Horntail Snail Invades Florida, Can Spread Deadly Rat Lungworm Disease

Horntail snail and a rat. Credits: FDACS / yves Tennevin / Flickr cropped.

MIAMI, Florida – The horntail snail, an invasive species that can spread rat lungworm disease which can cause death, coma, or paralysis in humans and animals, has been positively identified by the Florida Department of Agriculture and Consumer Services in Miami-Dade County.

The horntail snail (Macrochlamys indica) was first discovered by a gastropod enthusiast in Coconut Grove who sent the unusual snail to the University of Florida for identification. This is the first time this snail has been found in the United States.

After investigative inspections, the snail was found at more sites in Miami-Dade County.

“The horntail snail is an invasive pest with the potential to cause serious health implications for Floridians,” stated Agriculture Commissioner Nikki Fried.

“Our Division of Plant Industry and essential industry partners are continuing to monitor this threat and working towards a plan to stop the horntail snail’s spread into other areas of Florida.”

The horntail snail is a well-known pest in India and feeds on a wide variety of commercial crops, including lettuce, beans, yams, chrysanthemums, etc.

They are voracious feeders that are most active at night and after rainfall.

The snail has a delicate amber-colored shell which measures about the size of a dime.

The horntail snail is named for the pointed fleshy protrusion (caudal horn) at the tip of its tail. When relaxed, the horntail snail has a flap of flesh that extends backward onto or around the shell, which differentiates it from other terrestrial snails in the state.

The snail prefers cool damp locations, so they may be found under pots or in moist soil. During dry, hot weather, they may burrow in the ground.

Deadly Rat Lungworm Host

As with other terrestrial snails in Florida, the horntail snail has the potential to be an intermediate host of rat lungworm, a parasitic nematode that can cause meningitis in humans.

Snails ingest rat lungworm larvae by eating infected rat feces. When a rat eats an infected snail, the larvae penetrate the rat’s intestine and enter its circulatory system, which transports them to the brain.

There, they develop into immature worms, re-enter the circulatory system, and travel to the rat’s pulmonary artery where they mature and reproduce.

When the new larvae hatch, they are coughed up and swallowed by the rat and pass through its feces, completing the life cycle.

In a survey of 18 counties, nearly 23 percent of rats, about 16 percent of rat fecal samples, and nearly 2 percent of land snails tested positive for the nematode, according to UF researchers.

Keep Children And Pets Away From Snails

Humans can ingest the parasite by consuming infected snails or infected frogs and crustaceans, which can also pick up the nematode.

Infection with rat lungworm can also cause meningitis in animals, as well as limb weakness or paralysis, neck pain, and central nervous system problems.

Rat Lungworm Symptoms

Clinical signs of infection in adults include headache, stiff neck, fever, vomiting, nausea, and paralysis of the face and limbs. The most common symptoms of infection in children are nausea, vomiting, and fever.

While the fatality rate of infection in humans is low, the parasite can cause eosinophilic meningitis if it becomes trapped and dies in the brain, and severe infections can cause coma or death.