Dipylidium

Dipylidium is a genus of tapeworms (class Cestoda) in the family Dipylidiidae. The most clinically important member is Dipylidium caninum, a tapeworm of dogs and cats, though several Dipylidium species can parasitize carnivores. Humans can become accidental hosts, typically children, after ingesting an infected flea or chewing lice.

Life cycle and transmission: Adult Dipylidium reside in the small intestine of the definitive host. Gravid proglottids detach and pass in the feces; each proglottid contains egg packets. The eggs are released when the packets rupture. An intermediate host, usually a flea (commonly Ctenocephalides felis) or sometimes a chewing louse, ingests the eggs and develops a cysticercoid within the insect. The definitive host becomes infected by ingesting an infected flea during grooming or other activities. The parasite then develops into an adult tapeworm in the small intestine.

Clinical features and diagnosis: In pets, Dipylidium infections are often asymptomatic but can cause mild digestive upset or anal irritation due to the presence of gravid proglottids. Proglottids may be seen around the anus or in the feces, and pets may shed rice-grain–like segments. Diagnosis is typically by fecal flotation detecting egg packets or by identifying the characteristic segments in the stool or around the perianal area. Human infection is rare but possible, often identified by the same proglottid or egg packet signs.

Treatment and prevention: Effective treatments include praziquantel or epsiprantel, usually with a dose or short course as recommended by a veterinarian. Preventing reinfection focuses on comprehensive flea control for pets and the environment, along with regular deworming as advised. Reducing flea populations lowers the risk of transmission to pets and accidental hosts.