Hah! I LOVED your title! And you know what? This isn't the first time prejudice/psychology/politics has been referred to as a biological disease. You may not care too much for military history, but this is good - I promise.
When Germany was weakening during WWI, they wanted to destroy Russia on the Eastern Front so they could concentrate on France. So they found a guy named Vladimir Illyich Ulyanov - also known as Lenin - in Austria, bundled him up in a secret train, and smuggled him across the lines into Russia.
Lenin did as Germany hoped and began a revolution in Russia, ending in the October Revolution in 1917, the birth of the Soviet Union, and the end of the war on the eastern front.
Problem is, there was quite a bit of fraternization across the lines, so just as Lenin's communist propaganda flourished among the Russian troops, it also began to spread among the German troops, even to the point where the German generals began to isolate them from other German troops in order to keep the propaganda - the infection, if you will - from spreading. But spread it did, and (along with dwindling supplies, the 1918 H1N1 flu, and the growing strength of the Allies) it played a significant part in Germany's loss by weakening the morale of the German Army.
In this way, communist propaganda - much like white supremacist propaganda - was spread first as a biological weapon, but then even as the Germans tried to isolate it as they would any other virulent disease, it spread among the population with disastrous effect.
But as far as I know, the Germans didn't use contact tracing :)