Is Strep Throat Contagious?

Group A streptococcus bacteria cause strep throat, a contagious throat infection. These bacteria can be spread from one individual to another through direct contact with infected fluids, or by touching a contaminated surface. Once someone has become infected with these bacteria, it takes about two to four days before symptoms appear.

Strep Throat -- Is It Contagious?

Strep throat is a throat infection caused by group A streptococcus bacteria (also known as GAS or Streptococcus pyogenes).
 
Many people wonder if this infection is contagious. The answer is yes -- the bacteria that cause strep throat can be spread between individuals. This transmission normally occurs through direct contact with infected substances (mucus, nasal discharge, saliva) or by touching shared items or surfaces that have come into contact with someone else's infected fluids.
 
Strep throat can affect anyone. However, these infections tend to occur more often in:
 
  • Children between the ages of 5 and 15
  • Certain settings, such as schools, dormitories, households, and daycare centers
  • Certain times of the year (late fall, winter, and early spring).
     
Once someone becomes infected with group A streptococcus, they do not immediately have any signs or symptoms of strep throat; it takes about two to four days on average for symptoms to start. This period between transmission and the beginning of symptoms is called the "strep throat incubation period."
 

How Long Is Strep Throat Contagious?

Once infected, a person who goes untreated can pass the infection to others for up to four weeks, even if they don't have symptoms. If they do receive antibiotics, after 24 hours, the person will no longer spread the bacteria to others.
 
Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD
Last updated/reviewed:
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