NOSEMA-DISEASE, 55 



Whether a bee once infected ever recovers from the infection has 

 not yet been established definitely. From what is known of diseases 

 in man and animals one might expect recovery in a certain percent- 

 age of Nosema-infected bees. The data at hand indicate that 

 occasionally recovery does take place in the worker bee. This is 

 suggested by the fact that among the last few workers alive in a 

 colony, following a heavy infection resulting from an experimental 

 inoculation, some have been found upon examination to be only 

 slightly infected and still others to be free from infection. The 

 only conclusion that can be drawn at the present time on this point 

 is that if recovery from the infection ever takes place in the worker 

 bee the cases are comparatively rare. 



Whether the prognosis is as grave in the case of an infected queen 

 is not known. The facts at hand suggest that it probably is not. 

 In the writer's experience less than 50 per cent of the queens in 

 experimental colonies were found to be infected (Table I). Whether 

 they had been infected and had recovered was not determined. 

 The queens from colonies which had been inoculated from one to 

 three weeks were found to be free from infection, indicating that 

 infection was infrequent, at least within the period that workers 

 and drones show the greatest percentage of infection. 



Death from Nosema infection does not take place for some 

 time after infection. The length of time an infected worker hves 

 depends in a large measure upon the season of the year. During the 

 active bee season death takes place as a rule in less than one month 

 but in more than two weeks. During winter the disease may run 

 a course of two or three months or even more. Infected drones 

 die sooner than infected workers, whereas infected queens probably 

 live longer. This relation is to be expected since in healthy bees 

 a somewhat similar relation exists. It is quite hkely that the age 

 of the bee when infected is not a negligible factor in determining 

 the course of the disease. 



Finally it should be emphasized that the prognosis of Nosema 

 infection, as it occurs in the United States, is not nearly so unfavor- 

 able as has been reported for the Isle of Wight disease in England 

 and for Nosema infection in Bavaria, Germany. It is, however, 

 very similar to that of the infection as it has been reported from 

 Austraha (Price, 1910; Laidlow, 1911; and Beuhne, 1916). 



