A patient has been diagnosed with strep throat. The nurse is aware that without treatment, which complication may occur?

A. Rubella: Rubella is a viral infection caused by the rubella virus, not a complication of untreated strep throat. It is unrelated to Group A Streptococcus (GAS) infection and is prevented through vaccination. B. Leukoplakia: Leukoplakia is a condition characterized by white patches on the mucous membranes, often associated with chronic irritation or tobacco use. It is not a complication of streptococcal pharyngitis. C. Rheumatic fever: Untreated streptococcal throat infections caused by Group A Streptococcus can lead to rheumatic fever, an inflammatory disease affecting the heart, joints, skin, and brain. This autoimmune response can result in rheumatic heart disease, which may cause permanent cardiac damage. D. Scarlet fever: While scarlet fever can develop from strep throat, it is not a long-term complication but rather an acute reaction to the streptococcal toxin. The more serious complication of untreated strep throat is rheumatic fever, which can have lasting consequences, particularly for the heart.