Birds and Trichomonas gallinae

The protozoan parasite T. gallinae infects certain species of birds and the disease is frequently fatal.

Sep 18, 2006

The deadly parasite Trichomonas gallinae can be spread among wild birds at feeders and bird baths. Bird watchers can avoid accidentally spreading this and other diseases.

Trichomonas gallinae is renowned for causing "canker" in domestic pigeons, and "frounce" in birds of prey. The disease can be mild and birds that survive appear to have some immunity to further infection; however, some strains cause a high death rate. Infected birds develop large yellowish masses in their mouths and crops, while in fatal cases; the parasite spreads to the liver and lungs.

T. gallinae does not survive long outside the host, so there are only a few ways that it can spread efficiently, particularly in the wild where birds have less frequent close contact with one another:

It can be passed from a mother to young in the nest when she feeds them regurgitated food.
It passes to birds of prey when they capture and eat smaller infected birds (and a sick bird is more likely to fall prey to a predator, making this more likely).
It lives in water for a brief period, so it can spread via bird baths and drinking water that birds frequent, and possibly via bird feeders where birds visit in quick succession.

A 2006 outbreak in the UK has killed finches and house sparrows - birds that frequent human gardens, bird baths and bird feeders. This may be an instance where carefully created backyard bird habitat has aided the spread of a virulent disease: bird feeders and bird baths may be the vehicles by which the parasite spreads so quickly with such devastating results. Here's what you can do to decrease the chances that your backyard bird habitat is spreading disease in birds:

Clean bird feeders and bird baths regularly, washing the feeders and adding fresh seed. Empty the water out of the bird bath, wash all surfaces, and allow it to dry thoroughly before adding fresh clean water.
Watch for birds that look ill. If you see sick birds at your feeders or in your bird bath, consider taking the feeders down for a few weeks and emptying the bird bath temporarily. Wild birds will forage more widely and find other water sources for drinking and bathing instead of all visiting at the same feeders and water.
If birds in your area are ill and you cannot take down feeders and empty bird baths, replace the water in the bird bath daily, and wipe down the exterior surfaces of bird feeders daily - with alcohol if possible (but don't let alcohol or any other disinfectant solution contaminate the seed).
Report sick birds to the appropriate local authorities.