In a world-first discovery, a live worm has been found in the brain of a living human. The worm, of size 8 centimetres, was pulled out alive from the brain of an Australian woman, according to the Centers for Disease Control and Prevention (CDC). The woman, 64, complained of depression and forgetfulness before the parasite was pulled out of her brain.
She was admitted to a local hospital in southeast New South Wales, Australia, in late January 2021, because she suffered from abdominal pain and diarrhoea for three weeks, and subsequently a constant dry cough, night sweats, and fever.
Her symptoms escalated to depression and forgetfulness by 2022, the CDC said. This is when she was sent to a hospital in Canberra, where an MRI (magnetic resonance imaging) scan of her brain showed that the organ had some abnormalities which demanded surgery.
However, to the surprise of Dr Hari Priya Bandi, the woman's neurosurgeon, a long parasitic roundworm was found in the brain. Dr Sanjaya Senanayake, an infectious disease physician at the hospital, said that the neurosurgeon had never expected to find a "wiggling worm" in the patient's brain, a Guardian report said.
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A team at the hospital started investigating what kind of worm it was, and searched through textbooks to understand different types of roundworms and the neurological diseases they can cause, but to no avail.
After seeking help from experts outside the hospital, the doctors found that the parasite was Ophidascaris robertsi, a nematode or roundworm usually found in carpet pythons.
Lake areas inhabited by carpet pythons are the natural habit of Ophidascaris robertsi. While the patient had no direct snake contact, she used to collect native grasses from the lake, according to the CDC.
The doctors and scientists investigating this case believe that an infected python might have excreted the parasite, following which the larval eggs mixed with the grass. When the woman touched this grass, the eggs may have been transferred to the utensils she used for cooking or eating.
According to the CDC, adult Ophidascaris robertsi parasites live in the oesophagus and stomach of carpet pythons, and shed their eggs through faeces.
When small mammals ingest these eggs, larvae are formed in their bodies. In this way, they serve as intermediate hosts. In certain mammals, especially marsupials, parasitic larvae might migrate to thoracic and abdominal organs. There, the larvae may grow to a size of seven to eight centimetres.
When pythons consume these intermediate hosts, the life cycle concludes.
If humans are infected with Ophidascaris robertsi, they are considered accidental hosts. The Australian woman is the first human to be infected with this nematode.
There is a possibility that parasitic larvae have entered other body parts such as the liver, Senanayake said. However, a carefully curated treatment is being given because this is a first-of-its-kind case, and wrong medications may trigger inflammation in the brain.
While the patient is under constant supervision and is recovering well, she suffered from a pre-existing medical condition because of which she was immunocompromised. This could be the reason why the larvae manifested in her body.
After the larvae were removed from the woman's brain, she was given anthelmintics and dexamethasone to kill potential larvae in other organs. Anthelmintics are anti-parasitic drugs which help expel parasitic worms from the body, and Dexamethasone is an anti-inflammatory drug.
The CDC said that the case highlights the prevailing risk for zoonotic diseases because humans and animals interact closely.