Most of the important work on viruses was already completed when Bailey and Ball published the following in 1999. In the following you will note several key points. Viruses are ever present and usually do not cause illness. Healthy colonies build up and thrive despite them, but they may become critical if hives are employed for commercial beekeeping where they are loaded on trucks, moved about and kept in high concentrations (holding yards, etc.) 

Finally, he states that while there may exist locally distinct viruses, they will not remain so in today's global economy. Isolationism and protectionism are not therefore justified, given the circumstances in the real world. (Results naturally will vary in the hypothetical world, where everything works out fine in the end).

> Isolation and characterization of bee viruses began in the 1960s, with work on two diseases, sacbrood and paralysis, which have striking symptoms. Sacbrood, although extremely common in Britain, was, until the virus was isolated, dismissed there as a genetic disorder. Similarly, paralysis was ascribed to independent, but accompanying and very common, well known parasites, especially microsporidia and mites, which do not cause any overt symptoms. 
> 
> Many, if not all, of the viruses of bees persist in the population as slight or inapparent infections, but under certain circumstances they begin to multiply within individuals and spread between them, leading to outbreaks of disease.
> 
> Although almost all of the viruses of bees have been shown to be widespread and to shorten the lives of individuals, their effects under most circumstances are not striking. Indeed, the persistence of a number of distinct and occasionally virulent viruses in apparently healthy, perennial colonies emphasizes the powerful innate ability of bees to resist their multiplication and spread. 
> 
> This natural propensity is most evident when colonies of bees are allowed to develop and undertake their normal activities unhindered - an ideal which is increasingly difficult to attain with the demands of modern intensive beekeeping, particularly migratory and pollination work. 
> 
> Some honey bee viruses may still be localized but their ability to persist as inapparent infections, together with the continued and increasingly rapid international trade in bees seems to make their ultimate distribution worldwide inevitable.

from
HONEY BEE VIRUSES
Brenda V Ball, and Leslie Bailey
Copyright © 1999 Academic Press

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