Trichomonads in birds – a review

Abstract

Members of the family Trichomonadidae, mainly Trichomonas gallinae and Tetratrichomonas gallinarum, represent important parasites in birds with worldwide presence, since being reported in the 19th century. Especially Columbiformes, Falconiformes and Strigiformes can be severely affected by trichomonads, whereas the majority of infections in Galliformes and Anatiformes are subclinical although severe infections are occasionally reported. With the recent appearance of deadly infections in wild Passeriformes the protozoan parasite T. gallinae obtained greater attention which will be addressed in this review. Although light microscopy remains the method of choice to confirm the presence of trichomonads molecular studies were introduced in recent years, in order to characterize the parasites and to establish relationships between isolates. Isolation of trichomonads is a prerequisite for detailed in vitro and in vivo studies and different media are reported to obtain suitable material. The limited information about virulence factors will be reviewed in context with the pathogenicity of trichomonads which varies greatly, indicating certain strain heterogeneity of the parasites. Options for treatment characterized by the leading role of imidazoles whose activity is sometimes hampered by resistant parasites remains a challenge for the future. Introducing more standardized genetic studies and investigations concentrating on the host-pathogen interaction should be helpful to elucidate virulence factors which might lead to new concepts of treatment.

Genetic characterization of oropharyngeal trichomonad isolates from wild birds indicates that genotype is associated with host species, diet and presence of pathognomonic lesions

“…Clinical signs of infection can vary from asymptomatic to dysphagia, regurgitation, sialorrhea/ptyalism and even death by starvation, because birds become unable to feed. Some isolates/species are able to induce necrotic foci on internal organs, such as the liver, and severe cases can be lethal as early as 4 days after infection (revised in Amin et al, 2014). The reservoir hosts for T. gallinae are columbid species.…”

“…The transmission is maintained in the wild by predation and necrophagy from raptors or by sharing contaminated food or water sources between columbids and other birds (finches; Lawson et al, 2011a, b). The most frequent presentation is an endemic process with high morbidity but low mortality rates on adult columbids, although occasional outbreaks of the disease causing high mortality have been reported (revised in Amin et al, 2014). In fact, trichomonosis has been detected as one of the concerns for the endangered pink pigeon (Columba mayeri) in Mauritius and for Bonelli's eagle (Aquila fasciata) in Spain and Portugal (Höfle et al, 2000;Real et al, 2000;Bunbury et al, 2007).…”

“…In fact, trichomonosis has been detected as one of the concerns for the endangered pink pigeon (Columba mayeri) in Mauritius and for Bonelli's eagle (Aquila fasciata) in Spain and Portugal (Höfle et al, 2000;Real et al, 2000;Bunbury et al, 2007). Recently, it has been described as an emerging disease for passerines, as trichomonosis has been reported in epidemic focuses involving finch species in the UK, Canada, Slovenia and Austria as well as other European countries (reviewed in Amin et al, 2014).…”

“…This region is widely used for phylogenetic purposes and is recognized as a strong molecular tool to determine inter-specific and intra-specific diversity (revised in Amin et al, 2014).…”

Systematics, biology and invasiology of trichomonads (Trichomonadida) - the current state of knowledge

“…Formy inwazyjne mimo swej wrażliwości utrzymują stan inwazyjności do kilku dni w wilgotnym środo-wisku, stwarzając zagrożenie przeniesienia inwazji. U zwierząt istotna jest także szeroko rozumiana higiena żywienia oraz izolacja poideł i karmników od zwierząt wolno żyjących, będących często rezerwuarem inwazji (3,101).…”