- Incubation Period
- Risk Factors
Facts you should know about scarlet fever
- Scarlet fever is a bacterial infection caused by group A Streptococcus bacteria that results in a rash and fever.
- Group a beta hemolytic streptococci produce an erythrogenic toxin that causes scarlet fever.
- The incubation period for scarlet fever is about 12 hours to seven days.
- Risk factors for scarlet fever include overcrowding, especially with children age 5 to 15 years old and the communal use of utensils, towels, or other substances.
- The contagious period for scarlet fever ranges from about 12 hours after exposure to the bacteria, even if the individual shows no symptoms, and during the acute phase when the person has a rash and fever; it ends after the fever has gone away for at least 12 hours.
- The signs and symptoms of scarlet fever include fever of 101 F or higher, a sandpaper-like rash, strawberry-like tongue texture, and other features that are relatively nonspecific such as nausea and vomiting, headache, swollen glands, and body aches.
- The diagnosis of scarlet fever is usually preliminarily made by the patient's history and physical exam, especially if the person has the typical rash and fever; however, isolation of streptococci from the patient usually provides the definitive diagnosis.
- The treatment for scarlet fever is antibiotics that are effective against the infecting streptococci.
- Complications of scarlet fever can include rheumatic fever and kidney problems; other serious problems can occur rarely, including death.
- The prognosis of scarlet fever, if treated early and effectively, is very good; such treatment usually prevents complications. However, if complications develop, the prognosis decreases depending upon the involvement of other organ systems.
- It's possible to reduce or prevent the chance of getting scarlet fever by good hand-washing techniques and by not using others utensils, towels, or other personal grooming products. There is no vaccine for humans against scarlet fever.
What is scarlet fever?
Scarlet fever is a bacterial infection caused by group A Streptococcus bacteria. This illness usually occurs in a few people (about 10%) who have strep throat (streptococcal pharyngitis) and occasionally streptococcal skin infections or even wound infections. Scarlet fever is also known as scarlatina in the older articles; group A Streptococcus (for example, Streptococcus pyogenes) is often shortened to read as "group A strep" or group A beta-hemolytic streptococci (GABHS). Scarlet fever is mainly known for its sunburned-skin-colored sandpaper-like skin rash that is associated with fever.
Outbreaks occur. England reported a 50-year high number of individuals diagnosed with the disease (over 19,206) in 2016.
What causes scarlet fever?
Group A beta hemolytic streptococci (GABHS) bacteria are the cause of scarlet fever. These gram-positive coccus-shaped (elliptically shaped) organisms, while infecting a body site, can produce an erythrogenic (producing a red colored) toxin. This toxin is responsible for causing the sandpaper-like red-colored skin rash. Researchers have shown that about 80% of children who reach age 10 have developed lifelong protective antibodies against the Streptococcus exotoxin. These bacteria can cause other symptoms and/or diseases such as impetigo, skin desquamation, myositis, acute rheumatic fever and necrotizing fasciitis.
What is the incubation period for scarlet fever?
The incubation period for scarlet fever has a fairly wide range from about 12 hours to seven days. Individuals are contagious during this first subclinical or incubation period and during the acute illness. The primary strep infection is the contagious aspect. The rash itself is not contagious.
What are risk factors for scarlet fever?
Risk factors for scarlet fever are overcrowded conditions (schools, dormitories, institutional settings). Children 5-15 years of age are the population that is usually seen with scarlet fever, although it can occur in some older children and adults. Scarlet fever is rare in children younger than 2 years old because of maternal antibodies.
What is the contagious period for scarlet fever?
As stated previously, the contagious period for scarlet fever occurs during both the initial subclinical (before development of symptoms) phase, about 12 hours to seven days after initial contact with the bacteria, and during the acute phase when the person has the rash and fever.
What are scarlet fever symptoms and signs?
Scarlet fever symptoms and signs may include a reddish sore throat, a fever (101 F or above), and a widespread red rash (exanthem) with a sandpaper-like texture, and a tongue that resembles a strawberry (red with small bumps also termed strawberry tongue). Some patients will have whitish coating on the tongue or the throat and may have swollen lymph nodes glands, headache, abdominal pain or discomfort resulting in nausea and vomiting, and/or body aches. The classic description of the rash of scarlet fever has been described as "goose bumps (papule) on a sunburned skin" or "boiled-lobster" skin.
How do physicians diagnose scarlet fever?
In most cases, the patient's history and physical exam will result in a presumptive diagnosis of scarlet fever. For example, the physical exam may reveal Pastia's signs or Thompson's signs where pink or red lines form in skin creases of the armpits and groin. The lines may form before the rash develops and may remain as pigmented lines after desquamation (skin peeling off). However, a health care professional may obtain a throat culture or swab (or rarely, swabs from a wound or other sites of infection) to determine if GABHS are present. Unfortunately, there are many other infections, like measles, that can cause both a skin rash and a fever. Isolation of GABHS usually is enough to confirm the diagnosis of scarlet fever. An infectious disease specialist may be consulted if complications develop. If GABHS is not identified, the symptoms and signs are likely due to another underlying problem.
What is the treatment for scarlet fever?
The treatment for scarlet fever is antibiotics that are effective against GABHS. Usually about 10 days of an oral penicillin medication (for example, amoxicillin) is effective early treatment. Rarely, some patients may need to be treated with a single injection of penicillin G benzathine (Bicillin L-A). This is most commonly indicated for a patient who is unable to retain oral antibiotics. Other effective antibiotics are members of the cephalosporin family (for example, cephalexin [Keflex]). A recent outbreak in China showed GABHS resistance to the common antibiotics used to treat scarlet fever. Antibiotics may prevent complications of scarlet fever such as rheumatic fever.
What are complications of scarlet fever?
Complications from scarlet fever may include kidney disease (termed post-streptococcal glomerulonephritis) and rheumatic fever (an inflammatory disease caused by antibody cross-reactivity that the effects the heart, joints, skin, and brain). Rheumatic complications can begin about two to three weeks after the initial infection; children between the ages of 6 and 15 are most susceptible to rheumatic fever development. Glomerular complications may begin about one to two weeks after throat infection or about three to six weeks after skin infection and usually cause more problems in adults than children.
What is the prognosis of scarlet fever? What are the long-term effects of scarlet fever?
The prognosis for scarlet fever, when treated appropriately with antibiotics, is usually excellent. Patients recover completely and the skin symptoms progressively decrease over several weeks. Untreated scarlet fever has a worse prognosis and before the use of antibiotics, scarlet fever had a mortality (death) rate of about 15%-20%. Currently, the mortality rate is less than 1% because of early recognition and early treatment with antibiotics. In general, appropriately diagnosed and treated scarlet fever results in few if any long-term effects. However, if complications develop for whatever reason, problems that include kidney damage, hepatitis, vasculitis, septicemia, congestive heart failure, and even death may occur.
Is it possible to prevent scarlet fever? Is there a scarlet fever vaccine?
The best way to prevent or lessen the chance of getting scarlet fever is hand washing. In addition, avoiding communal use of utensils, towels, or other personal items should be avoided. Transmission of the disease is person to person, usually by droplets, so direct contact with infected individuals should be avoided. Patients who are treated with antibiotics and have had no fever for about 24 hours are considered to be noncontagious. No vaccine is available for humans to prevent scarlet fever.