THE ROLE OF TADPOLES AND FROGS AS PARATENIC HOSTS IN THE LIFE-CYCLE OF DRACUNCULUS-INSIGNIS (NEMATODA, DRACUNCULOIDEA)

The possibility exists that paratenic hosts play a role in the life cy cle of various Dracunculus species. In the present study, we establish ed that tadpoles of 2 genera of frogs (Xenopus and Rana) were capable of ingesting copepods infected with third-stage larvae (L3) of Dracunc ulus insignis. Once ingested, the L3s migrated from the gut to the som atic tissues of the tadpoles. In Xenopus, the dracunculid larvae persi sted through the metamorphosis of the tadpoles into adult frogs. These observations confirm the concept that paratenic hosts, such as tadpol es or frogs, may be important means of transporting infective larvae o f Dracunculus species up the food chain and facilitate transmission to the definitive hosts.