Secernenteans: Secernentea

Physical characteristics: Adult rat lungworms are 0.8 to 1.3 inches (20 to 34 millimeters) long and 0.01 to 0.02 inch (320 to 560 micrometers) wide. The females are larger than the males.

Geographic range: Rat lungworms live all over the world in warm areas. Because they are found throughout the world, no distribution map is provided.

Habitat: The primary hosts of rat lungworms are rats. The intermediate hosts are animals such as snails, oysters, slugs, and crabs.

Diet: Rat lungworms feed on nutrients in the blood of their hosts, specifically around the lungs and brains of rodents and the lungs of humans.

Behavior and reproduction: Adult rat lungworms live in the blood vessels of the lungs of their hosts. Young worms in their first developmental stage enter the respiratory tract, move up the breathing tubes to the mouth, and then are swallowed. The worms move through the digestive tract and are passed in the host's feces (FEE-seez). They The primary hosts of rat lungworms are rats. The intermediate hosts are animals such as snails, oysters, slugs, and crabs. (Illustration by John Megahan. Reproduced by permission.) enter intermediate hosts, such as snails, which are eaten by rodents and humans. In rodents the worms travel to the pulmonary arteries and the lungs, where they mature. The adults eventually travel to the brain and travel back to the lungs through veins. In humans, the parasites enter the brain but do not develop further and die.

Rat lungworms and people: Rat lungworms are dangerous to humans because they rupture blood vessels in the brain, causing headache, fever, nerve damage, coma, and death.

Conservation status: Rat lungworms are not considered threatened or endangered. ∎