metacercarie

A metacercaria is a larval stage in the life cycle of certain trematode (flukes) and cestode (tapeworms) parasites. These parasites typically undergo a complex life cycle involving multiple hosts, including humans. The term "metacercaria" is derived from the Greek words "meta" meaning "after" and "kercaria" referring to the cercaria stage, which is the immediate precursor to the metacercaria stage.

Metacercariae are often found in intermediate hosts, such as fish, crustaceans, or mollusks, where they develop further before being ingested by the definitive host, which is usually a mammal, including humans. In the definitive host, the metacercariae mature into adult worms, completing the life cycle.

The metacercaria stage is characterized by its ability to survive and develop in the intermediate host's environment. This stage is crucial for the parasite's survival and transmission, as it allows the parasite to evade the host's immune system and continue its life cycle.

Metacercariae can be identified by their morphological features, such as their size, shape, and the presence of specific structures like hooks or suckers. They can also be detected using molecular techniques, such as polymerase chain reaction (PCR), which target specific genes or sequences unique to the parasite species.

The study of metacercariae is important for understanding the ecology and epidemiology of trematode and cestode parasites, as well as for developing control measures to prevent human infections.