Hi Celsiana...Cornell is studying conjunctivitis in House finches and Goldfinches. I haven't figured out how to add a link to this message board yet, so the web site is www.birds.cornell.edu
Then just look for House Finch Disease Survey. I don't think the disease spreads from the finches to other birds. At least, I haven't found any reference to that. I had several finches with bad eyes two years ago, but none now. I think it just ran its course. It was a pitiful thing to see and know I could do nothing to help. The statistics from the Survey show that its dying down in some parts of the country and flaring up in others. I think the harsh winter we had two years ago probably did in the infected birds I was seeing. Poor things were so defenseless.
I looked thru my field guides for your yellow finch...I found one called a Lesser Goldfinch, but they're usually further west than Michigan. I love eNature.com for researching birds and listening to their songs. I wonder if your bird might be some kind of a warbler. Lots of yellow in that family. Good luck...it would drive me nuts till I found out what it was... <img src="/images/graemlins/smile.gif" alt="" />