The Maui News

New research shows that rat lungworm disease can be transmitted by many more species than just slugs and snails, the primary species Hawaii officials warned of amid a spate of rat lungworm cases in recent years.

Researchers from the University of Hawaii at Manoa and the University of London in the U.K. combed through nearly 140 scientific studies published between 1962 and 2022 and found 32 species of freshwater prawns/shrimp, crayfish, crabs, flatworms, fish, sea snakes, frogs, toads, lizards, centipedes, cattle, pigs and snails can act as carriers of the rat lungworm parasite. Of these, at least 13 species of prawns/shrimp, crabs, flatworms, fish, frogs, toads, lizards and centipedes have been associated with causing rat lungworm disease in humans, according to a news release from UH on Monday.

Robert Cowie, senior author on the study and faculty member in UH Manoa’s School of Ocean and Earth Science and Technology, explained that the rat lungworm has a complex life cycle that involves slugs and snails as so-called “intermediate” hosts and rats as “definitive” hosts in which the worms reach maturity and reproduce. Both rats as well as people become infected when they eat an infected snail or slug, and this can lead to serious illness and occasionally death.

“But people can also get affected if they eat so-called paratenic hosts, which are also known as carrier hosts,” said Cowie, who is a research professor in SOEST’s Pacific Biosciences Research Center. “These are animals that become infected by eating infected snails or slugs, but in which the worms cannot develop to maturity as they do in a rat. However, in such hosts the worms become dormant, but still infective. And if one of these hosts, or part of one, is then eaten raw by a person — an accidental host — development can continue, but only up to a point.”

Rat lungworm development happens when they are in the person’s brain, where they move around, feed and grow, but then the worms die without completing their life cycle, according to the news release. The damage to the brain and the massive inflammation that results when they die is primarily what causes the symptoms of rat lungworm disease.

“It is important to know not only that snails and slugs can transmit rat lungworm parasites to humans but also which other animals — which paratenic hosts — can also do so,” Cowie said.

Prevention measures include avoiding eating species that may harbor the parasite, as well as washing all fruits and vegetables under running water and inspecting them for possible rat lungworm hosts, Cowie said.

Cowie supervised Helena Turck, first author and graduate student at the University of London. Professor Mark Fox of the Royal Veterinary College also collaborated on the study.

Today's breaking news and more in your inbox

ncG1vNJzZmivp6x7rq3UoqWer6NjsLC5jqecsKtfobykrctmpZ6vo2R%2FcX6RaGdxZ6OlsqS1xKxkqKyYmr9uwMeapWarnKq0tHnAp5tmq56Wtq2%2FjJyYp2Wkp66vv8yiq2aqkal6rcHNoK6oqp1iv6a%2FxJqpnKCVp8Bussinm2g%3D