Copepod consumption by amphibians and fish with implications for transmission of Dracunculus species

• Published in: International journal for parasitology. Parasites and wildlife Vol. 15; pp. 231 - 237
• Main Authors: Box, Erin K., Cleveland, Christopher A., Garrett, Kayla B., Grunert, Ryan K., Hutchins, Katherine, Majewska, Ania A., Thompson, Alec T., Wyckoff, Seth T., Ehlers, Coles, Yabsley, Michael J.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2021; Elsevier
• Subjects: Amphibian; Copepod; Dracunculus; Fish; Paratenic host; Regular; Transport host; Dracunculus; Copepod; Fish; Paratenic host; Amphibian; Transport host
• ISSN: 2213-2244; 2213-2244
• DOI: 10.1016/j.ijppaw.2021.06.001

Parasitic nematodes in the genus Dracunculus have a complex life cycle that requires more than one host species in both aquatic and terrestrial habitats. The most well-studied species, Dracunculus medinensis, is the causative agent of human Guinea worm disease (dracunculiasis). There are several other Dracunculus species that infect non-human animals, primarily wildlife (reptiles and mammals). The classic route of D. medinensis transmission to humans is through the ingestion of water containing the intermediate host, a cyclopoid copepod, infected with third-stage larvae (L3s). However, many animal hosts (e.g., terrestrial snakes, dogs) of other Dracunculus sp. appear unlikely to ingest a large number of copepods while drinking. Therefore, alternative routes of infection (e.g., paratenic or transport hosts) may facilitate Dracunculus transmission to these species. To better understand the role of paratenic and transport hosts in Dracunculus transmission to animal definitive hosts, we compared copepod ingestion rates for aquatic species (fish, frogs [tadpoles and adults], and newts) which may serve as paratenic or transport hosts. We hypothesized that fish would consume more copepods than amphibians. Our findings confirm that African clawed frogs (Xenopus laevis) and fish consume copepods, but that fish ingest, on average, significantly higher numbers (68% [34/50]) than adult African clawed frogs (36% [18/50]) during a 24-h time period. Our results suggest that amphibians and fish may play a role in the transmission of Dracunculus to definitive hosts. Still, additional research is required to determine whether, in the wild, fish or frogs are serving as paratenic or transport hosts. If so, they may facilitate Dracunculus transmission. However, if these animals simply act as dead-end hosts or as means of copepod population control, they may decrease Dracunculus transmission. [Display omitted] •Copepod ingestion during 24 h was assessed for fish and amphibians.•Significant numbers of copepods were consumed by fish and adult Xenopus.•Tadpoles and newts did not consume large numbers of copepods during this time.•Fish and amphibians may facilitate Dracunculus transmission.•Further studies may elucidate how copepod ingestion impact parasite transmission.