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

• Type of Material: Article
• Authors: Erin K Box, University of Georgia, Athens; Christopher A Cleveland, University of Georgia, Athens; Kayla B Garrett, University of Georgia, Athens; Ryan K Grunert, University of Georgia, Athens; Katherine Hutchins, University of Georgia, Athens; Ania A Majewska, Emory University; Alec T Thompson, University of Georgia, Athens; Seth T Wyckoff, University of Georgia, Athens; Coles Ehlers, University of Georgia, Athens; Michael J Yabsley, University of Georgia, Athens
• Language: English
• Date: 2021-08-01
• Publisher: Elsevier
• Publication Version: Final Published Version
• Copyright Statement: © 2021 The Authors
• License: Creative Commons Attribution-NonCommercial 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.ijppaw.2021.06.001
• Title of Journal or Parent Work: International Journal for Parasitology-Parasites and Wildlife
• Volume: 15
• Start Page: 231
• End Page: 237
• Grant/Funding Information: Additional support was provided by the wildlife management agencies of the Southeastern Cooperative Wildlife Disease Study member states through the Federal Aid to Wildlife Restoration Act (50 Stat. 917) and by a U.S. Department of the Interior Cooperative Agreement.; This work was supported by The Carter Center; a full listing of Carter Center supporters is available at http://www.cartercenter.org/donate/corporate-government-foundation-partners/index.html.
• Keywords: Fish; Paratenic host; Transport host; Copepod; Dracunculus; Amphibian
• Research Categories: Agriculture, Forestry and Wildlife; Biology, Veterinary Science

Abstract

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.