Strep throat is a common bacterial infection caused by Streptococcus pyogenes, also known as Group A Streptococcus (GAS). It primarily affects the throat and tonsils, causing sudden discomfort. Unlike viral sore throats, strep throat requires antibiotic treatment to prevent serious health consequences. Leaving the infection untreated allows the bacteria to remain active, increasing the risk of both localized complications and systemic diseases affecting the heart, kidneys, and brain.
Acute Symptoms and Contagion Risk
Untreated strep infection results in the continuation of acute symptoms, which often begin abruptly. Patients typically experience a painful sore throat, sudden fever, and difficulty swallowing. Examination may reveal red, swollen tonsils, sometimes with white patches or streaks of pus. The lymph nodes in the neck may also become tender and swollen.
Without antibiotics, the bacteria can spread locally to nearby structures. This localized spread can result in complications such as an ear infection or a peritonsillar abscess, a painful collection of pus behind the tonsil that may require drainage. Furthermore, the infected person remains highly contagious for a prolonged period. Antibiotic treatment usually renders the patient non-contagious after about 24 hours, significantly reducing the risk of transmission.
Systemic Risks of Ignoring Treatment
The most serious reason for treating strep throat is the prevention of post-streptococcal sequelae. These are delayed complications that occur after the initial infection has passed. These systemic risks arise from a misdirected immune response, where the body’s antibodies, generated to fight the bacteria, mistakenly attack healthy tissues through a process called molecular mimicry.
Acute Rheumatic Fever (ARF)
The most dangerous complication is acute rheumatic fever (ARF), an inflammatory disease that develops typically two to four weeks after an untreated strep infection. ARF can affect the joints, skin, and brain. Its most damaging effect is on the heart, leading to rheumatic heart disease. The inflammation can permanently damage the heart valves, potentially resulting in chronic issues like heart failure or atrial fibrillation later in life.
Post-Streptococcal Glomerulonephritis (PSGN)
Another serious risk is post-streptococcal glomerulonephritis (PSGN), which is a type of kidney inflammation. This condition is caused by immune complexes—clumps of streptococcal antigens and the body’s antibodies—that become trapped in the filtering units of the kidneys. This immune-mediated inflammation can impair renal function, leading to symptoms like blood in the urine, facial swelling, and high blood pressure.
PANDAS
In children, an untreated strep infection can also trigger Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS). This condition is characterized by the sudden, dramatic onset or worsening of obsessive-compulsive disorder or tics following the infection. The autoimmune reaction is thought to target the basal ganglia in the brain, leading to these acute neurological symptoms.
Standard Diagnosis and Simple Treatment
Determining if a sore throat is caused by Group A Streptococcus requires a medical test, as symptoms alone cannot distinguish it from a viral infection. Diagnosis is typically confirmed using a rapid strep test for quick results, or a throat culture. The throat culture is more sensitive and is often used to confirm a negative rapid test result, especially in children.
Once strep throat is confirmed, treatment involves a short course of antibiotics, most commonly penicillin or amoxicillin. This medication is effective at eliminating the bacteria and is the most reliable way to prevent systemic complications like rheumatic fever and kidney damage.
Patients must complete the full 10-day course of medication, even if symptoms improve quickly, which often happens within a day or two. Stopping the medication early allows residual bacteria to survive, risking both a relapse of the infection and the development of post-streptococcal sequelae. Consulting a healthcare provider for any severe or persistent sore throat ensures proper diagnosis and preventative treatment.