Useful links Learn what researchers discovered about disease transmission from eye disease research on the All About Birds Blog. In 2018, researchers studying the disease found that the pathogen that causes House Finch eye disease, Mycoplasma gallisepticum, is becoming stronger and more dangerous than earlier versions of the pathogen. Learn more on the FeederWatch blog. Learn how to distinguish House Finches from the similar Purple Finch and Cassin’s Finch on our Tricky Bird ID page. Learn more about House Finch biology on the All About Birds page.