Answer:
The 21st century has already been marked by major epidemics. Old diseases - cholera, plague and yellow fever - have returned, and new ones have emerged - SARS, pandemic influenza, MERS, Ebola and Zika. These epidemics and their impact on global public health have convinced the world's governments of the need for a collective and coordinated defense against emerging public health threats and accelerated the revision of the International Health Regulations (2005), entered into force in 2007.
Step-by-step explanation: