Worms and larvae: insects that like to settle in our heads

An Australian woman recently had a three-inch roundworm removed from her brain. It was a first. No specimen of the species Ophidascaris robertsi has ever been discovered in a human.

On the other hand, it happens again and again that living animals settle in the human head. And these can sometimes be larger than just three inches.

A Chinese man living in England complained of headaches, seizures and memory problems for years. The search for the cause was unsuccessful for four years. In 2014, doctors noted on MRI images that they had diagnosed a minor brain injury. The strange thing about it: it seemed to wander. In four years about five centimeters from the right to the left hemisphere.

The tissue samples that followed brought clarity: the “wound” was a larva of the rare Spirometra erinaceieuropaei. To develop into the terminal stage of 75 centimeters in length, this tapeworm needs at least three hosts, one of which can also be a human. However, human contamination is rare: only those who eat raw tadpoles or undercooked frogs or snakes can become infected. Treating open wounds with ointments made from frog or snake meat can also be contagious. According to research, these are mainly used in China.

Once in the human body, the parasite preferentially settles in the brain and spinal cord, in the breasts or abdomen. As a result, the described symptoms may occur, but also blindness and signs of paralysis. In some cases, the infection even ended fatally.

One from India from 2014 should be mentioned here as representative of a large number of myiasis cases. At the time, Dr. Meenesh Juvekar, a patient, said to be 45 or 55 years old, depending on the source, had 50 maggots from his nose. The parasites, up to an inch long, had already lodged deep in a sinus. There they slowly ate their way through flesh and bones towards the eye. Without treatment, there would have been a risk of blindness or even death.

The fly maggot disease myiasis is not uncommon in tropical regions in humans and animals. A fly lays its eggs not only in body openings, but also in open wounds or minor injuries. The special thing about the Jevekar case was that he published the endoscope recordings of the two-hour operation on YouTube. Although the video was later removed, Juvekar helped develop endoscopy videos. The mix of disgust and liberation that comes from watching these videos has a significant following, and endoscopy videos have established themselves as a genre in their own right.

Without tadpoles or toad meat, you can trap pork tapeworm larvae in your brain. Like Spirometra erinaceieuropaei, the pork tapeworm requires several hosts to fully develop. The bottom line: the parasite has no disadvantage if it massively damages or even kills the intermediate host. A dead intermediate host – such as a deer – is usually eaten in nature. The worm, nesting in dead flesh, easily finds its last host in this way. That people are therefore poorly suited as intermediate hosts may well be stupid worm don’t suspect it.

Humans usually ingest pork tapeworm eggs unnoticed through small amounts of infected faeces from a final host (pig, human). So-called oncospheres arise from the eggs in the intestine. These penetrate the intestinal wall, where they are distributed throughout the body via the bloodstream. They usually settle in the muscles, but the brain can be affected. This is called neurocysticercosis. At their destination, the oncospheres turn into larvae (called fins). If these die back after a while, the tissue around them can become calcified. These 1-2 centimeter “eggs” are easily recognizable on X-rays.

Neurocysticercosis is rare in Europe, but is the most common cause of structural epilepsy worldwide. Symptoms include seizures, blindness, increased intracranial pressure, paralysis, and cognitive impairment. However, neurocysticercosis can also be fatal.

More often than the eggs (through the feces), the fins (or cysticerci) are ingested through spoiled pork. If this is the case, the consumer becomes the definitive host, which is less dangerous.

In 2017, the “Welt” reported a rat worm infestation on the island of Maui in Hawaii. In ten years, 82 people became infected with the parasite. Some of them didn’t survive: “It was like someone suddenly stuck a long needle through a soft spot at the top of my head, then pushed it further down towards my left ear, then back up to my temple and then backwards behind my right eye.” , the newspaper quoted an affected person.

The larva of the rat lungworm also lodges in the human brain. Infection occurs through the consumption of a secondary host, for example a snail that resides on a lettuce leaf. Treacherous: Snail slime can also contain infectious larvae. If you wash the lettuce and catch the snail, but not all the remains of its trail, you can also become infected.

During its journey through the body, the loa loa lodges in the eye. Therefore, the threadworm is also called eyeworm or wandering filaria. Female specimens reach a body length of up to seven centimeters. Infections are most common in West and Central Africa.

A German tourist caught the worm in Sri Lanka in 2017 – one with the proud size of 10 centimeters. She complained to her doctor about an invisible foreign body in her eye. Only the examination at the eye clinic of the University of Munich revealed the intruder. After a small cut, the parasite could be removed from the patient’s eye with tweezers.

In 2018 and 2019, two cases in the US caused a stir. Within a short time, worms of the genus Thelazia gulosa settled in the eyes of two women. There they caused temporary conjunctivitis. In both cases, the patients were able to pull several worms out of their eyes themselves.

Thelazia gulosa usually only affects livestock. There they live on the tears of the animals.

The roundworm recently operated on an Australian patient was six centimeters long; the tapeworms removed from the heads of three different patients in China in 2017 and 2018 measured 10, 25 and even 30 centimeters in length. The cases are less well documented; details are only known of the first case.

The ten centimeter specimen had caused epileptic seizures in the 26-year-old affected person. Not without pride, doctors at the University Hospital in the southeastern Chinese city of Nanchang reported that the animal was still alive when it was removed: “The worm was completely white and could swim,” said treating physician Wang Chunliang of the South China Morning Post. .

So.

And now we wish you «En Guete!» and have a nice evening.