"Infectious diseases are one of the leading causes of death around the world. According to the WHO, three of the top 10 causes of death worldwide in 2019 were infectious diseases These diseases are caused by microorganisms such as viruses, bacteria, fungi, and parasites. Some infectious diseases spread by person-to-person contact, while others spread through contaminated food or water or by contact with an infectious insect or animal. Public health systems protect people and communities by preventing disease, encouraging and distributing vaccines, and promoting healthy living"-- Provided by publisher.