Confirmed cases of trichomonosis in bird feeders – Quebec
Since mid-August, a few sick birds showing clinical signs suggestive of trichomonosis have been reported to the Quebec Regional Center. These cases have been observed in the regions of Montreal and Sherbrooke. Infection with Trichomonas gallinae has been confirmed following laboratory analysis of a house finch (Haemorhous mexicanus) that was submitted for analysis. This bird, which was found dead near a bird feeder after showing difficulty swallowing and weakness. The autopsy performed at the CWHC Quebec Regional Center revealed oral ulcerative and proliferative lesions highly suggestive of trichomonosis. The presence of the parasite was confirmed by molecular analysis using a PCR test.
Trichomonosis is a disease caused by a protozoan parasite, Trichomonas gallinae. This parasite was recognized as an emerging infectious disease of finches in Great Britain in 2005. In 2007, the first cases of trichomonosis in garden birds were documented in the Canadian Atlantic provinces. The exact cause of the emergence of this disease remains unclear. However, it is suspected that passerines using bird feeders become infected following contact with Columbiformes (pigeons and mourning doves) which are recognized as being the main carriers of this parasite. Transmission can occur either through direct contact with an infected bird or through the consumption of seeds contaminated with the parasite. Indeed, this protozoan can survive a certain period of time outside the bird in a humid and warm environment. Its spread is therefore facilitated during periods of heat by the presence of feeders and baths contaminated by infected birds. For this reason, this condition is mostly seen in late summer and early fall. The most common species affected by this condition are Fringillidae (finches, goldfinches), but birds of prey can also become infected by consuming infected birds. The protozoan colonizes the upper digestive tract, particularly the oral cavity and the esophagus, causing ulcerative lesions in the mucosa. These painful lesions cause difficulty when eating. Infected birds thus have difficulty swallowing and death from starvation may result. Note that this parasite does not affect humans nor other mammals.
The increase in feeding practices during the summer could explain the emergence of this condition in recent years. Indeed, this practice promotes the aggregation of birds during warm periods, those more favourable to transmission. Bird feeding is a very popular activity which is associated with benefits for both the birds and the people; this activity is often one of the first contacts we have with the nature surrounding us. However, it is important to understand that supplying food to wildlife can also at times have negative impacts on the health of wild birds. In order to limit the risks of spreading trichomonosis and other diseases in bird feeders, it is important to stay on the lookout for manifestations of diseases. Signs such as hypersalivation, regurgitation of seeds, presence of feathers and/or seeds stuck on the edge of the bill, swollen eyes, ruffled plumage or difficulty in breathing are an indication of illness. If a disease is suspected, the feeders should be removed for at least 2 weeks. In the case of trichomonosis outbreaks in late summer or fall, it is recommended to remove the feeders until the first frost. In order to minimize the risk of disease spreading, ensure a supply of healthy seeds by promoting small feeders that empty quickly and feeders with a roof to keep the food safe from the elements. It is also recommended to clean and disinfect bird feeders and baths at least twice a month. Although humans are not susceptible to this parasite, it is recommended to wear gloves when cleaning and to wash hands thoroughly afterwards due to the possible presence of other potentially pathogenic agents in feeder birds. (i.e. Salmonella, E. coli, Campylobacter). By minimizing the contamination of seeds by faeces, the use of silo feeders (instead of feeding trays) is preferable, especially during the summer.
Please report sick or dead birds to the Canadian Wildlife Health Cooperative. The nearest regional can be found on the following website: http://cwhc-rcsf.ca/.
For more information on this condition, please refer to the following factsheet: http://www.cwhc-rcsf.ca/docs/fact_sheets/Trich_Factsheet_EN.pdf
CWHC Quebec Regional Center