Papilloma viruses in chaffinches give rise to warty growths - which have colloquially been called "tassel foot", and I think you would agree, looking at the photographs which have been kindly sent to me by David White, it is a very good descriptor.
Papilloma viruses in humans cause skin warts, which are very common but usually resolve spontaneously. In fact, I remember as a child, my Dad 'buying my warts from me' for a 5p (or maybe it was a sixpence?) - and magically they used to vanish! I think he just got his timing about right.
However, much more seriously, a number of 'high risk' strains have been linked to cancers such as cervical cancer. However, papillomaviruses are very specific to their host species - so the good news is that infected birds pose no threat to us humans - nor to any other wildlife in the garden. The bad news is - that the virus can be easily transmitted from one bird to another - which is why you often see 'mini outbreaks' - where two or three birds are affected at any one time - or there is a lingering presence in the garden for a few weeks/months.
The virus is spread by direct contact and also through indirect contact via feeder perches, tree branches etc. It goes without saying, therefore, that if you do see an infected bird in the garden, make extra sure that you clean your feeders and feeding stations thoroughly - more advice on this is given here.
Of course please also wear gloves when disinfecting and don't clean feeders in areas where you prepare food!
Since feeding stations, bird tables and bird baths are where birds hang out, it may be prudent to put these areas out of commission for a couple of weeks. I know it feels like a tough thing to do, but dispersing the birds for a period will reduce the risk of spread, and hopefully will resolve the issue more quickly...... no one likes to see poorly birds. Having used the word 'poorly' it is also true that in many cases they are bright and seem to be totally unaffected- just sporting thick 'Nory Batty' legs! Very often they develop immunity and recover. Sometimes they become very lame and lose a toe and occasionally chaffinches will become very debilitated and die - however this is not the norm.
I hope you have found this summary helpful. Please do feel free to drop me a line if you would like some advice and I am always grateful for any good photographs that you might take - it helps me build my photographic library (because I am a good vet but a hopeless photographer!).
Countryside Stewardship 
