The patient: A 64-year-old woman in New South Wales, Australia
The symptoms: The woman was admitted to hospital after having abdominal pain and diarrhea for three weeks. She also had a persistent dry cough and night sweats.
What happened next: Three weeks later, the woman returned to the hospital with a cough and fever, despite still taking prednisolone, and the lesions on her organs had not healed.
Further tests failed to identify the cause of her breathing difficulties. Tissue cultures showed no evidence of bacterial or fungal infection. Blood work showed that her immune system was not producing antibodies against various parasitic flatworms, such as bloodworms (Schistosoma) or liver flues (Fasciola). There was also no evidence of these parasites in her stool samples.
The doctors advised the patient to continue taking prednisolone and also prescribed her ivermectin, a treatment for parasitic worms, since she had informed the doctors that she had traveled to countries where such parasites are common.
But her respiratory symptoms did not go away, and they got worse when she tried to reduce the prednisolone dose. Her condition continued unchanged for several months.
The diagnosis: About a year after her first hospital visit, the woman began to develop signs of depression and had episodes of forgetfulness. Doctors ordered an MRI of her brain and discovered a lesion on her right frontal lobe. They then performed an open biopsy to reveal and examine the damaged area. That’s when they discovered “a string-like structure” inside the lesion, which they identified as a live parasitic worm called a helminth, according to a report on her case.
The worm was bright red and measured about 80 millimeters long and 1 millimeter thick.
The treatment: The doctors removed the helminth from the woman’s frontal lobe and examined the surrounding tissue, where they found no more parasites. They gave her ivermectin for two days, this time in combination with a four-week course of albendazole, a broad-spectrum drug for treating helminth infections, to kill any lingering parasites in her organs.
Albendazole is absorbed by the central nervous system more quickly than ivermectin, and these drugs have previously been used together to treat nematode infections in humans and snakes. The patient also received a 10-week course of the corticosteroid dexamethasone, to prevent further inflammation.
Six months after the operation and three months after the end of the dexamethasone course, the lesions in the patient’s lungs and liver had disappeared, the white blood cell count was normal and the neuropsychiatric symptoms had improved.
What makes the case unique: Doctors identified the helminth as a third-stage larva of Ophidascaris robertsia type of parasitic nematode native to Australia. The adult worms reproduce inside the carpet python (Morelia spilota), but the nematode can infect other animals during the larval stages of its life cycle.
Carpet pythons were common near the woman’s lakeside home, and although she did not recall having any direct contact with snakes, she often foraged wild greens for cooking. She probably became infected after touching or eating plants contaminated by O. robertsi eggs, the case report authors suggested. After the eggs hatched, the larvae migrated to her organs.
The lifespan of this larval infection was not unusual, as laboratory rats can be hosts O. robertsi larvae for more than four years, according to the report. However, no human infection by this parasite had ever been documented, and the parasite’s larva had never been found in the brain of the host.
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This article is for informational purposes only and is not intended to provide medical advice.
Hossain, M., Kennedy, KJ, Wilson, HL, Spratt, D., Koehler, A., Gasser, RB…Senanayake, SN (2023). Human Neural Larva Migrans Caused by Ophidascaris robertsi Ascarid. New infectious diseases29(9), 1900-1903. https://doi.org/10.3201/eid2909.230351
