Dipylidium is tapeworm of cats and dogs. People become infected when they accidentally swallow a flea infected with tapeworm larvae; most reported cases involve children. Dipylidium infection is easily treated in humans and animals.

The most common tapeworm of dogs and cats in the United States is called Dipylidium caninum. Infection is common and found throughout the world.

By swallowing a flea infected with a tapeworm larvae. A dog or cat may swallow a flea while self-grooming. Once the flea is digested by the dog or cat, the larval tapeworm is able to develop into an adult tapeworm.

The adult tapeworm is made up of many small segments, called proglottids, each about the size of a grain of rice. Adult tapeworms may measure 4-28 inches in length. As the tapeworm matures inside the intestine, these segments (proglottids) break off and pass into the stool.

Although cats and dogs are rarely ill as a result of a Dipylidium tapeworm infection, the proglottids can sometimes be seen crawling near the anus or on the surface of a fresh bowel movement. Proglottids contain tapeworm eggs; these eggs are released into the environment when the proglottid dries out. The dried proglottids are small (about 2 mm), hard and yellowish in color and can sometimes be seen stuck to the fur around the pet’s anus.

Tapeworms are not usually harmful to your pet. Weight loss may occur if your pet is heavily infected. Sometimes, an infected dog will “scoot” or drag its anus across the ground or carpet because the segments are irritating to the skin in this area.

Occasionally, a portion of this tapeworm will be passed when the dog vomits. If this happens, a worm several inches long may be seen.

Tapeworm infection is usually diagnosed when the moving segments are seen crawling around the anus or in a bowel movement. Dipylidium tapeworm eggs are rarely released into the feces and are therefore not usually detected by routine fecal exams performed by your veterinarian. Because of this, veterinarians depend on you to notify them of possible tapeworm infection in your pet.

Yes; however, the risk of infection with this tapeworm in humans is very low. For a person to become infected with Dipylidium, he or she must accidentally swallow an infected flea. Most reported cases involve children. The most effective way to prevent infections in pets and humans is through flea control. A child who is infected will usually pass proglottids (or what appears as rice) in a bowel movement or find them stuck to the skin around the anal area.

Treatment for both animals and humans is simple and very effective. A prescription drug called praziquantel is given, either orally or by injection (pets only). The medication causes the tapeworm to dissolve within the intestine. Since the worm is usually digested before it passes, it may not be visible in your dog’s stool. The drugs are generally well-tolerated.

What should I do if I think my child is infected with tapeworms?

See your health care provider for diagnosis and treatment.

To reduce the likelihood of infection you should:

• Control fleas on your pet, and in their indoor and outdoor environments.
• Have your veterinarian treat your dogs and cats promptly if they have tapeworms.
• Clean up after your pet, especially in playgrounds and public parks. Bury the feces, or place it in a plastic bag and dispose of it in the trash.
• Do not allow children to play in areas that are soiled with pet or other animal feces.
• Teach children to always wash their hands after playing with dogs and cats, and after playing outdoors.

Causal Agent

Dipylidium caninum is a common tapeworm of dogs and cats, but is occasionally found in humans. It has many common names including the “flea tapeworm”, “cucumber tapeworm”, and “double-pored tapeworm”.

Life Cycle

Gravid proglottids are passed intact in the feces or emerge from the perianal region of the host (1). In the environment, the proglottids disintegrate and release egg packets, which are also occasionally found free in the feces (2). The intermediate host (most often larval stages of the dog or cat flea Ctenocephalides spp.) ingests egg packets, and the oncosphere within is released into the larval flea’s intestine. The oncosphere penetrates the intestinal wall, invades the insect’s hemocoel (body cavity), and develops into a cysticercoid (3). The cysticercoid remains in the flea as it matures from a larva into an adult (4). The vertebrate host becomes infected by ingesting the adult flea containing the cysticercoid (5). In the small intestine of the vertebrate host, the cysticercoid develops into the adult tapeworm after about one month. The adult tapeworms (measuring up to 60 cm in length and 3 mm in width) reside in the small intestine of the host, where they each attach by their scolex (6). Gravid, double-pored proglottids detach from the strobila (body) and are shed in the feces.

Humans also acquire infection by ingesting the cysticercoid contaminated flea. Children are most frequently infected, possibly due to close contact with flea-infested pets.

Hosts

Canids and felids are the normal hosts for Dipylidium caninum. The intermediate host is usually the larval stages of the dog or cat flea (Ctenocephalides spp.) and occasionally Trichodectes canis (the dog louse).

Geographic Distribution

Worldwide; this tapeworm is ubiquitous and common among pet dogs and cats. Human infection is rare, but has been reported from every inhabited continent.

Clinical Presentation

Most infections with Dipylidium caninum are asymptomatic. Pets may exhibit behavior to relieve anal pruritis (such as scraping anal region across grass or carpeting). Mild gastrointestinal disturbances may occur. The most striking feature in animals and children consists of the passage of proglottids. These can be found in the perianal region, in the feces, on diapers, and occasionally on floor covering and furniture. The proglottids are motile when freshly passed and may be mistaken for maggots or fly larvae.