Scarlet fever

Methods for diagnosis

Scarlet fever is usually diagnosed by looking at symptoms, particularly if a rash is present. Your doctor may also look closely at the throat and glands.

A throat culture may also be performed to look for Streptococcus bacteria. During this procedure, the throat and tonsils are gently rubbed with a sterile cotton swab. This swab is then processed to confirm the diagnosis. In some cases, a blood sample may also be collected to rule out other potential causes of rash and sore throat.

Types of treatment

Treatments for scarlet fever aim to shorten the illness, limit the spread of infection and reduce the risk of complications. Your options include:

Self care

To relieve pain and fever, your doctor may suggest over-the-counter medications, such as acetaminophen and ibuprofen. Similarly, calamine lotion or an over-the-counter oral antihistamine medication may be recommended to reduce itching.

For an associated sore throat, saltwater gargles, soothing liquids or medicated lozenges that cool or numb the throat may be helpful. Plenty of water and rest can help the immune system to naturally fight the bacterial infection.

Medications

Although the symptoms of scarlet fever are usually mild and will clear on their own within 7-10 days, Streptococcus bacteria are likely to remain if the infection is not treated. To reduce the risk of complications or further spread of infection, antibiotics are prescribed when Streptococcus bacteria infection has been confirmed.

The most common antibiotics for scarlet fever are oral penicillin or amoxicillin over a course of 10 days. Less frequently, erythromycin may be prescribed if an allergy to penicillin exists. Once treatment begins, symptoms generally start to ease within a day or two. Children can usually return to school 24 hours after starting antibiotic treatment.

Complications

Although most cases of scarlet fever are successfully cured with antibiotics, complications can arise when the condition is left untreated. Possible complications include:

Spread of infection

If left untreated, Streptococcus infection can spread to the following areas:

• Tonsils (tonsillitis or quinsy, a type of abscess that forms behind the tonsil);
• Middle ear (middle ear infection);
• Sinuses (sinusitis);
• Bones (osteomyelitis);
• Lungs (pneumonia);
• Blood (sepsis), and;
• Brain (meningitis).

Some signs that the infection has spread include fever, increased heart rate, rapid breathing, vomiting and confusion. Seek urgent medical attention if any of these symptoms occur.

Rheumatic fever

In rare cases, group A Streptococcus bacteria can cause ongoing activation of the body's immune system, weeks after scarlet fever has cleared. This subsequent condition, known as rheumatic fever, leads to inflammation in other areas of the body, including the joints, skin, heart and brain. Rheumatic fever often causes lasting damage to the heart valves (endocarditis), but not to other affected areas of the body.

Kidney disease

In a similar way to rheumatic fever, an ongoing immune response to group A Streptococcus bacteria can lead to inflammation of the kidneys, known as post-streptococcal glomerulonephritis. Again, it generally occurs a few weeks after scarlet fever has cleared.

Symptoms of post-streptococcal glomerulonephritis include blood in the urine, a puffy face and swollen feet and ankles. However, it usually clears on its own within a week without causing any lasting damage. For this reason, this condition is considered less serious than rheumatic fever, even though it occurs more frequently.

Toxic shock syndrome

In rare cases, the toxin produced by group A Streptococcus bacteria can cause a condition known as toxic shock syndrome, or TSS. This state of 'shock' is characterized by a sudden fever and extreme drop in blood pressure (hypotension). These symptoms may occur together with dizziness, confusion, vomiting or diarrhea. If left untreated, the toxins may also damage the skin and organs. However, there is a good chance of recovery if the condition is diagnosed and treated early.

Prognosis

The outlook for scarlet fever is usually very good, particularly when the condition is correctly diagnosed and treated early with antibiotics. In most cases, the condition clears within about a week of starting treatment and complications are rare. Scarlet fever is usually contagious in the two days before symptoms appear, up until one or two days into treatment.

Even when left untreated, the fever usually ends quite suddenly after about five days. The rash generally fades and then begins to peel about a week later. However, it may take several more weeks for the throat to return to normal, during which time it is still possible to pass on the infection.

Prevention

Scarlet fever may be prevented by avoiding contact with people who have a sore throat or skin infection caused by group A Streptococcus bacteria. If contact cannot be avoided, the likelihood of developing scarlet fever may be reduced by maintaining good hygiene measures.

Teaching children good habits, such as washing hands and covering their mouths with a tissue or the inside of the elbow when coughing or sneezing, can also help to prevent the spread of infection. Keeping children with scarlet fever away from organized activities, such as childcare or school, is usually recommended until they are no longer contagious.

Replacing toothbrushes after starting antibiotic treatment can also reduce the possibility of reinfection of the throat. Similarly, taking the full course of antibiotics prescribed by your doctor may help to limit further spread of Streptococcus bacteria.