They have meaning only to medical practitioners and health care managers willing to delude themselves that they can avoid shouldering responsibility for such infections in the absence of being confronted with a video or other visual record (and therefore, presumably unchallengeable) of the mechanism of infection.
Those with too much blood were sanguine. Those with too much phlegm were phlegmatic. Those with too much yellow bile were choleric, and those with too much black bile were melancholic. To be sanguine is to be courageous, hopeful and amorous. To be phlegmatic is to be calm and unemotional. To be melancholic is to be depressed, sleepless and irritable. To be choleric is to be easily angered and bad tempered.