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| Invasive Brain-Infesting Worm Found in Georgia |
A parasitic nematode with a penchant for infesting the brains of its hosts, primarily transmitted through rats and snails, is expanding its territory within the United States, as indicated by recent research findings. Scientists have now verified the presence of this parasitic organism, known as the rat lungworm (Angiostrongylus cantonensis), within local rodent populations in the state of Georgia. While human infections remain infrequent, this versatile parasite can also infiltrate and afflict various other animal hosts.
The name "rat lungworm" hints at the intricate life cycle of this parasite. Adult rat lungworms reside within the lungs of rats, where they reproduce and lay their eggs. These eggs develop into larvae, which are subsequently expelled into the rat's throat and re-ingested through the digestive tract, ultimately ending up in the rat's feces. Herein begins the parasite's journey, as a snail or slug either consumes the contaminated feces or comes into close contact with it, allowing the larvae to burrow into the mollusk. Once inside, the larvae continue to mature and enter their infectious stage.
In an ideal scenario, from the parasite's perspective, another rat consumes the infected snail, enabling the larvae to complete their life cycle by maturing within the rat's lungs and initiating the cycle anew. However, at times, humans or other animals inadvertently consume the infected snail or come into contact with the larvae in some other manner. In humans, this can lead to an invasive infection of the nervous system and brain known as eosinophilic meningitis. Additionally, fish, frogs, and crustaceans can serve as alternative but less favored hosts for the infectious larvae, potentially providing another route of transmission to humans.
Historically, most documented cases of human rat lungworm infections have been in Southeast Asia and the Pacific Islands, including the endemic presence of these parasites in Hawaii. In recent years, however, the rat lungworm has made appearances in other regions worldwide, including Louisiana, Texas, and Florida in the United States. The latest study, featured in the journal Emerging Infectious Diseases earlier this month, now presents clear evidence of their establishment in Georgia as well.
The research team conducted an analysis of tissue samples collected from brown rats discovered deceased around an Atlanta zoo between 2019 and 2022. Approximately 20% of these rats tested positive for rat lungworm infection, with confirmation through genetic testing and physical examination. Genetic analysis also revealed a striking similarity between these worms and those found in Louisiana and other parts of the U.S. where they have been recently documented.
The study's authors suggest that these findings "indicate that this zoonotic parasite has been introduced to and has successfully colonized a new region in the southeastern United States." There is also the possibility that the parasites have been present in Georgia for a longer duration than currently recognized, as other studies have reported infected rats in neighboring states like Florida and Alabama before 2019.
Although reported cases of human rat lungworm infections in the U.S. remain rare, it is plausible that their prevalence is underestimated. Most infections tend to be mild and often resolve without the need for treatment. However, in cases of severe infestation, permanent neurological damage or even fatality can occur. Moreover, these parasites pose a threat to the wildlife they infect within their expanding territory.
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