In 2005 I started keeping bees. I never saw any disease or virus in my hives until the 2008/2009 season. The first disease I noted in the summer of 2008 was DWV, which is an acronym for Deformed Wing Virus. In the spring of 2009, I found another virus…Sac Brood Virus or SBV. During an inspecting of one hive in early May, I recognized a problem when I saw capped cells that were perforated and had jagged edges. Inside the cells were strange uncapped larvae, which looked like they had shrunken heads. Once the larvae is infected with the virus, it will die and eventually turn black. There is an image of this stage of the virus above along with some other photos of it.
When I found this virus, the only remedy I knew was to re-queen. In my case, re-queening did work and the symptoms went away within a few brood cycles. If the cure was from breaking the brood cycle or the new queen I am unsure, but I was glad to see the symptoms disappear.