Why Most Animal Viruses Never Become Human Pandemics

https://www.news-medical.net/health/Why-Most-Animal-Viruses-Never-Become-Human-Pandemics.aspx From receptor mismatch to risky human-animal interfaces, this article explains why spillover is common but true pandemic emergence remains rare. Humans are constantly exposed to animal viruses through farming, wildlife contact, and the environment; however, most animal viruses never reach pandemic potential. Successful spillover events are uncommon, as viruses must navigate complex biological, ecological, and evolutionary barriers before human-to-human transmission can occur. In the spillover cascade, an infected reservoir host must shed enough virus, the virus must survive or be carried to a susceptible human, and infection must then progress to onward transmission; failure at any one step can stop emergence.1,5 These barriers are also shaped by human behavior, land-use change, wildlife trade, farming systems, and other interfaces that determine how often people encounter infectious animals or contaminated environments.