Tongue Worms: Pentastomida

Physical characteristics: Tongue worms are long, tongue-shaped worms. The males are 0.71 to 0.79 inches (18 to 20 millimeters) in length, while the females are 3.15 to 4.72 inches (80 to 120 millimeters).

Geographic range: They are found worldwide, especially in warm tropical regions. Because they are found throughout the world, no distribution map is provided.

Habitat: Adult tongue worms live in the noses of dogs, foxes, coyotes, wolves, and cats (definitive hosts). They rarely infect people. The larvae infest the tissues and organs of rabbits, horses, goats, and sheep (intermediate hosts).

Diet: Adults eat the tissues and secretions lining the nasal passages and sinuses. The larvae feed on blood and lymph (limf) of the hosts. Lymph is a yellowish body fluid filled with white blood cells.

Behavior and reproduction: Both males and females are required for mating. Males only mate with females that are close to their own size. The bodies of females may contain up to five hundred thousand eggs at a time and can produce several million eggs in their lifetime. Fertilized eggs are sneezed out or swallowed and passed from the body with solid waste. Intermediate hosts, such as rodents, cattle, sheep, and goats, accidentally swallow the eggs with their food. The eggs hatch into four-legged larvae that travel through blood vessels into the lungs and the digestive organs. The larvae must molt six to eight times before they become infective cysts. Definitive hosts, dogs and their relatives, eat the infested flesh. When swallowed, the larvae go directly into the air passages and sinuses associated with the nose inside the head. There they develop into adults.

Tongue worms live in the noses of dogs, foxes, coyotes, wolves, and cats. (Illustration by The Gale Group.)

Tongue worms and people: People living in the Middle East, India, Africa, southeast Asia, and the East Indies are sometimes infected with the larvae. Infections are usually the result of eating raw glands of cattle, sheep, and goats that have the larvae. These glands are considered a special treat in these parts of the world. People may not be aware that they have an infestation or suffer from irritation in their nose and throat. Deaths have been reported due to blocked air passages. Larval infestations also occur when the eggs are accidentally swallowed. There is no cure for infestations in dogs or humans, but most single infestations disappear after a year.

Conservation status: Tongue worms are not considered threatened or endangered by the World Conservation Union (IUCN). ∎