The Dreaded Rat Lungworm Found to be Rapidly Spreading in Southeast US
A recent study conducted by researchers at the University of Georgia College of Veterinary Medicine suggests that the rat lungworm, a parasite known for its ability to invade human brains, has firmly established itself in the Southeast US and is expected to continue its rapid invasion. The study involved small-scale surveillance of dead rats in the Atlanta zoo over a three-year period, from 2019 to 2022. Out of the 33 rats collected during this time, seven (21 percent) were found to have evidence of a rat lungworm infection.
The infected rats were discovered at different times throughout the study, with one infection in 2019, three in 2021, and three in 2022. This indicates sustained transmission of the parasite. The study’s authors concluded that the zoonotic parasite has been introduced to and has become established in a new area of the southeastern United States. The findings are concerning due to the severe infection that the rat lungworm, scientifically known as Angiostrongylus cantonensis, can cause in humans.
The life cycle of the rat lungworm begins in rats, where adult worms live in the arteries around the lungs. The worms mate and lay eggs, and the larvae are then expelled from the rat’s lungs through coughing. These larvae are then ingested by slugs or snails, either through the consumption of rat feces or through direct penetration of their bodies. The larvae develop in the slugs or snails and are eventually eaten by rats, where they migrate to the central nervous system and brain to become adult worms and complete the cycle.
Humans can become accidental hosts of the rat lungworm through various means. They may eat undercooked snails or accidentally ingest infected slugs or snails present in unwashed salads. Additionally, other animals can consume the infected gastropods, such as frogs, prawns, shrimp, or freshwater crabs, and if humans eat those animals without fully cooking them, they can become infected.
When the rat lungworm infects a human, it migrates to the central nervous system and brain, causing severe neurological dysfunction. Symptoms can range from mild headache, light sensitivity, and insomnia to more severe effects such as neck stiffness and pain, tingling or burning of the skin, double vision, bowel or bladder difficulties, seizures, and even paralysis, coma, and death in severe cases.
There is currently no specific treatment for a rat lungworm infection. Supportive treatment, pain medications, and steroids are typically the only options available. Anti-parasitic drugs have not proven to be effective and may worsen symptoms by triggering immune responses to dying worms.
The sustained presence of the rat lungworm in the Southeast US is alarming, as prevention and control efforts are crucial to mitigate the spread of the parasite. While previous cases of rat lungworm infections have been sporadic and limited to certain areas, this study shows the parasite’s establishment in a new region. Rat lungworm has also been reported in various territories globally, including Africa, the Caribbean, and North America. In 2017, Hawaii experienced a surge in human infections, with 18 confirmed and three probable cases.
As the rat lungworm continues to spread, researchers and medical practitioners are sounding the alarm for increased awareness and surveillance. They emphasize the need for medical professionals in affected regions to be familiar with the parasite and its potential consequences. More research, genetic analysis, and modeling are also crucial in mitigating the risk of infection to humans and other animals.