Update: “The virus is usually spread by migratory birds.” The word, generally-일반적으로, is missing from the beginning of the sentence. It should read: 일반적으로 그 바이러스는 철새로 인해 전염되요. [Thanks to reader David So for pointing that out^^]
Easy to Learn Korean (ETLK)
An Illustrated Guide to Korean Culture and Language
