The Microbial Threshold for Illness: Unveiling the Magic Number
The number of microbes required to make us sick varies depending on the pathogen and is known as the infectious dose. While some pathogens require a large number of organisms to start an infection, others, like norovirus, have an incredibly low infectious dose, making them highly transmissible. Determining infectious doses is challenging and often relies on animal models or observational studies. The concept of viral load, which measures the number of replicating organisms within a host, is related but distinct from infectious dose. Understanding infectious doses can help explain why certain pathogens are more easily transmissible than others.
