Looking at it from the perspective of treatment options, the only treatment option is Fumagillin, which is not allowed in most countries. In view of the fact that by the end of the year, U.S. beekeepers will not be permitted to use Terramycin and Tylosin, due to the concern about antibiotic contamination and possible resistant bacteria in humans, using Fumagillin seems ill advised though one wonders why it was not included in the prohibition.

Further, it is not clear that Nosema can be accurately diagnosed nor is it directly associated with colony decline, at least in Virginia. The experiments Fischer cited showed impact in lab studies on individual bees. This does not equate with impact in the field. The whole problem with lab tests vs. field tests is "what does this really mean?"

Traver and Fell write:

> The survey data from our study indicate that approximately 70% of colonies in Virginia are infected with N. ceranae.

> The diagnosis of N. ceranae infected colonies in the field is difficult due to a lack of outward signs of infection. Our studies also show that colony strength is not a good indicator of infection. No differences were found between beekeeper ratings of colony strength and the level of infection; both strong and moderate strength colonies were heavily infected, often to a greater extent than weak colonies. 

> Additionally, the use of spore counts was not a reliable indicator of disease prevalence with N. ceranae. Over 50% of the colonies diagnosed as negative using a spore analysis were positive for N. ceranae using qPCR. When spores were present, spore counts were not well correlated with qPCR results.

Since most colonies have it and many of these same colonies were categorized as strong, it would be difficult to impute from the above that all colonies need to be fed Fumagillin, which is highly toxic to humans. Finally, there is evidence that it doesn't even work:

Huang, Wei-Fone; Leellen Solter; Peter Yau; Brian Imai (7 March 2013). Schneider, David S, ed. "Nosema ceranae Escapes Fumagillin Control in Honey Bees". PLoS Pathogens 9 (3): e1003185. doi:10.1371/journal.ppat.1003185.

PLB

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