Is there any risk of illness from eating a banana?

Not as a rule, assuming the consumer doesn’t eat the peels. The peels  shield the underlying fruit from food-borne pathogens. However, it's advisable to wash bananas with cold water prior to peeling them to wash away any pathogens that may be on the skin.  Despite its protective peel, moisture and oxygen eventually take their toll on the banana, creating a breeding ground for spoilage bacteria (the kinds of germs that don't cause illness but can ruin the taste and look of food). At first, bananas will exhibit signs of overripeness, including a softened texture and blackening peel. Bananas are generally fine to eat in this condition. In fact, overripe bananas  are often used for baked items such as banana bread.
 
Split skins and oozing are signs of excessive spoilage. At this point, bananas are considered rotten and should be discarded. Do not use rotten bananas for baked items.
 
Source(s):
Healthlinkbc "Foods to Avoid for People at Risk of Food-borne Illness"