as mentioned before, there are multiple stages of the disease and the affected hosts will have varying levels of speed, strength and stamina depending on how recent their transformation was.
regardless of the stage, there is one surefire way to incapacitate the infected threat: destroying or significantly damaging the brain.
the infected seem to be unimpeded by blood loss, and will continue to operate even when significantly injured, although removing or disabling limbs will render those limbs unusable. decapitating the infected will render it unable to move, but it will still exhibit brain activity and is capable of infecting others for a short while longer.
severe blunt force trauma, stab wounds and bullet wounds to the brain, especially with stronger or higher caliber weapons, is the best course of action against the infected. ranged weapons are a safer option due to the speed and strength capabilities of an early stage infected, so carrying a bow or gun is ideal. a knife is only to be used if you can reliably hit the brain via a known weak point in the skull.
the infected are also vulnerable to fire and electrocution, the latter of which makes electric fencing useful. extremely loud noises can cause confusion and pain for the infected. outrunning an early stage infected is not advised, as even if you are a fast runner, the infected have heightened stamina and could outlast the majority of people. you can escape an infected by hiding in something relatively secure/sturdy, or by climbing/swimming out of range of the infected.
depending on the location of the bite, survival may be possible.
a bite on the hands or feet has the highest survival probability due to their distance from the brain. if an amputation takes place within a few hours after the bite, survival is highly likely.
a bite on the arms or legs has a decently high survival probablility if an amputation takes place within 1-2 hours after being bit.
a bite to the torso, neck or head has an extremely low survival rate, due to a lack of ability to amputate. full infection will occur within a few hours.
there is no known cure to the disease, so amputation is the best chance you have at survival if bitten. always amputate at least a couple of inches from the site, more depending on the amount of time passed.
as soon as the symptoms start to present, it's too late. the victim needs to be killed to prevent further spread.