A recent (2018) study using genetical analysis and experimental infections and life-cycles showed that two different distinct genotypes of D. caninum occur respectively in dogs and in cats, and suggested that two different species might be involved. Human infections
A human infection with D. caninum is rare, but if an infection does occur, it is more likely to occur in young children. As of the early 1960s, the number of cases of D. caninum in the U.S. was a mere 21. Therefore, human infection of Dipylidium caninum, or diplydiasis, is a rare occasion. It is largely agreed across the parasitology community that despite the reports of this disease occurring, there are very likely numerous cases that have gone unnoticed and unreported because of its subtle and minor pathology in humans, in addition to its scarceness in clinical records. The adult tapeworm grows within the host for 3–4 weeks after initial infection. The number of parasites the host is initially infected with is directly related to the number of cysticercoid juveniles present in the fleas coelom. The load of parasites present in the humans is lower, luckily, as the life cycle is not occurring in the ideal conditions or species as humans are not the definitive host.Many cases have an unexciting course of infection, as can be depicted in two cases occurring in the 1960s. The first case occurred in a 9-month-old female. Mother found motile proglottids the child’s diaper, later identified as D. caninum. The child had no apparent signs or symptoms.
The presumed source of infections was one of the family’s  four Labrador retrievers, two of which were found to already have been infected with D. caninum. The second additional case occurred in an 18-month-old male. Mother found motile proglottids in the child’s diaper and again, the child was symptom-free. A puppy in the household was found to be infected and thus was the source of the child infection. Young children and toddlers are at a greater risk of infection because of how they interact with their pets. A human may attain an infection by accidentally ingesting an infected flea through food contamination or through the saliva of pets. Most infections are asymptomatic, but sometimes these symptoms may be identified in an infected individual: mild diarrhea, abdominal colic, anorexia, restlessness, constipation, rectal itching, and pain due to emerging proglottids through the anal cavity. Treatment and prevention
As with most tapeworm infections, the drugs of choice to kill adult tapeworms are praziquantel or niclosamide. Pets can be prevented from becoming infested with tapeworm if they are treated prophylactically with a product which kills the intermediate host (the flea) before the infective metacestode can develop. Some isoxazoline products are registered to prevent flea tapeworm infestations using this method. Gallery
References
External links
tapeworms from The Pet Health Library