Infectious diseases are disorders that are often caused by organisms such as bacteria, viruses, fungi or parasites. Organisms live in our bodies and are typically harmless, however, certain conditions may cause the organisms to spread infectious diseases that can be spread from person to person.
Some infectious diseases can be spread by insects or animals.
These health threats are called zoonotic infectious diseases, and recent outbreaks include COVID-19 and Ebola.
“In the age of COVID-19, it is understandable that many people may not realize how many outbreaks of other infectious diseases are caused by complex, intertwined ecological and socioeconomic conditions,” lead author Patrick Stephens, an associate research professor at the University of Georgia’s Odum School of Ecology in Athens says.
His team analyzed 4,400 zoonotic disease outbreaks worldwide since 1974. They identified the 100 largest, all of which infected thousands to hundreds of thousands of people. These were compared with 200 outbreaks that included 43 or fewer cases.
Causes of infectious diseases
Contaminated water is the leading cause of large-scale outbreaks of infectious diseases that can be transmitted from animals to people, researchers say.
Water contamination was the most common cause of large outbreaks and the second most common cause of smaller ones. Examples of these water-associated diseases include hepatitis E, typhoid and dysentery.
Protect yourself from waterborne illnesses with the following tips from the CDC: