The birds most susceptible to trichomoniasis are Greenfinches and Chaffinches, though other species (particularly finch species) may also be affected.

The parasite makes it difficult for birds to eat, initially leading to difficulty swallowing but as birds struggle to eat they will become colder and less energetic, with symptoms worsening over several days. Infected birds will be inclined to fluff up their feathers more and be slower than other birds to fly away when disturbed. They often have bits of food stuck around their bill. Unfortunately, the bird will eventually succumb to the infection, so the best thing to do is minimise the risk of other birds getting sick.

See below for an image of a Greenfinch with noticeable signs of trichomoniasis.