If left untreated, Strep can survive in the body for many weeks, and it will remain contagious for as long as it survives. The bacteria is not infectious outside of the body when it has died, but is able to survive for around two weeks in damp, moist environments.
However if treated with antibiotics, strep throat and its symptoms will not be contagious after 24 hours, as antibacterial medication is very efficient against this particular disease. Therefore, it is very important to see a doctor as soon as symptoms start, and try to keep away from family and friends who could become infected.
The Strep Throat infection can take five days to take hold , and symptoms in patients won't be obvious for a further 48 hours. During this time, patients will not know that they are infectious or that they are about to be ill.