Strep throat is often accompanied by fever. Strep throat is one of many causes of inflammation of the pharynx (pharyngitis). Strep throat is a common cause of sore throat. Streptococcus spp. are the most common bacterial species to cause strep throat (15%-30% of pharyngitis in children and about 5 to 10% in adults). Strep throat is contagious for about 2-3 weeks in individuals that do not take antibiotics. However, individuals that take antibiotics for strep throat usually are no longer contagious about 24 hours after initiating antibiotic therapy.