Recent research suggests that the rat lungworm, a parasite capable of causing severe brain infections in both humans and animals, has firmly entrenched itself in the Southeast US. This alarming trend emphasizes the dangers of this zoonotic parasite as it continues its swift territorial expansion.
A joint study between the University of Georgia College of Veterinary Medicine and other institutions discovered the presence of rat lungworm (Angiostrongylus cantonensis) in brown rats near Atlanta. The research involved surveillance of dead rats found on the grounds of a zoological facility in Atlanta between 2019 and 2022. From the 33 rats studied:
- 7 rats (21%) tested positive for the worm.
- Infected rats were found across all years, denoting a sustained transmission. The full study can be found in this week’s edition of Emerging Infectious Diseases.
Understanding the lifecycle of the rat lungworm is crucial:
- Adult worms reside in the arteries surrounding a rat’s lungs, where they reproduce.
- Larvae emerge from the rat’s lungs, are coughed up, swallowed, and eventually excreted.
- Slugs and snails, either through consumption or invasion, pick up the larvae.
- The larvae mature within these gastropods.
- Ideally, rats consume these infected slugs or snails, ingesting the mature larvae.
- The ingested larvae penetrate the rat’s intestines, enter the bloodstream, migrate to the brain and nervous system, mature, and ultimately migrate back to the lungs to reproduce.
Transmission to Humans
Humans become accidental hosts primarily through the consumption of undercooked or contaminated food:
- Eating undercooked infected snails.
- Consuming an infected slug or snail in unwashed produce.
- Eating other animals like frogs, prawns, shrimp, or freshwater crabs, may have consumed infected gastropods.
Origins and Spread
Originally identified in Asia, the rat lungworm wasn’t native to the US. However, its presence has grown:
- First identified in Hawaii.
- Later found in Texas, Louisiana, Alabama, and Florida.
- Likely introduced by infected rats and snails via trade routes, like merchant ships.
Given its recent discovery in Georgia, it’s believed the parasite might have been present there even before the 2019 identification.
Impact on Humans and Animals
- The main concern for humans:
- The worm can cause meningoencephalitis – a severe inflammation of the brain and its surrounding membranes.
- For animals:
- Infections found in captive wildlife throughout the Southeast US.
- An instance of infection in a red kangaroo in Mississippi.
Reasons for Expansion
- Climate Change: Climate-induced changes might be introducing and supporting new snail species, which can carry the parasite.
- Human Interference: Human activity could be aiding the spread and establishment of the parasite in new areas.
Prevention and Public Awareness
The foremost step in addressing the rat lungworm’s proliferation is ramping up public awareness campaigns. Understanding the parasite’s transmission methods can drastically reduce human infections.
- Public Health Campaigns: These should be initiated to inform the public about the risks associated with consuming undercooked snails and freshwater creatures, as well as the importance of thoroughly washing produce.
- Education in Schools: Including modules about zoonotic parasites in school curriculums can ensure the younger generation is informed and cautious.
- Labeling and Information: Suppliers and restaurants should provide information on the origin of their seafood, especially snails and shrimp. Transparent supply chains can allow consumers to make informed choices.
Research and Surveillance
Continuous research and monitoring are crucial for tracking the parasite’s movement and evolution:
- Increased Surveillance: More comprehensive surveillance of wild rats and other potential carriers should be conducted across the US to track the parasite’s spread.
- Collaboration: Research institutions should collaborate on a national and international scale to compare data and strategize combat efforts.
- Funding: Governments and health organizations should prioritize funding studies about rat lungworms, aiding in the development of potential treatments and preventive measures.
Final Remarks and Precautions
This significant rise of rat lungworm in the Southeast US poses a genuine health threat to humans, domestic animals, free-ranging wildlife, and captive animals. Medical professionals and veterinarians must consider rat lungworm infection as a possible diagnosis for any cases of meningoencephalitis they come across. The continuous expansion of this parasite is a concerning factor for public health, and awareness and preventive measures need to be established promptly.