Definition

Scarlet fever, also known scientifically as scarlatina, is an infectious disease triggered by the bacteria Streptococcus pyogenes. It is characterized by a widespread red rash, high fever, and sore throat.

While scarlet fever can affect individuals of any age, it predominantly impacts children aged 5 to 15. Approximately 80% of cases are found in children under 10 years old, with occurrences in those under 3 years being rare.

Antibiotics are effective in treating scarlet fever. Historically, this disease posed a significant threat to children. However, with the development of modern antibiotics, the severity and incidence of scarlet fever have markedly diminished.

Causes

Scarlet fever is induced by Streptococcus pyogenes, a member of the group A beta-hemolytic streptococcal bacteria. The bacteria is also the primary cause of tonsillitis (tonsil inflammation) and pharyngitis (throat inflammation). S. pyogenes can release toxins into the bloodstream, resulting in fever and red rashes.

Transmission of S. pyogenes from an infected individual's nose and throat to others can occur through several mechanisms:

• Droplets expelled by a patient's sneeze or cough
• Contact with objects contaminated by droplets from a patient’s sneeze or cough, followed by touching the nose or mouth without prior handwashing. Bacteria on the skin can also lead to skin infections.
• Direct contact with a wound of the skin infected with the bacteria
• Sharing utensils or equipment with individuals with scarlet fever

Untreated individuals can remain infectious for several weeks, even after their symptoms have subsided. The incubation period for S. pyogenes typically ranges from 2 to 4 days, the interval between exposure to the bacteria and the onset of symptoms.

Certain individuals may not exhibit a reaction to the toxins produced by S. pyogenes, thus becoming asymptomatic "carriers". This makes it challenging to know if one has been infected or not. Consequently, maintaining a healthy lifestyle and implementing preventive measures are crucial to preventing transmission.

Risk factor

The risk factors for contracting scarlet fever include:

• Children aged 5 to 15 years
• Direct contact with individuals infected with scarlet fever
• Frequenting or working in crowded environments, such as schools or childcare facilities

Symptoms

Symptoms of scarlet fever typically manifest 2 to 4 days following the bacterial infection. Scarlet fever symptoms include:

• Red rash. Resembling a sunburn and feeling rough to the touch, the rash often begins on the face or neck and then spreads to the arms and legs. When pressure is applied to the affected skin, it becomes pale.
• Sore throat. The throat appears very red and may have white or yellowish spots.
• Fever. Often accompanied by chills, with temperatures reaching 38.3 degrees Celsius or higher.
• Flushed face. The face appears red with a pale area around the mouth.
• Strawberry tongue. At the onset of the disease, the tongue appears red and bumpy with a white coating.
• Difficulty swallowing.
• Enlarged lymph nodes. The lymph nodes in the neck become swollen and painful when touched.
• Red lines in skin folds. The rash around the groin, armpits, elbows, knees, and neck appears redder than the surrounding skin.
• Nausea or vomiting.
• Abdominal pain.
• Decreased appetite.
• Headache.

The rash, a hallmark symptom of scarlet fever, generally appears 1 to 2 days after the onset of the fever. However, in some instances, the rash may appear up to 2 days before the fever and sore throat.

The rash and redness on the face and tongue typically persist for about a week. Once the rash fades, the affected skin usually peels for approximately six weeks.

Diagnosis

To diagnose scarlet fever, a doctor begins by inquiring about the patient's symptoms and medical history. This is followed by a physical examination, which includes examining the condition of the patient's tongue, throat, and tonsils, as well as assessing the lymph nodes and the presence of rashes on the body.

If the physical examination indicates a suspicion of scarlet fever, the physician will proceed with a diagnostic procedure known as a throat swab. This involves collecting a mucus sample by swabbing the back of the throat and tonsils. The sample is then analyzed in a laboratory to detect the presence of Streptococcus pyogenes.

Identifying S. pyogenes is crucial because several other conditions can present with similar signs and symptoms. If the bacteria are not found, the physician will consider alternative causes for the patient's symptoms.

Management

Treatment for scarlet fever aims to alleviate symptoms, prevent complications, and minimize the risk of disease transmission. The following treatments are commonly used:

Medications

Oral antibiotics, such as penicillin or amoxicillin taken by mouth, effectively treat scarlet fever. These are typically prescribed for 10 days. For patients allergic to penicillin, erythromycin may be used as an alternative antibiotic.

The fever generally subsides within 24 hours of starting antibiotics. Despite the improvement in symptoms, it is crucial to complete the full course of antibiotics to ensure complete recovery and prevent complications.

In addition to antibiotics, medications such as paracetamol or ibuprofen for fever and sore throat may provide symptomatic relief. If the rash causes itchiness, calamine lotion or antihistamine tablets may be prescribed.

Self-Care at Home

Several self-care treatments can help reduce discomfort and promote recovery, such as:

• Drink plenty of water to keep the throat moist and prevent dehydration
• Gargle with salt water to soothe a sore throat
• Use a humidifier to add moisture to the air, reducing throat irritation
• Consume throat lozenges in moderation
• Eat warm broths, like soup, to help relieve a sore throat
• Avoid irritants, such as cigarette smoke and harsh cleaning products, which can further irritate the throat

Complications

If scarlet fever remains untreated, the bacteria can spread and lead to infections in various parts of the body, such as the:

• Tonsil
• Lungs
• Skin
• Kidneys
• Blood
• Middle ear

In rare instances, scarlet fever could precipitate rheumatic fever, a severe condition affecting the heart, joints, nervous system, and skin.

Prevention

There is no vaccine available to prevent scarlet fever. Therefore, the best preventive strategy involves standard infection control measures, including:

• Washing hands regularly with soap and running water
• Avoid sharing eating utensils or food, especially with infected individuals
• Covering the mouth and nose when coughing or sneezing to reduce the spread of bacteria
• Washing eating utensils and toys with warm soapy water if your child has scarlet fever

When to see a doctor? 

Consult a healthcare provider if your child exhibits symptoms of scarlet fever, such as a sore throat, fever exceeding 38 degrees Celsius, swollen neck lymph nodes, and red rashes on the skin.

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