Fringilla papillomavirus

The British bird population is prone to a whole manner of different diseases, infections and parasites. The impact of infectious diseases on our bird populations is something of considerable interest to me as a naturalist and something I feel needs more attention. Fringilla papillomavirus is a disease which is quite common amongst chaffinch in Britain and is regularly and incorrectly referred to as bumblefoot which is a bacterial infection caused by an entirely different organism. F.papillomavirus causes what is known as viral papillomas or warts for want a better word. This disease affects all ages of chaffinch of both sexes and to a lesser extent brambling. We tend to find it clustered within populations and localities, typically affecting a small portion of the population.
The disease consists of a warty covering of the foot and leg (tarsometatarsus). This is typically a mass of irregularly shaped growths containing nodules and fissures (see below) made up of excessive growth of keratinised layers of skin. Affected birds are usually in good health although they may struggle to walk on one foot and often hop. There is little evidence that is has significant affects on populations at local or national levels.



Warty growths on the foot typical of the infection, here seen in a male chaffinch

Whilst the outcome of the disease on individuals is still largely unclear it is thought that in severe cases birds die through incapacitation of the disease after loss of condition. Birds with this disease are also thought to be more susceptible to other secondary infections. Currently not enough is known about the way or efficiency in which the disease spreads but the fact that it occurs in clusters is suggestive that it spreads between individuals coming into contact with an infected bird. As with more serious diseases like Trichomoniasis and Salmonellois maintaining good levels of hygiene such as regular cleaning of feeders may help reduce the impacts of the disease on the local population.