What is scarlet fever?
Scarlet fever, or scarlatina, is a bacterial infection that typically affects children and teenagers. It’s caused by a type of bacteria called group A Streptococcus, or group A strep. If the bacteria attack your throat, it’s called strep. If it gives you a skin rash, it's diagnosed as scarlet fever.
Only 10% of people who are exposed to group A strep develop scarlet fever. The bacteria creates a toxin that reacts with your skin, resulting in a scarlet-colored rash that has the texture of sandpaper.
Symptoms of scarlet fever
When making a diagnosis, your doctor will pay more attention to the texture of the rash instead of the color. The rash can last for a week or even longer. As it fades, the skin on your fingertips, toes, and groin area may start to peel.
Other symptoms of scarlet fever include:
- Muscle aches
- Sore throat and a swollen tongue
- Red color in the creases of your armpit and groin
- Stomach pain
Scarlet fever is contagious. Once you're infected, it only takes one or two days to start developing symptoms.
Causes of scarlet fever
Group A strep live in your nose and throat and are easily passed to other people. Not everyone who is infected has symptoms. The bacteria is spread through small respiratory drops that are released into the air when you cough or sneeze.
Infection occurs when you:
- Inhale the droplets
- Touch a surface with droplets on it, then touch your mouth or nose
- Share drinks, food, or utensils with someone who is sick
- Touch sores on the skin
In rare cases, scarlet fever or strep is spread through food that isn't properly handled.
When to see the doctor for scarlet fever
If you or someone in your family suddenly develops a fever, sore throat, swollen glands, or a red rash, call your doctor. This is especially important if you know someone who recently had strep. These infections are easily spread at school, in daycare, or in the office.
Diagnosing scarlet fever
Your doctor will likely start with a rapid strep test, which involves swabbing your throat, then testing it. The results will show if bacteria from group A strep is causing your illness. If the result is positive, you'll be prescribed antibiotics.
If test results come back negative but your doctor still suspects you have scarlet fever, they will take a throat culture swab and send it to a lab for further analysis. The throat culture takes longer, but once the bacteria are given a chance to grow and multiply, a culture can identify infections the rapid strep test might miss.
Treatments for scarlet fever
Scarlet fever is treated with antibiotics. If you aren't allergic to penicillin, you'll likely be prescribed penicillin or amoxicillin. People who have a penicillin allergy will take a different course of antibiotics.
While taking antibiotics, you can alleviate symptoms by:
- Taking an over-the-counter (OTC) painkiller, like acetaminophen or ibuprofen
- Gargling with warm salt water to soothe a sore throat
- Using a cool-mist humidifier to make breathing easier
- Consuming more liquids, including warm soups and cold drinks, to help you swallow solid foods
Long-term effects of scarlet fever
Scarlet fever is no longer contagious after you've been on antibiotics for 24 hours. The rash generally fades within a week, but can linger for up to two weeks in some patients.
While rare, scarlet fever does have some complications if the strep bacteria spreads to other parts of the body. Complications include:
- Swollen lymph nodes in the neck
- Sinus, skin, and ear infections
- Pockets of pus, or abscesses, around your tonsils
- Rheumatic fever, which affects your heart
- Pneumonia, a lung infection
- Arthritis, or joint inflammation
- Post-streptococcal glomerulonephritis, a kidney disease
Taking antibiotics can prevent most of these health problems.
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Harvard Medical School: "Scarlet Fever."
Institute for Quality and Efficiency in Health Care (IQWiG): "Scarlet fever: Overview."
Medline Plus: "Scarlet fever."
National Center for Biotechnology Information: "Scarlet Fever."