May 25 - Taenia taniaeformis

This photo may exceed the “yuck factor” for some. Taenia taniaeformis is the common tapeworm of house cats and is also found in other species of felids. The eggs pass out in the feces and are ingested by various species of rodents, where they develop into cysts, usually in the liver. Pictured is a cotton rat, a very common rodent in the southeastern United States. The dissected liver has some large white cysts. If a cyst is opened, it contains what looks like an adult tapeworm with a fluid-filled bladder at the end. This stage is called a strobilocercus. When the rodent is ingested by a cat, only the head of the tapeworm survives, which then develops into an adult. Because of this type of life cycle, a house cat with tapeworms poses little danger to its owners. Thanks to Dr. Christine Miller of the Miami Metrozoo for providing this (yucky) photo.

Contributed by Mike Kinsella.