![]() Eggs are produced within 2-3 weeks of infection of the dog or cat this short pre-patent period has implications for epidemiology and control.Tapeworms are an intestinal parasite. Here the infective stage is released from the intermediate host tissues, attaches to the mucosa of the small intestine using the scolex, produces segments and completes its development to an adult. The life cycle continues when the cysticercoid in the infected flea is eaten by a dog or a cat or other suitable definitive host. Each cysticercoid contains only a single protoscolex and each protoscolex has the potential to become the scolex of an adult tapeworm. The cysticercoid remains in the flea as it develops through its larval stages to the pupa and ultimately to an adult flea. ![]() The hexacanth larva released from each egg then penetrates the GI wall and migrates to the body cavity, where it develops into a cysticercoid, which is the metacestode stage for cyclophyllid tapeworms that utilize invertebrate intermediate hosts. In the arthropod intermediate host (required for completion of the life cycle), the eggs hatch in the GI system. Gravid segments, which are full of egg packets, drop off and pass intact in the feces or, rarely, disintegrate in the GI lumen, releasing the egg packets, which are also passed in the feces.Įgg packets, or eggs, are ingested by a suitable flea larva (or possibly a chewing louse) although the epidemiological significance of lice is not known. caninum live in the small intestine of the definitive hosts and, like all cestodes of veterinary importance, are hermaphrodites. Details of the egg packets are not always easily visible in the segments.Īdult D. Each egg has a fragile shell and contains a typical hexacanth larva with six hooks. In most specimens submitted to a diagnostic laboratory, the genital pores and the egg packets are the only structures visible, even in fixed, stained specimens. Each egg packet measures up to 200 µm in diameter and contains up to approximately 30 eggs, each of which is approximately 25 to 50 µm in diameter. caninum are grouped in very distinctive egg packets (egg capsules) throughout the central area of the segment. caninum contains two sets of reproductive organs, each with a lateral genital pore at about the mid-point of each lateral margin of the segment. Behind the rostellum are four circular, muscular suckers. At the anterior tip of the scolex is a rostellum, which is armed with several circles of hooks. Typically, anterior immature segments are smaller than mature and gravid segments towards the posterior. caninum are large (up to 50 cm in length, or more) and have an anterior scolex (attachment or holdfast organ), behind which is the ribbon-shaped, segmented body of the tapeworm. caninum on animal or human health.Īdult D. Treatment for this tapeworm should always be coupled with control of flea intermediate hosts but detection of fleas should not automatically result in prescription of a cestocide, especially as there is little perceptible impact of D. caninum following ingestion of an infected dog or cat flea. Rarely people, especially children, can become infected with D. ![]() The short pre-patent period of the parasite (2-3 weeks) means that when segments (resembling cucumber seeds) re-appear in feces shortly after treatment, this can be a result of rapid re-infection from poorly controlled flea infestations, or, as recently described, emerging resistance to cestocides. Diagnosis is challenging because segments are the most common fecal stage, and neither they nor the large egg packets are likely to be detected on routine fecal flotation. Dipylidium caninum is relatively non-pathogenic. Dogs and cats acquire the parasite by ingesting infected fleas or lice containing the cysticercoid infective stage. ![]() Like all tapeworms, the parasite has an indirect life cycle, with fleas (and possibly canine chewing lice) serving as intermediate hosts. Summary Dipylidium caninum is a tapeworm of the small intestines of domestic dogs and cats generally found in warmer and more humid regions of Canada, such as southern coastal BC. ![]()
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