Infectious diseases prevalent in humans and animals are caused by pathogens that once emerged from other animal hosts. In addition to these established infections, new infectious diseases periodically emerge. In extreme cases they may cause pandemics such as COVID-19; in other cases, dead-end infections or smaller epidemics result. Established diseases may also re-emerge, for example by extending geographically or by becoming more transmissible or more pathogenic. Disease emergence reflects dynamic balances and imbalances, within complex globally distributed ecosystems comprising humans, animals, pathogens, and the environment. Understanding these variables is a necessary step in controlling future devastating disease emergences. Understanding the dynamic balance and interplay between complex and global ecosystems comprising humans, animals, pathogens, and the environment provides perspectives on how we got to the COVID-19 pandemic.
【저자키워드】 COVID-19, pandemic, Virology, Infection, Epidemic, one health, zoonosis, medical history, disease ecology, Epizootic,