There are many categories of agents that cause communicable diseases (I'll give an example of a few:)

Viruses, such as Rhinovirus which causes the common cold, or the Herpes Simplex Virus Type-1 which causes the cold sores that some people get on their lips.

Bacteria, such as Staphylococcus aureus … Read more

The Aztec emperor at the time of the arrival of Hernán Cortés in México (1519) was Moctezuma Ilhuicamina, the son of Moctezuma Xocoyotzin (both are known in English as " Montezuma".)

The last emperor was Cuauhtémoc whose name in Náhuatl or Meshica (the language of the Aztecs, still spoken by a few hundreds of thousands in … Read more