Biological weapons have been used since ancient times. In the 16th century the Assyrians poisened the enemy wells with ergo, which was a kind of fungus that made the enemy delusional. Also during medieval times victims of the plague were flung over the castle walls with catapults to infect the people in the castle. Now there are more modern biological weapons in use. But since there was a treaty made that during warfare biological weapons werent being used, they are mostly used by terrorists.

http://en.wikipedia.org/wiki/Biological_warfare#History

In what other cultures were biological weapons used?

What other methods were used to transmit the disease?