Technical Abstract: N. ceranae is now present in a high proportion of American honey bee hives. It has been implicated in colony mortality, especially in conjunction with parasites and other pathogens. PCR is the method of choice to detect light infections and to distinguish between species. It is highly sensitive and accurate, and allows the detection of vegetative forms of Nosema where spores are not evident. However, the PCR method is expensive and laborious. It cannot distinguish between the spore form and the vegetative form of Nosema, nor between viable and dead spores. Inexpensive and rapid methods for detection and evaluation of Nosema infections would be valuable for routine diagnosis and scientific studies. Hence, the development of techniques in light microscopy and antibody tests described in this chapter will be beneficial to all concerned with this disease.