Clinical
Strep throat: symptoms, causes, and how it is diagnosed
A plain guide to group A Streptococcus: what it is, how it spreads, why early diagnosis matters, and how testing is changing.
What a strep throat infection is
Strep throat occurs when the throat and tonsils are infected with group A Streptococcus. It is a major cause of pharyngitis and typically brings sudden throat pain, fever, and difficulty swallowing. Unlike a viral sore throat, it requires antibiotic treatment, which is exactly why accurate diagnosis matters.
More than 15 million outpatient visits a year in the United States are linked to sore throat complaints, and many patients still receive the wrong treatment because of the limits of the tests in common use.
How it spreads
Group A Streptococcus spreads through respiratory droplets when an infected person coughs, sneezes, or talks, and through shared utensils, drinks, and frequently touched surfaces. Schools and daycare centres raise the risk simply because of how much close contact happens there.
What to look for
Sudden and severe sore throat, pain on swallowing, fever, and swollen lymph nodes. Strep throat typically does not cause a cough or a runny nose. If those are present, a viral infection is more likely.
Why early diagnosis matters
Untreated strep throat can lead to rheumatic fever, kidney inflammation, and ear and sinus infections. Early and accurate diagnosis also keeps antibiotics for the patients who need them, which limits both side effects and resistance.
How it is diagnosed today
Providers combine symptom evaluation with rapid antigen detection tests and throat cultures, both of which require a throat swab. These have been in use for decades, but they can produce false negatives or need laboratory confirmation. Saliva-based qPCR offers a non-invasive alternative that improves comfort and returns a result far sooner.
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