Trichomoniasis in Finches – the American Goldfinch
In fall 2007, two incidents of purple finch, Carpodacus purpureus, mortality involving 4 -5 birds each, were reported from mainland Nova Scotia (NS). One finch was submitted for post mortem examination from one location, and two finches were submitted from the other. The submission included immature and adult and male and female birds. They were all emaciated, and one finch from each location had a severely ulcerated and necrotic lesion in the oral cavity and/or esophagus. The tissue damage was of sufficient severity to have substantially reduced ingestion of food and possibly precluded eating entirely. Therefore, this would have been the primary cause of their poor body condition. Microscopically, Trichomonas sp., a protozoan parasite, was identified as the cause of the lesion.
Trichomoniasis, the disease caused by this infectious organism, is a well documented illness affecting many bird species, but it is primarily diagnosed in pigeons and doves (also known as canker in these birds) and raptors (also know as frounce in these birds). Trichomoniasis has also been reported in various species of passerine birds, particularly sparrows and finches, and, since 2005, has emerged as a new cause of significant mortality in populations of greenfinch (Carduelis chloris) and chaffinch (Fringella coelebs) in the United Kingdom (UK), where it is known as trichomonosis (Duff et. al., 2007. The Veterinary Record. 161: 828). Similar to the pattern of disease occurrence associated with trichomoniasis in the UK, the seasonality of purple finch mortality in NS was late summer and early fall. This is unlike salmonellosis in songbirds which typically occurs in the winter. Although the history did not state it clearly, purple finch mortality in NS may have happened around bird feeders. If so, this would be another factor shared with the UK where mortality caused by trichomoniasis in finches is associated with the practice of bird feeding. Lastly, the incident locations in NS were separated by approximately 300 km (i.e., Bridgewater and River John), suggesting the possibility of a widespread problem in the purple finch population. (Scott McBurney and Maria Forzan, CCWHC, Atlantic Region)
Individuals who are interested in monitoring for the occurrence of trichomoniasis and/or preventing the disease from becoming a problem at their bird feeders can refer to the Garden Bird Health Initiative or the Royal Society for the Protection of Birds for further information. Information includes clinical signs and spread of the disease as well as recommendations regarding prevention. (modified from the CCWHC Spring 2008 Newsletter, 13-2).
Update for 2008 – the American goldfinch is also involved:
A purple finch from Cook Brook, NS, was diagnosed as having died of trichomoniasis on early July, 2008. Since then, 4 other finches from various locations in Nova Scotia, 1 finch from PEI and 2 finches from New Brunswick (see map) have been examined and diagnosed with trichomoniasis. The finches from New Brunswick were American goldfinches, Carduelis tristis, not purple finches. Purple finches dying of trichomoniasis were noted in NS last year, but, similar to the pattern reported in Great Britain, the mortalities occurred in late summer and early fall. The problem appears to be occurring earlier this year.
We would like to encourage investigation of finch mortalities and submission of suitable specimens for cause of death determination. Also, we would be interested to hear about purple finch mortalities that might be occurring in other provinces in Atlantic Canada. We are in communication with Veterinary Pathologists in Nova Scotia, New Brunswick and Newfoundland and Labrador, in an effort to monitor this problem more effectively.