Trichomonaisis is an infectious parasitic disease that affects band-tailed pigeons as well as other bird species like hawks and sparrows (Girard et al. 2014, a). Trichomonas is a protozoan, aka single celled, parasite that is spread through oral-oral contact (Cole, ND). The infective agent in trichonomaisis is the feeding trophozite form of the parasite. The bulk of cases are caused by Trichomonas gallinae , but Trichomonas stabileri can also result in the disease (Girard et al. 2014, a). Figure 1: Trophozoites (feeding form) of two species of trichomonas, a single celled parasite. (Girard et al., 2014, a) Birds can be infected or infect other birds by spreading the trophozoite through shared food and water sources, courtship behaviour known as “billing” (they sort of kiss), and ,sadly, when young are fed crop milk by their parents (Girard et al., 2014, a). Figure 2: A summary of trichomaisis transmission methods. Trichomonaisis is spread by oral-oral contact between birds. (Cole, ND) The disease results in foul smelling caseous (a fancy word for cheese-like) in the upper digestive tract, esophagus, trachea, or nasal area that kill the birds by blocking the passage of air or food, leading to suffocation and starvation (Girard et al. 2014, b). In severe infections the lesions may even spread from the nasal cavity to the brain (Girard et al. 2014, b). Infected birds are also quite lethargic and unsteady, Stromberg et al noted that infected birds fell over when they were forced to move (Stromberg et al., 2008). Other non-lesion symptoms are the accumulation of fluid in the crop and invasion of the liver and lungs (Cole, ND). Living in close quarters and sharing food can put birds at greater risk of catching or spreading the disease. You can prevent the spread of trichomoniasis by refilling and disinfecting feeders and birdbaths frequently and reporting any dead or dying birds to your local authorities (Cole, ND) Figure 3: A caseous trichomonaisis lesion in the mouth of a domestic rock dove. (Irish Wildlife Matters, ND) Major Death Events Outbreaks of trichomoniasis have occurred since at least 1945 and can involve thousands of birds(UC Davis, 2014). One notable epidemic occurred in central California during the winter of 2006-2007. Stromberg et al. surveyed the upper Caramel Valley and found a large number of dead birds from T. gallinae . They did a transect of 2.5 km and found 373 dead birds. They estimated that over a period of two months 43,059 birds died in the upper Caramel Valley alone (Stromberg et al., 2008). This is considered a conservative estimate of the number of deaths and it still is 6 times their original estimate (Stromberg et al. 2008).  Another outbreak occurred just this past winter in the mountains near San Diego and San Francisco. From mid-December 2014  to early February 2015 and estimated number of 5000- 10000 birds succumbed to trichomonaisis and that’s only counting urban areas (Palus, 2015). The most recent epidemic has been attributed to drought conditions forcing large numbers of birds to drink from small contaminated water sources (Palus, 2015) Interesting Facts 1) Trichomonaisis has been around for a very long time; T. rex skeletons have been found with evidence of caseous lesions on them (UC Davis, 2014) 2) The extinct passenger pigeon is quite closely related to band-tailed pigeons and likely shared its parasites. Trichomoniasis infections have been discussed as one of the factors responsible for the massive decline of passenger pigeons during the 1910’s (UD Davis, 2014) 3) It is considered an emerging pathogen because it was introduced to North America when rock doves (city pigeons) and eaurasian collared doves were brought over by European settlers as food (Cole, ND). This status makes it hard to know just how bad future outbreaks could be. 4) Don’t worry, this form of trichomoniasis cannot be spread to humans(Cole, ND)   References Cole, R. A. 2013. Chapter 25: Trichomoniasis. In: Field Manual of Wildlife Diseases: Birds (U.S. Geological Survey) eBook, pp 201-206. Available from http://www.nwhc.usgs.gov/publications/field_manual/ (A) Girard, Y. A., Rogers, K. H., Woods L. W., Chouicha, N., Miller, W. A., Johnson, C. A., 2014. Dual-pathogen etiology of avian trichomonosis in a declining band-tailed pigeon population.  Infection, Genetics and Evolution [Internet] 2014 [Cited 2015 Oct 30]; 24: 146-156. Available from http://www.sciencedirect.com.ezproxy.viu.ca/ (B) Girard, Y. A., Rogers, K. H. , Gerhold. R, Land, K. M., Lenaghan, S. C., Woods, L. W. , Haberkern, N , Hopper, M , Cann, J. D. , Johnsona, C. K., Trichomonas stableri n. sp., an agent of trichomonosis in Pacific Coast band-tailed pigeons (Patagioenas fasciata monilis). International Journal for Parasitology [Internet] 2014 [Cited 2015 Oct 30]; 1 (3): 32-40. Available from http://www.sciencedirect.com.ezproxy.viu.ca/ Kerlin, K. Die-offs of band-tailed pigeons connected to newly discovered parasite. [Internet]. 2014 Jul 14 [cited 2015 Oct 30]. UC Davis; News and Information. Available from http://news.ucdavis.edu/search/news_detail.lasso?id=10960 Palus, S. What’s Killing California’s Native Pigeons? [internet]. 2015 Feb 11 [cited 2015 Oct 31]. Audobon; Birds in the News. Available from https://www.audubon.org/news/whats-killing-californias-native-pigeons Pigeons: Diseases. [internet]. Not Dated [cited 2015 Oct 31]. Irish Wildlife Matters. Available from http://www.irishwildlifematters.ie/animals/pigeons-conditions.html Stomberg, M.R., Koenig, W.D., Walters, E. L., Schweisinger, J. 2008. The Wilson Journal of Ornithology [Internet] 2008 [cited 2015 Oct 30]; 120(3): 603-606. Available from http://www.jstor.org/stable/20456198?pq-origsite=summon&seq=2#page_scan_tab_contents