Persistence of Trichomonas gallinae in Birdseed.

Trichomonas gallinae has emerged worldwide as a cause of mortality in songbirds (passerines). The congregation of numerous birds, including the reservoir hosts, pigeons and doves (columbids), at backyard feeding and watering sources has been suggested as a potential driver for the outbreaks. Evidence supporting a role for water in transmission has been established, but the role of birdseed in the transmission of trichomoniasis remained to be investigated. We assessed the survival of T. gallinae in three commercial birdseeds (mixed seed, black-oil sunflower seed, and niger seed) routinely used to attract passerine birds to local properties. Trichomonad suspensions were inoculated (low dose: 1 × 103; high dose: 1 × 105) into each of the three seed types in petri dishes, using both dry and moist (water-soaked) conditions, in triplicate. Petri dishes were incubated at 37 C and monitored for T. gallinae survival for 48 hr by wet-mount microscopy and by InPouch™ TF medium culture for 10 days. Surviving trichomonads were not detected in any of the dry birdseed treatments. In moist conditions, however, trichomonads were found to survive ≤24 hr in all three seed types and ≤48 hr in the mixed seed that contained organic debris. We demonstrate that T. gallinae has the ability to survive in moist birdseed, which suggests that public bird-feeding sites may play a significant role in the transmission of trichomoniasis.

Molecular characterization of Trichomonas gallinae isolates recovered from the Canadian Maritime provinces' wild avifauna reveals the presence of the genotype responsible for the European finch trichomonosis epidemic and additional strains.

Finch trichomonosis, caused by Trichomonas gallinae, emerged in the Canadian Maritime provinces in 2007 and has since caused ongoing mortality in regional purple finch (Carpodacus purpureus) and American goldfinch (Carduelis tristis) populations. Trichomonas gallinae was isolated from (1) finches and rock pigeons (Columbia livia) submitted for post-mortem or live-captured at bird feeding sites experiencing trichomonosis mortality; (2) bird seed at these same sites; and (3) rock pigeons live-captured at known roosts or humanely killed. Isolates were characterized using internal transcribed spacer (ITS) region and iron hydrogenase (Fe-hyd) gene sequences. Two distinct ITS types were found. Type A was identical to the UK finch epidemic strain and was isolated from finches and a rock pigeon with trichomonosis; apparently healthy rock pigeons and finches; and bird seed at an outbreak site. Type B was obtained from apparently healthy rock pigeons. Fe-hyd sequencing revealed six distinct subtypes. The predominant subtype in both finches and the rock pigeon with trichomonosis was identical to the UK finch epidemic strain A1. Single nucleotide polymorphisms in Fe-hyd sequences suggest there is fine-scale variation amongst isolates and that finch trichomonosis emergence in this region may not have been caused by a single spill-over event.

Detection and characterization of a Trichomonas isolate from a rehabilitated bald eagle (Haliaeetus leucocephalus).

A hatching-year bald eagle (Haliaeetus leucocephalus) was presented for clinical examination after being found unable to fly. Upon admission, routine wet-mount microscopy detected no trichomonads. Five months later, oral cavity inspection found no abnormalities, but the eagle was swabbed for research on trichomonosis in maritime birds. The swab was used to inoculate an InPouch TF culture and trichomonads were visible within 24 hr. Genotyping (ITS) revealed a Trichomonas isolate that was 100% identical to an isolate from a bearded vulture (Gypaetus barbatus) from the Czech Republic. The eagle was treated with metronidazole (50 mg/kg q 12h PO for 5 consecutive days). Following treatment, the eagle was swabbed and the inoculated InPouch TF culture was monitored daily for 1 wk. No trichomonads were observed. Rehabilitation centers interested in surveillance should consider combining the InPouch TF technique with clinical inspection of live birds to confirm trichomonosis and for future research.