Strep throat, caused by Streptococcus pyogenes (Group A Streptococcus or GAS), is a common bacterial infection affecting the throat and tonsils. Symptoms include sore throat, fever, and difficulty swallowing. Untreated, strep throat can lead to severe complications.
Local Spread and Abscess Formation
Untreated strep throat allows bacteria to spread beyond the initial infection site in the tonsils and pharynx, forming pus-filled pockets called abscesses. A common example is a peritonsillar abscess (quinsy), which develops near a tonsil.
Symptoms of a peritonsillar abscess include severe, often one-sided, throat pain, difficulty swallowing, and a muffled voice. Swelling of the tonsils and neck lymph nodes, fever, and chills are also common. These abscesses can obstruct the airway, making breathing difficult and potentially life-threatening. Infection can also extend into deeper neck spaces, leading to conditions like retropharyngeal abscess, which also compromises the airway. Rarely, infection can spread to the mastoid bone behind the ear, causing mastoiditis, which may lead to hearing loss or meningitis.
Acute Rheumatic Fever
Acute rheumatic fever (ARF) is a severe systemic complication of untreated strep throat. This inflammatory disease affects the heart, joints, brain, and skin. ARF is an autoimmune response where the immune system mistakenly attacks healthy cells after fighting strep bacteria. It typically emerges two to four weeks after infection.
The heart is involved in about half of ARF cases, causing carditis (inflammation of the heart). This can permanently damage heart valves, known as rheumatic heart disease (RHD), potentially leading to heart failure or irregular heart rhythms years later. Joint inflammation (arthritis) is another frequent manifestation, often affecting large joints like knees, ankles, and wrists with migrating pain and swelling.
ARF can also affect the nervous system, causing Sydenham chorea, characterized by involuntary, jerky movements of the hands, feet, and face. Emotional lability or inappropriate laughter may also occur. Skin manifestations, such as erythema marginatum (a non-itchy rash) and small, painless bumps, can also appear. Prompt antibiotic treatment of strep throat helps prevent ARF and its long-term heart damage.
Post-Streptococcal Glomerulonephritis
Post-streptococcal glomerulonephritis (PSGN) is another systemic complication of untreated strep infection. This condition involves inflammation of the kidney’s tiny filtering units, called glomeruli. Like ARF, PSGN is an immune-mediated response where the body’s immune system mistakenly attacks its own kidney tissues after fighting the strep bacteria. PSGN typically develops about 10 days after a strep throat infection.
Symptoms of PSGN include dark, tea-colored urine (due to blood) and swelling (edema), especially around the eyes, face, hands, and feet. High blood pressure and fatigue are also common. While many, particularly children, recover fully within weeks, a small number, more commonly adults, can develop long-term kidney damage or, rarely, kidney failure.
Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS)
Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS) is a neurological complication primarily affecting children after a strep infection. In PANDAS, the immune system produces antibodies that inadvertently target healthy brain cells, particularly in the basal ganglia. This autoimmune reaction leads to a sudden onset or worsening of neuropsychiatric symptoms.
Hallmark symptoms include the abrupt appearance of obsessive-compulsive disorder (OCD) and/or tic disorders. These symptoms can be intense, often accompanied by other behavioral and emotional changes. Children might experience severe anxiety, mood swings, irritability, or regression in developmental skills like handwriting or language. Other associated symptoms include fine motor difficulties, sleep disturbances, and sensory sensitivities. Recognizing the sudden, episodic nature of these symptoms with a recent strep infection is important for diagnosis and management.