Rat Lungworm Threatens Human and Animal Health Worldwide

A recent study has raised concerns about the presence and potential spread of the rat lungworm parasite, Angiostrongylus cantonensis, in the Southeastern United States. This parasite, known for its affinity for rats and slugs, can occasionally infect humans and cause severe neurological symptoms. 

According to Ars Technica, the study was conducted by researchers at the University of Georgia College of Veterinary Medicine, focused on the surveillance of dead rats at the Atlanta Zoo.

Over the period from 2019 to 2022, the researchers discovered evidence of rat lungworm infection in seven out of 33 collected rats, indicating a 21 percent infection rate. Notably, these infections occurred at various times throughout the study, with cases in 2019, 2021, and 2022, suggesting ongoing transmission. 

The study’s authors concluded that this suggests the zoonotic parasite has been introduced to and has established itself in a new area of the Southeastern United States. This finding is concerning because rat lungworm infections in humans can have serious consequences. 

Rat lungworm typically resides in rats, where it follows a complex life cycle. Adult worms live in the rat’s lung arteries, lay eggs, and release larvae, which are then excreted in rat feces. These larvae can be ingested by slugs or snails, which in turn are eaten by rats, completing the cycle.

Humans can become accidental hosts by consuming undercooked snails or accidentally ingesting infected slugs or snails in salads or through contaminated food. Once in a human, the worm migrates to the central nervous system and brain, potentially causing severe neurological symptoms. 

While some believe the parasite cannot complete its life cycle in humans and eventually dies off, there is evidence of adult worms reaching human lungs. Unfortunately, there is no specific treatment for rat lungworm infections, making prevention and control crucial. 

This study’s findings are particularly alarming because although rat lungworm has been sporadically detected in the Southeastern US before, it had not been previously observed in Georgia rats. Cases had previously been reported in captive nonhuman primates in other Southern states. 

Rat lungworm’s global expansion is driven by factors such as climate change and the spread of its hosts, including rats and giant snails. It has now been found in parts of Africa, the Caribbean, North America, and even Europe. The parasite has caused infections in humans in 30 territories. 

Furthermore, researchers in Europe have raised concerns about the presence of rat lungworm in the continent. Until 2018, the parasite was not considered endemic to Europe. However, in that year, the worms were detected in hedgehogs on the Mediterranean island of Mallorca. Recently, researchers reported that rat lungworm has established a foothold in the city of Valencia on the Spanish mainland. 

The spread of rat lungworm in Europe is particularly worrisome because it could potentially extend to more temperate regions, mirroring what has already occurred in Australia and the United States. As climate change continues to alter environmental conditions, even more northern parts of Europe may become accessible to A. cantonensis, like what has been observed in China. 

Similarly, researchers in the Southern United States are sounding the alarm, emphasizing the need for healthcare professionals to be vigilant regarding rat lungworm infections. They are also advocating for increased surveillance, genetic analysis, and modeling to effectively mitigate the risk of infection for both humans and animals. 

In summary, the presence and potential spread of rat lungworm in new regions, including the Southeastern United States and Europe, pose significant public health challenges. Awareness, prevention, and control measures are crucial in addressing this emerging health threat. Researchers and medical practitioners are working diligently to better understand and combat this parasitic nematode to protect human and animal health. 

Journal References  

Mole B. (2023) “Worm that jumps from rats to slugs to human brains has invaded Southeast US” https://arstechnica.com/health/2023/09/worm-that-jumps-from-rats-to-slugs-to-human-brains-has-invaded-southeast-us/.