Answer:
I can't write that well, but here's my personal answer.
Groups that seek national purity, such as the Nazis, want to maintain the purity of their population based on race, ethnicity, gender, etc.
For example, the Nazis sought racial purity- they wanted to keep the German people as pure "Germans," they did not want to have the Jews contaminating their pure German population.
In a sense, the Nazis saw the Jews as a disease that needed to be eliminated. The Jewish genes would mix with the German genes and pollute the entire population. It was for the sake of "health" to kill the Jews.
To achieve "national purity," a group similar to the Nazis would likely eliminate other groups to remove their genes from the overall human gene pool. In a way, such actions are for the sake of health.
I mean, if we killed all the elderly, disabled, and genetically defective people in the world, wouldn't the world be a better place? Their genes will not be able to affect other people, right? Theoretically, yes...
...but on so many moral, ethical, and physical levels, so much no.
Why would they use a health symbol for their representation of national purity? These groups try to use the premise of "health" as an excuse for their horrible ideals of national purity. They believe that national purity is what determines the "health" of the individual and of human society. It's the idea that the purer you are, the more healthy you are. I can't stress this enough: wrong on so many levels.
Groups like the Nazis use health symbols to show that national purity is, in some demented form, a measurement of someone's health. They kill other people because these individuals are a disease that needs to be eradicated. Their impurity contaminates the purity of the whole.
Got a bit off track, but I think you get the idea. Hope this helps!
