Brain-Invading Parasite May Have Spread Due To Climate Change And Globalization


Local health officials on the Hawaiian island of Maui are concerned about the potential spread of rat lungworm, an infection caused by a rare parasitic worm Angiostrongylus cantonensis.

Symptoms Of Rat Lungworm Infection

The parasite can live in the body for months and cause permanent damage as it can invade the brain and its membrane.

Symptoms of infection include sensitivity to light, neck stiffness, bad headache, and vomiting, which can start more than six weeks after the worm was ingested.

Those who catch the infection by eating contaminated fruits and vegetables and raw or undercooked snails may develop meningitis. The infection can be fatal in some cases.

"If you could imagine, it's like having a slow-moving bullet go through your brain," said epidemiologist Sarah Park, of the Hawaii department of health."There's no rhyme or reason why it's going to hang out in this part of the brain or that part of the brain." 

Snails And Slugs Can Pass The Parasite To Humans

The parasite thrives in the blood vessels of rats' lung but their larvae can be expelled in the droppings and then get eaten by slugs, snails, and other animals that can pass the young parasitic worms to humans.

Increase In Number Of Cases

At least six cases of the parasitic infection have been reported in Hawaii over the past three months, a significant increase from only two cases that were reported over the previous decade.

Difficult To Diagnose And Treat

The disease has no treatment and can be difficult to diagnose because no blood test is available to confirm infection.

Infectious disease specialist Constantine Tsigrelis, of the University Hospitals Cleveland Medical Center, said that treatment is complicated since the anti-parasitic drug that can kill the worm can also injure the patient's brain or nervous system. Giving this to patients can, therefore, worsen their condition.

Factors Behind Spread Of Parasite

Globalization and climate change appear to contribute to the spread of the parasite and the disease.

The first known case of rat lungworm was identified in Taiwan in 1944. Over the past years, the parasite has spread to other parts of the globe including the United States. Just like a number of other pathogens, the parasite is believed to have been brought and spread by rats in cargo ships.

"So it's a worm infection introduced into North America through globalization," said Peter Hotez, the National School of Tropical Medicine dean at Baylor College of Medicine. "Some suggest that it's due to snails or slugs in the ship ballasts-ships coming from Asia and going through the Panama Canal."

The brain-invading parasite is prevalent in tropical regions such as Southeast Asia and tropical Pacific islands but its geographical distribution has expanded in recent years. Experts fear that this could be one of the consequences of climate change as a warming world has been known to contribute to the spread of a range of diseases such as the mosquito-borne Zika virus.

"Most new infections seem to be caused by pathogens already present in the environment, which have been brought out of obscurity, or given selective advantage, by changing ecological or social conditions," reads a 2004 World Health Organization report.

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