Hi all
I just read a new study done in France which sampled colonies to see what infectious agents (IA) were present. All colonies had IAs and none of them correlated directly with mortality. In other words, the presence of any given IA does not therefore lead to the death of that colony. For example, AFB and Nosema c. were detected in 99% of the apiaries. In fact, these IAs were present in 66% and 71% of colonies, respectively. But the authors state plainly:

> No specific pattern could be highlighted when comparing the prevalence of the IA between dying and surviving colonies. No significant relation could thus be established between a given agent and the death of colonies during or at the end of the study.

> According to our results, apiaries and colonies appear to be important reservoirs of infection, often infected by many different categories of agents (bacteria, microsporidia, viruses), but rarely affected by severe troubles such as depopulation, well-known clinical signs of major diseases, etc., We therefore gave them the status of asymptomatic carriers.

> These infectious agents are commonly present in the bee without necessarily showing clinical signs, until an additional factor is added, causing the onset of clinical signs by exceeding the bees’ tolerance level.

This jibes with the notion that while IAs are the ultimate causative agents of disease, hence the need for sanitation; nevertheless, a healthy individual is fully capable of bearing a significant load of pathogens without presenting overt symptoms of a particular disease.

SOURCE:
Prevalence of 12 infectious agents in field colonies of 18 apiaries in western France
Revue Méd. Vét., 2013, 164, 12, 577-582

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