Parasitic Brain Worm Spreading Across Southeastern U.S., Scientists Warn

A parasitic brain worm that can be ingested through contaminated produce is making its way across southeastern America, scientists have warned.

Rat lungworm, Angiostrongylus cantonensis, is an invasive parasite that is spread through eating contaminated food, including fresh produce and escargots. It is typically found in Southeast Asia and the Pacific Islands, including Hawaii, but has more recently been identified in Texas, Louisiana, Alabama and Florida. Now, researchers have confirmed cases of the parasite in Atlanta, Georgia, raising concerns about its spread through the United States.

While the parasite cannot reproduce inside humans, it can still cause severe symptoms in rare cases.

"When the infective stage of the worm is accidentally ingested by a human, it can go to the brain or spinal cord and cause tremendous inflammation, leading to symptoms like nausea, vomiting, neck stiffness, headaches, sometimes arm and leg tingling," Nicole Gottdenker, a Professor of Pathology at the University of Georgia College of Veterinary Medicine, told Newsweek.

In rare severe cases, infection can lead to coma and even death, according to the Centers for Disease Control and Prevention. It is also possible for individuals to experience no symptoms for the first few weeks of infection, followed by neurological symptoms later down the line.

The parasite has a complex life cycle that involves transmission through several different animal hosts. As the name suggests, the eggs of the lungworm hatch in the lungs of rats. As the larvae develop, they are shed by rats in their feces and eaten by gastropods like slugs and snails. The larvae continue to develop in the gastropod until they reach what is known as the infective third-larval stage. At this point, the gastropods may be eaten by a rat, and the cycle begins again.

However, at this last stage, the gastropod might be eaten by another animal or may spread its parasites onto fresh produce. This is how the parasite ends up in humans, where they migrate to our brains, and occasionally our eyes or lungs.

In most cases, Gottdenker said the symptoms last for between two and eight weeks, although they can last much longer. Children may be particularly vulnerable, experiencing more pronounced fevers, irritability, drowsiness and lethargy, stomach problems and muscle twitching.

The parasite is thought to spread via infected rats on cargo ships, so testing rat populations can be a useful tool for monitoring its spread. In a recent study, published in the journal Emerging Infectious Diseases, Gottdenker and a team of researchers from Texas A&M, Zoo Atlanta and Mississippi State University collected tissue samples from 33 wild brown rats found dead on the grounds of a zoological facility in Atlanta from between 2019 and 2022.

After analyzing these samples, seven of the rats appeared to have worm-like larvae in their tissues, four of which were confirmed as rat lungworm. The other three also looked like they could have been rat lungworm but there was not enough genetic evidence to confirm their identity.

While this is a fairly small number of confirmed cases, the study demonstrates that the parasite is present in wild populations of rats in Atlanta posing a potential threat to human health.

"This is the first report in Georgia, and according to our cases analyzed here, the parasite has been in Atlanta since at least 2019," Gottdenker said.

"We need to understand more about the ecology of the parasite as it spreads and how it interacts with people, domestic animals, animals in captivity, and wildlife to further understand public health implications. Also, it is critical to understand the ways in which climate change and human land use (e.g. urbanization) can influence the spread of this parasite."

The parasite can also cause fatal infections in pets, birds and other wild animals.

"We need to work with our local communities in collaboration with scientists, public health, the medical establishment, and veterinarians in a 'one health' approach to better understand the risks to people and animals posed by this parasite, and to better prevent infection," Gottdenker said.

However, Gottdenker said there are certain precautions you can take to keep yourself and your family safe.

"People can avoid infection by washing vegetables thoroughly, not eating raw or undercooked snails or slugs, crabs, freshwater shrimp, or frog legs—and wear gloves if handling snails or slugs. And, as always 'wash your veggies' and 'wash your hands!'"