Diseases will always be an issue and can affect any living form even they do produce a viable alternative to many of our illnesses. Honeybees and their larvae are affected by many diseases caused by bacteria, fungi and viruses.
Research has established a link between certain bee viruses, Varroa and colony decline. The mite can transmit some viruses within the colony and increase the rate of infection compared to hives that are mite-free. Some mite-transmitted viruses, such as deformed wing virus, acute paralysis virus, slow paralysis virus and cloudy wing virus, weaken honeybee colonies by reducing the longevity of adult honeybees. This affects their efficacy as pollinators and nectar gathers. Adult honeybees that develop in late summer will normally overwinter in the hive and survive until the spring. Those weakened by viruses die prematurely. A colony that appears strong in late summer can die out over winter or is reduced by the spring to a greatly weakened and non-viable colony.