Diagnosis
Diagnosis is dependent on microscopic examination of the ventricular (midgut) content and/or fecal matter or on PCR analysis of infected tissue. No specific outward sign of disease may be present, although in dissections the ventriculus often appears whitish and swollen in late stages of infection. The disease is easily detected in samples of whole bees macerated in water. The fluid is examined under a light microscope at 250–500 x magnification where the characteristic Nosema spores can be observed. Though the spores of N. apis and N. ceranae have slight morphological and ultrastructural differences, they cannot be reliably differentiated via light microscopy. PCR analysis or electron microscopy of spores are the only reliable ways to differentiate between the two types of Nosema infection, given genetic variation and variation in the number of sporular polar filament coils between the two species.
Read more about this topic: Nosema Apis