Morphological, Behavioral, and Molecular Characterization of Avian Schistosomes (Digenea: Schistosomatidae) in the Native Snail Chilina dombeyana (Chilinidae) from Southern Chile.

Pablo Oyarzún-Ruiz,Gonzalo Collado,Adriana Santodomingo,Richard Thomas,Lucila Moreno,Pamela Muñoz

doi:10.3390/pathogens11030332

Abstract

Avian schistosomes are blood flukes parasitizing aquatic birds and snails, which are responsible for a zoonotic disease known as cercarial dermatitis, a hypersensitive reaction associated to the cutaneous penetration of furcocercariae. Despite its worldwide distribution, its knowledge is fragmentary in the Neotropics, with most of data coming from Argentina and Brazil. In Chile, there are only two mentions of these parasites from birds, and one human outbreak was associated to the genus “Trichobilharzia”. However, the identity of such parasites is pending. The aim of this study was to identify the furcocercariae of avian schistosomes from Southern Chile using an integrative approach. Thus, a total of 2283 freshwater snails from different families were collected from three different regions. All snails were stimulated for the shedding of furcocercariae, but only Chilina dombeyana (Chilinidae) from the Biobío region was found to be parasitized. The morphology and phylogenetic analyses of 28S and COI genes stated two lineages, different from Trichobilharzia, shared with Argentina. This study provides new information on Neotropical schistosomes, highlighting the need for major research on these neglected trematodes, which are considered to be emerging/re-emerging parasites in other parts of the globe as consequence of anthropogenic disturbances and climatic change. Highlights: 1. Two different lineages (Lineage I and II) were described and molecularly characterized (28S and COI genes); 2. Cercaria chilinae I y II are proposed as a synonymous of Lineage II. Thus, a total of four different lineages of avian schistosomes are related to Chilina spp.; 3. Chilina spp. represents an important intermediate host for avian schistosomes in South America, constituting a reservoir de schistosomes with zoonotic potential; 4. Coinfection between the two different lineages was found, a finding previously not reported for avian schistosomes; 5. Expansion in the geographic distribution of Nasusbilharzia melancorhypha from its original record in Argentina, with Chilina dombeyana as an additional intermediate host.

Highlights

Avian schistosomes are parasitic flukes inhabiting the blood stream of aquatic birds of different orders
Two lineages of furcocercariae were recognized from C. dombeyana, with Lineage I isolated from 5 snails and Lineage II from 22 snails
Two different lineages of avian schistosomes from C. dombeyana were recorded, each one distinctive from the other in terms of their morphology and morphometry, and they were further supported by molecular data

Summary

Introduction

Avian schistosomes are parasitic flukes inhabiting the blood stream of aquatic birds of different orders This group of flukes is composed of 11 described genera, the genus Trichobilharzia is considered to be the most specious taxon with about 40 species [1–4]. The lifecycle of this group of flukes involves aquatic birds as the definitive hosts, where adult worms will copulate and release their eggs through feces, for visceral schistosomes, or through nasal secretions, in the case of nasal schistosomes [3,5]. The miracidium hatches and looks for its specific intermediate host, an aquatic snail Inside the gastropod, it transforms to sporocysts, which are intimately associated with the hepatopancreas. After about 3–10 weeks, these sporocysts start to produce furcocercariae, which are released into the water column, where they begin their search for a definitive host and restart the lifecycle [3,5,6]

Objectives

Methods

Results

Conclusion