High prevalence of Trichomonas gallinae in wild columbids across western and southern Europe

Melanie Marx,Benjamin Metzger,Gregorio Rocha,Petra Quillfeldt,Simon J Goodman,Sylvia L Mayr,Juan F Masello,Klaus Hillerich,Tanja Romeike,Hermann Willems,Fernando Spina,Rebecca C Thomas,Keith C Hamer,Luciano Calderón,Jacopo G Cecere,Jenny C Dunn,Gerald Reiner,Steffen Koschkar,Sarah Moussa

doi:10.1186/s13071-017-2170-0

Abstract

BackgroundAvian trichomonosis is known as a widespread disease in columbids and passerines, and recent findings have highlighted the pathogenic character of some lineages found in wild birds. Trichomonosis can affect wild bird populations including endangered species, as has been shown for Mauritian pink pigeons Nesoenas mayeri in Mauritius and suggested for European turtle doves Streptopelia turtur in the UK. However, the disease trichomonosis is caused only by pathogenic lineages of the parasite Trichomonas gallinae. Therefore, understanding the prevalence and distribution of both potentially pathogenic and non-pathogenic T. gallinae lineages in turtle doves and other columbids across Europe is relevant to estimate the potential impact of the disease on a continental scale.ResultsWe examined 281 samples from four wild columbid species for Trichomonas infection and determined the genetic lineages. The overall prevalence was 74%. There were significant differences between the species (P = 0.007). The highest prevalence was found in stock doves Columba oenas (86%, n = 79) followed by wood pigeons Columba palumbus (70%, n = 61) and turtle doves (67%, n = 65), while three of five collared doves Streptopelia decaocto (60%) were infected. We found seven different lineages, including four lineages present in columbids in the UK, one lineage already described from Spain and three new lineages, one of those found in a single turtle dove migrating through Italy and another one found in a breeding stock dove. Stock doves from Germany and collared doves from Malta were infected with a potentially pathogenic lineage (lineage A/B), which is known to cause lesions and mortality in columbids, raptors and finches.ConclusionsGenerally, turtle doves showed high prevalence of Trichomonas infection. Furthermore, the potentially pathogenic lineage A/B (or genotype B according to previous literature) was found in a recovering stock dove population. Both findings are worrying for these columbid species due to the occasional epidemic character of trichomonosis, which can have severe negative effects on populations.

Highlights

Avian trichomonosis is known as a widespread disease in columbids and passerines, and recent findings have highlighted the pathogenic character of some lineages found in wild birds
Trichomonosis has been detected in wild European columbid species including collared doves Streptopelia decaocto, stock doves Columba oenas, wood pigeons Columba palumbus and European turtle doves Streptopelia turtur [3, 12, 15,16,17]
The aims of the present study were to (i) test whether turtle doves migrating through Italy and Malta, along the central/eastern flyway [18], have similar prevalence and genetic lineages of Trichomonas as birds along the western flyway; (ii) obtain baseline data on prevalence and genetic lineages of Trichomonas in a recovering population of stock doves in Germany; and (iii) provide information from a larger sample of turtle doves, collared doves, stock doves and wood pigeons migrating along the western flyway, with a focus on the potentially pathogenic lineages, which are known to cause gross lesions and mortality in columbids, raptors and finches [12, 14]

Summary

Introduction

Avian trichomonosis is known as a widespread disease in columbids and passerines, and recent findings have highlighted the pathogenic character of some lineages found in wild birds. Trichomonosis can affect wild bird populations including endangered species, as has been shown for Mauritian pink pigeons Nesoenas mayeri in Mauritius and suggested for European turtle doves Streptopelia turtur in the UK. The disease trichomonosis is caused only by pathogenic lineages of the parasite Trichomonas gallinae. The protozoan parasite Trichomonas gallinae infects captive and wild bird species across the world and can lead to the avian disease called trichomonosis. Due to its widespread occurrence and sometimes pathogenic character, it is thought to play a role in the regulation of wild bird populations [1,2,3,4,5]. Trichomonosis has been detected in wild European columbid species including collared doves Streptopelia decaocto, stock doves Columba oenas, wood pigeons Columba palumbus and European turtle doves Streptopelia turtur (hereafter turtle doves) [3, 12, 15,16,17]

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