Natural infection by Nosema ceranae causes similar lesions as in experimentally infected caged-worker honey bees (Apis mellifera)

In this report, the pathological features observed in honey bees naturally infected with the microsporidium Nosema ceranae throughout a year are described. The lesions produced under natural conditions are similar to those observed in experimentally caged worker honey bees. N. ceranae is able to reproduce inside epithelial cells and multiply all through the year causing lesions in host-cells, characterized by a progressive and irreversible destruction of the epithelial layer of the ventriculus, which can lead to major negative repercussions on the normal process of digestion, with critical consequences on honey bee and colony viability. It is remarkable that factors such as continuous access to fresh pollen around the apiary or temperature and humidity variations throughout the year in different seasons did not apparently influence the development of the endogenous cycle of this parasite under field conditions.