infectiousness

noun
1
the ability of a disease to be passed easily from one person to another, especially through air or water
سرایت پذیری, قابلیت انتقال, مسری بودن
2
the fact that somebody's actions or feelings cause other people to do or feel the same
انتقال‌پذیری, سرایت‌پذیری
the infectiousness of his humour