[Distribution of Paragonimus (Digenea: Troglotrematidae) in Antioquia Province, Colombia, based on metacercariae counts in freshwater crabs].

INTRODUCTION: Paragonimosis or lung fluke disease courses with signs similar to those seen in tuberculosis. The causative agent is a parasite of the genus Paragonimus (Digenea: Troglotrematidae). People become infected by ingesting raw or partially cooked crabs containing metacercariae. The first focus of human paragonimosis in Colombia was recorded in the county of Urrao, where two species of crabs infected with Paragonimus were found. In 2005, crabs with Paragonimus' metacercariae were captured near Medellín, western Colombia. This prompted a search for the parasite in other locations through its presence in the crabs.

OBJECTIVE: To establish the distribution of Paragonimus in Antioquia, we evaluated the presence of metacercaria in freshwater brachyuran crabs.

MATERIALS AND METHODS: From 2005 to 2007, crabs were captured in 13 counties of Antioquia. The crabs were relaxed and dissected to determine presence of trematodes and then to make the taxonomic identifications.

RESULTS: From 52 crabs captured in 9 counties, 42 (80.8%) were found with Paragonimus metacercariae. The crabs were identified as Pseudothelphusidae in 2 genera--Hypolobocera and Strengeriana--and were assigned to four species. Three of the species were recorded for the first time as hosts of Paragonimus.

CONCLUSIONS: A Paragonimus' distribution map was constructed for Antioquia; for the first time urban zones were included. Because of the high rate of infection, the handling and consumption of raw and poorly cooked crabs pose risk factors for human infection. Because crabs are affordable and provide means of easy diagnosis, crabs are targeted as primary agents of and diagnostic tools for paragonmosis.