Answer:
The factors that favour the spread of infectious diseases around the world are :
Adaptation of microorganisms: The infectious microorganisms being able to adapt to different living conditions.
Globalization: With travel being made a lot easier in today's world, millions of people travel from one place to another each day. These travellers carry microorganisms from one place to another along with them. Hence, favouring the spread of infectious diseases.
Deforestation: Deforestation is also one of the ways that spread infections. A place in which deforestation has occurred is subjected to increased number of microorganisms from the previous animals and plants living in that area. When people come to live in this area, they are most likely to get infected by these microorganisms.
Exchange of livestock: In today's world it is common to trade livestock animals. These animals carry vectors for infectious diseases in them.