Scarlet Fever in Children: Symptoms, Causes, and How to Tell It From Other Rashes

Scarlet fever is an acute contagious illness caused by Group A Streptococcus bacteria (Streptococcus pyogenes), most often affecting children between about 5 and 15 years of age. It is characterized by a sore throat, high fever and a distinctive fine red rash. A person catches scarlet fever from someone who is already ill, either through direct close contact or through objects the sick person has touched or that were near them.

What scarlet fever is: definition and general overview

Scarlet fever, also called scarlatina, is a bacterial infection that develops in some people who have a Group A streptococcal throat or skin infection. The illness combines the features of strep throat with a widespread rash produced by toxins that the bacteria release. The rash gives the skin a flushed, sunburned, "scarlet" appearance — the feature that gave the disease its name. Although scarlet fever was once a leading cause of childhood death, effective antibiotics have made it a far less dangerous illness today, provided it is diagnosed and treated promptly.

Historically, scarlet fever was described by physicians as early as the 16th and 17th centuries — the Sicilian anatomist Giovanni Filippo Ingrassia distinguished it from measles, and later authors such as Jean Cottyar helped define it further. In the 1920s, George Dick and Gladys Dick identified the streptococcal toxin responsible for the rash, proving the bacterial cause. Case numbers and severity fell dramatically through the 20th century, but notable outbreaks have re-emerged since 2014 in England, Hong Kong and elsewhere, with a further surge across the United Kingdom and parts of Europe from September 2022 linked to more virulent strains.

What causes scarlet fever

Scarlet fever is caused by Group A beta-hemolytic streptococci (GABHS) — the same bacteria that cause strep throat and the skin infection impetigo. In a person infected with these bacteria, scarlet fever occurs when the particular streptococcal strain produces a streptococcal pyrogenic exotoxin (also called erythrogenic toxin). This toxin circulates through the body and triggers the characteristic rash, which is why not everyone with strep throat develops scarlet fever.

The microbes that cause scarlet fever live in the nose, nasopharynx, throat and mouth of the sick person. For this reason infection most easily passes through items contaminated with secretions from the nose and mouth — a handkerchief, towel, cutlery, cups and similar objects. Sometimes children fall ill with scarlet fever after contact with adults who have a sore throat (streptococcal tonsillitis), because the same bacteria are responsible.

The bacterial nature of the disease: Group A Streptococcus

Streptococcus pyogenes belongs to Group A of the Lancefield classification, a system that sorts streptococci by their surface carbohydrates. These bacteria carry a surface protein called M-protein, a key virulence factor that is used to serotype and genotype different strains and that helps the organism evade the immune system. The pyrogenic exotoxins (SPEs) act as superantigens — they provoke an exaggerated immune response, and through a process resembling molecular mimicry they can drive later autoimmune complications such as rheumatic fever.

How scarlet fever is transmitted

Scarlet fever spreads from an infected person mainly through respiratory droplets released when they cough, sneeze or talk, and through direct contact with contaminated objects. The bacteria concentrate in the nose and throat, so shared personal items — towels, handkerchiefs, cups, plates — are common vehicles. Crowded settings such as schools, nurseries and households greatly increase the chance of spread, and cases tend to rise in late winter and spring.

Routes of infection and the contagious period

An untreated person with scarlet fever can remain contagious for two to three weeks after symptoms begin. Once appropriate antibiotic treatment is started, contagiousness drops sharply, and most people are no longer infectious after about 24 hours of treatment. This is why children are usually advised to stay away from school or nursery, and adults away from work, until they have had at least 24 hours of antibiotics and feel well enough to return.

Who is most affected: age groups and risk factors

Children between about 5 and 15 years old carry the greatest risk of scarlet fever, and the disease is uncommon before the age of about 2 because of residual maternal immunity. Close, prolonged contact in crowded environments — the same classroom, day-care room or family home — is the strongest driver of transmission. Certain populations, including Aboriginal and Torres Strait Islander communities in Australia and Alaska Native and other Native American groups, experience a higher burden of Group A streptococcal disease and its complications.

Scarlet fever in pregnancy

Scarlet fever in pregnancy is generally not considered a direct threat to the developing baby, and the same Group A streptococcal bacteria are the cause. Pregnant women who develop a sore throat, fever and rash, or who have been in close contact with a confirmed case, should contact their doctor, since penicillin and amoxicillin — the usual first-line antibiotics — are considered safe to use during pregnancy. Group B streptococcus, which is screened for late in pregnancy, is a different organism and is unrelated to scarlet fever.

Course of the disease and the incubation period

The first signs of scarlet fever appear 3 to 4 days after infection, once the bacteria have entered the body — this is the so-called latent, or incubation, period. Sometimes it lasts only a day, but it can stretch to 10 to 12 days. After that the illness develops very quickly.

On the very first day the temperature rises to 38–40 °C, vomiting is not uncommon, and pain in the throat on swallowing appears.

Symptoms of scarlet fever

The typical symptoms of scarlet fever are a high fever, a painful red throat, a "strawberry" tongue, swollen neck lymph nodes and a fine red rash spreading over the body. The illness usually begins with flu-like symptoms before the rash emerges, and later the affected skin peels as recovery sets in.

Fever and the first signs

The earliest signs are a sudden fever, often reaching 38–40 °C, sometimes with vomiting and a headache, followed quickly by a sore throat that hurts on swallowing. This flu-like onset can precede the rash by a day or so, which is why the early stage is easily mistaken for an ordinary throat infection.

Changes in the throat, on the tongue and in the lymph nodes

In the mouth and throat there is a very bright redness of the mucous membrane of the soft palate and the tonsils. For the first 2 to 3 days the tongue is dry and heavily coated; as this coating clears it leaves the swollen red papillae standing out, producing the classic "strawberry tongue". The lymph nodes in the neck are enlarged and tender when touched.

The characteristic rash on the body

Toward the end of the first day or the beginning of the second day, the rash typical of scarlet fever appears, made up of tiny, very densely packed red dots. Between the dots the skin is slightly reddened, so the rash is not always easy to see at first glance. It has a fine, rough texture often compared to sandpaper.

To make it easier to detect, press on the skin with a finger and then lift it away: against the skin that has paled from the pressure, distinct red spots become clearly visible. The rash usually covers the whole body but shows up most vividly in the folds of the arms and legs — the groin, the back of the knee and the crease of the elbow. On darker skin tones the redness can be harder to see, so it is important to feel for the rough, sandpaper texture and to check the tongue and inside the mouth as well.

The rash lasts on average 3 to 5 days. As it fades, the skin of the fingertips, palms, soles and other areas begins to peel — a process called desquamation that can continue for several weeks and is a normal part of recovery.

Atypical forms and cases without a rash

It must be remembered that scarlet fever, though rarely, can run its course with only a faint rash or even without any rash at all. This is why it is always very important for parents to know when, and with which children, their child was in contact before falling ill. In young children the picture may be subtle — a facial flush without an obvious body rash, or little more than a fever and sore throat.

It happens, for instance, that a child suddenly develops a fever and a sore throat on swallowing, and it then turns out that the child had been together with other children, one of whom soon came down with scarlet fever. In such cases, even if there is no rash, precautions must be taken at once to prevent scarlet fever spreading to other children, and a doctor must be called immediately.

Complications of scarlet fever

Most children recover fully, but untreated or severe scarlet fever can lead to complications, which fall into two groups: suppurative (pus-forming) complications that appear early, and non-suppurative complications that develop later. Prompt antibiotic treatment greatly reduces the risk of both.

Suppurative complications

Suppurative complications arise when the streptococcal infection spreads directly from the throat to nearby or distant tissues. They include ear infections, sinusitis, abscesses around the tonsils, pneumonia and, rarely, meningitis. In severe invasive Group A streptococcal disease the bacteria can cause streptococcal toxic shock syndrome or necrotizing fasciitis, both medical emergencies.

Late complications and long-term consequences

Non-suppurative complications are immune-driven and appear weeks after the acute illness. Acute rheumatic fever, diagnosed using the Jones criteria, can damage the heart valves — especially the mitral valve — leading to rheumatic heart disease. Post-streptococcal glomerulonephritis affects the kidneys, and post-streptococcal reactive arthritis affects the joints. Some researchers also link Group A streptococcal infections to the neuropsychiatric condition known as PANDAS. Completing the full antibiotic course is the main way to prevent rheumatic fever.

Diagnosis of scarlet fever

Doctors diagnose scarlet fever from the combination of a sore throat, fever, strawberry tongue and the typical sandpaper rash, confirmed by testing for Group A streptococcus. A rapid antigen detection test (RADT) on a throat swab gives an answer within minutes; a throat culture, though slower, remains the reference standard, and molecular tests (NAAT) offer high accuracy. Because acute pharyngitis has many causes, this laboratory confirmation helps distinguish scarlet fever from viral sore throats, measles and other rashes in the differential diagnosis.

Treatment of scarlet fever

Scarlet fever is treated with antibiotics, which shorten the illness, reduce contagiousness and prevent complications such as rheumatic fever. A child with scarlet fever should, where necessary, be placed in medical care promptly, and it is essential to finish the entire course of medication even after the child feels better.

Antibiotic therapy and the effectiveness of penicillin

Penicillin remains the first-line treatment for scarlet fever because Group A streptococcus has never developed resistance to it. Oral penicillin V (Penicillin VK) or amoxicillin, taken for the full 10-day course, is the standard regimen recommended by bodies such as the American Academy of Pediatrics and the Infectious Diseases Society of America. Amoxicillin is often preferred for children because it tastes better and can be given once or twice daily.

Alternative antibiotics for penicillin allergy

For patients allergic to penicillin, alternative antibiotics are used. These include a cephalosporin such as cefalexin (for those without a severe penicillin allergy), or macrolides such as erythromycin, azithromycin and clarithromycin. Clindamycin is another option, though local antibiotic resistance patterns among Group A streptococci to macrolides should be considered when choosing an alternative.

Care of the patient and isolation

Once a child is diagnosed, supportive care eases the symptoms while the antibiotics work. Paracetamol helps lower fever and relieve throat pain, plenty of fluids and soft foods soothe swallowing, and calamine lotion or antihistamines can calm any itching. The sick child should be kept away from other children until at least 24 hours of antibiotic treatment have passed. After a patient who needed hospital care has been transferred, the room where they stayed and all the items they used are thoroughly disinfected.

Prognosis and recovery timeline

With antibiotic treatment the outlook for scarlet fever is excellent, and serious complications are now rare. Fever and sore throat usually improve within a few days of starting antibiotics, the rash fades over about a week, and the peeling of the skin can continue for several weeks before the skin returns to normal. Children who complete their treatment recover fully; only untreated cases carry a meaningful risk of the heart, kidney and joint sequelae, so long-term monitoring is reserved mainly for those who develop rheumatic fever.

Prevention of scarlet fever

There is no vaccine against scarlet fever, so prevention rests on limiting the spread of Group A streptococcus. Good hand hygiene, covering the mouth and nose when coughing or sneezing, and not sharing cups, cutlery, towels or handkerchiefs all reduce transmission. Keeping an ill child at home until 24 hours after antibiotics have begun, and seeking early treatment for anyone with a strep throat, further protects those around them. Public health surveillance helps track outbreaks and guide the response when case numbers rise.

Disinfection of the room and the patient's belongings

A child with scarlet fever should be placed in hospital as quickly as possible where the situation requires it. After the patient has been sent to hospital, thorough disinfection is carried out of the room where they stayed and of all the items they used. Washing bedding, towels and clothing at a high temperature, and cleaning frequently touched surfaces, removes bacteria left behind and helps prevent scarlet fever from passing to other children in the household.