It is recorded in a wide range of bird species, including birds of prey and pigeons. but is most well-known for its effects on greenfinches due to the epidemic of 2005. It does not pose any risk to humans.
Most birds which have trichomonosis present with infected digestive systems and throats. The infected tissue makes swallowing very difficult and infected individuals often present with saliva or wet plumage around their bills, or old food that has been regurgitated present within plumage. In severe cases, the neck of the bird may also be very swollen. The lesions in the throat prevent birds from feeding, causing starvation and mortality. Birds with trichomonosis also show general signs of being unwell, being lethargic and having fluffed-up plumage.
Trichomonosis can be spread directly, through the feeding of young or of mates. Birds of prey can contract the disease by eating the remains of infected birds. It is also spread through indirect contact with other birds, when sharing food or water sources, especially those provided within garden habitats. Birds who are infected often regurgitate their food as they have difficulty swallowing, and this food is then eaten by other birds, and they too become infected.
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The disease was recognised as an outbreak during 2005, where an increasing number of passerines in the British Isles were found dead with infected tissue. These epidemics repeated in 2006 and 2007, normally during the late summer months and autumn (August/September through to November). Greenfinches and chaffinches were very badly affected, and breeding populations had reduced by over 500,000 birds by 2007. Each subsequent year has had some level of infection and trichomonosis is still present within the British Isles. The disease is also present in other countries within Europe, including Ireland, Germany, and the Netherlands.
Though greenfinches and chaffinches are well known for contracting this disease, other passerines have been known to contract the disease, including house sparrows, yellowhammer, goldfinches, and bullfinches to name a few. Since 2014, the proportion of trichomonosis cases has shifted from greenfinch cases reducing and chaffinch (and other passerine) cases rising.
Feeding and bathing stations for birds have always been a fantastic solution for providing additional resources to our garden birds. However, they have also been synonymous with disease transmission, as many birds gather in a small area and share food and water sources.
Our top tips to keep your garden bird’s safe are:
These tips will hopefully help keep your garden birds as safe as possible. If you suspect illness in your garden wildlife, you can report this to garden wildlife health at www.gardenwildlifehealth.org
Doyle, S., Reilly, M., De Waal, T., McMahon, B.J. (2022) Confirmation of avian trichomonosis among wild birds in Ireland. European Journal of Wildlife Research. 68(10): https://doi.org/10.1007/s10344-021-01558-3
Hanmer, H., Cunningham, A.A., John, S.K., Magregor, S.K., Robinson, R.A., Seilern-Moy, K., Siriwardena, G.M., Lawson, B. (2022) Habitat-use influences severe disease-mediated population declines in two of the most common garden bird species in Great Britain. Scientific Reports. 12(15055): https://doi.org/10.1038/s41598-022-18880-8
Lawson, B., Robinson, R.A., Neimanis, A., Handeland, K., Isomursu, M., Agren, E.O., Hamnes, I.S., Tyler, K.M., Chantrey, J., Hughes, L.A., Pennycott, T.W., Simpson, V.R., John, S.K., Peck, K.M., Toms, M.P., Bennett, M., Kirkwood, J.K., Cunningham, A.A. (2011) Evidence of Spread of the Emerging Infectious Disease, Finch Trichomonosis, by Migrating birds. EcoHealth. 8:143-153.
Lawson, B., Robinson, R.A., Colvile, K.M., Peck, K.M., Chantrey, J., Pennycott, T.W., Simpson, V.R., Toma, M.P., Cunningham, A.A. (2012) The emergence and spread of finch trichomonosis in the British Isles. Philosophical transactions of the Royal Society B: Biological Sciences. 367(1604): https://doi.org/10.1098/rstb.2012.0130
Lawson, B., Robinson, R.A., Toms, M.P., Risely, K., MacDonald, S., Cunningham, A.A. (2018) Health hazards to wild birds and risk factors associated with anthropogenic food provisioning. Philosophical transactions of the Royal Society B: Biological Sciences. 373(1745): https://doi.org/10.1098/rstb.2017.0091
Murray, M.H., Becker, D.J., Hall, R.J., Hernandez, S.M. (2016) Wildlife health and supplemental feeding: A review and management recommendations. Biological Conservation. 204(B): 163-174. Quillfeldt, P., Schumm, Y.R., Marek, C., Mader, V., Fischer, D., Marx, M. (2018) Prevalence and genotyping of Trichomonas infections in wild birds in central Germany. PLoS ONE. 13(8): e0200798.
https://doi.org/10.1371/journal.pone.0200798 Rijks, J.M., Laumen, A.A.G., Slaterus, R., Stahl, J., Gröne, A., Kik, M.L. (2019) Trichomonosis in Greenfinches (Chloris chloris) in the Netherlands 2009–2017: A Concealed Threat. Frontiers in Veterinary Science. 6(425):
https://doi.org/10.3389/fvets.2019.00425
Robinson, R.A., Lawson, B., Toms, M.P., Peck, K.M., Kirkwood, J.K., Chantrey, J., Clatworthy, I.R., Evans, A.D., Hughes, L.A., Hutchinson, O.C., John, S.K., Pennycott, T.W., Perkins, M.W., Rowley, P.S., Simpson, V.R., Tyler, K.M., Cunningham, A.A. (2010) Emerging Infectious Disease Leads to Rapid Population Declines of Common British Birds. PLOS One. 5(8): e12215. doi:10.1371/journal.pone.0012215
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