nervous system more effectively than ivermectin, and the combination has been used successfully in treating nematode infections in both humans and animals. She too received a 10-week course of dexamethasone, a corticosteroid, to manage inflammation.

Six months after surgery and three months after completing the dexamethasone course, the lesions in her lungs and liver had resolved, her white blood cell count returned to normal, and her neuropsychiatric symptoms significantly improved, demonstrating a remarkable recovery.

Understanding Ophidascaris robertsi and the Route of Infection

Ophidascaris robertsi is a parasitic nematode typically found in carpet pythons (Morelia spilota) in Australia. Adult worms reside in the snakes’ esophagus and trachea, reproducing and shedding eggs. While the parasite’s life cycle usually involves snakes, it can infect other animals during the larval stages. The CDC report suggests the woman likely became infected through contact with or ingestion of plants contaminated with O. Robertsi eggs. She frequently foraged for wild greens near her lakeside home, creating a potential exposure pathway.

The longevity of the larval infection is notable. laboratory rats can harbor O. Robertsi larvae for over four years. However, this case is unique given that it represents the first documented human infection with this parasite, and the first instance of the larva being found in a human brain. You can discover more information about parasitic infections from the CDC here: CDC Parasites Page.

Implications for Public Health and Future Surveillance

This case highlights the potential for zoonotic transmission – the spread of disease from animals to humans – of parasites. While the risk of O. Robertsi infection remains low, it underscores the importance of thorough washing of foraged foods and maintaining awareness of potential parasitic threats in areas where snakes are prevalent. South West Radiology, a leading medical imaging center in Sydney, offers CT scans which can help detect abnormalities in the abdomen and lungs, as described on their website: South West Radiology.

The discovery also prompts a re-evaluation of diagnostic approaches for unexplained neurological or respiratory symptoms, particularly in individuals with potential exposure to environmental sources of parasites. Abdominal CT scans, as described by SWSLHD, can visualize organs within the abdomen and may be useful in detecting parasitic infections: SWSLHD – Medical Imaging – Abdominal.

What comes next?

Public health officials are likely to enhance surveillance for O. Robertsi in both animal and human populations, particularly in regions where the parasite is endemic. Further research is needed to understand the full spectrum of potential human infections and to develop more effective diagnostic and treatment strategies. The Australian Prescriber notes that diagnostic imaging is often not needed in patients with chronic abdominal pain, but this case demonstrates the importance of considering unusual diagnoses: Imaging for chronic abdominal pain in adults.