What is Scarlet Fever?
Scarlet fever is a type of rash that usually appears in kids at school age and adolescents as a result of a throat infection, often known as “bacterial pharyngitis” (you can see an image of Scarlet Fever too). The rash may feel like sandpaper to the touch and turns pale when you press on it. This rash is caused by a type of bacteria known as Streptococcus pyogenes, which releases a toxin, or poison, that primarily causes the rash.
These bacteria are further categorized as group A, which is why you might hear it called group A strep or GAS. While the rash itself isn’t harmful, it signals a GAS infection, which can lead to other complications, some of which involved pus formation and others that do not. That’s why it’s important to treat the infection quickly to avoid these problems. The most common treatment is a medicine called penicillin.
For those allergic to penicillin, a medicine from the first-generation cephalosporin class can be used. The infection spreads when bacteria from the infected person’s mouth or nose are transferred to others, most commonly in close quarter settings such as classrooms or workplaces.
What Causes Scarlet Fever?
Scarlet fever is caused by a bacteria known as GAS, which is a type of round-shaped germ that tends to grow in chains. This is a kind of bacteria that can completely destroy red blood cells, and because of this, it’s also known as beta-hemolytic strep.
The disease happens when these bacteria release harmful substances called endotoxins. Besides scarlet fever, this same bacteria can also cause other diseases such as strep throat, impetigo (a skin infection), erysipelas (a skin infection), cellulitis (a skin and underlying tissue infection), and necrotizing fasciitis (a severe infection also know as flesh-eating disease).
Risk Factors and Frequency for Scarlet Fever
Scarlet fever is a disease that often affects children due to its ease of spreading in classrooms and nurseries. It’s mostly related to bacterial throat infections caused by GAS (or strep throat) but can also result from wounds and burns infected with GAS. Strep throat is behind 15% to 30% of all throat infections in children aged 5 to 15 years, and 5% to 15% in adults. Also, children who are not in school but live with school-aged children are at risk for scarlet fever. It’s important to note that both boys and girls can get scarlet fever.
Interestingly, the onset of scarlet fever seems to coincide with the start of the school year and the drop in temperature during winter. There’s usually a reduction in the number of cases during school breaks and warmer weather in spring. The difference in the rates between children and adults likely comes from the fact that adults tend to have immunity that children don’t have yet. Poorer countries tend to have higher rates of scarlet fever, likely due to overcrowded living conditions.
- An article about scarlet fever in Hong Kong reported an increase in cases from 3.3 per 10,000 people to 18.1 per 10,000 people.
- Similar increases in scarlet fever cases have also been spotted in Great Britain.
- These increases haven’t been fully explained, but resistant strains of GAS are suspected to be the culprit.
Signs and Symptoms of Scarlet Fever
Scarlet fever is usually linked to an acute sore throat. This means that common symptoms include fever, throat pain, difficulty swallowing, and swollen neck glands. Sometimes, if there’s no throat infection, the cause may be a wound or burn that’s infected with a specific kind of bacteria. Both these sources can lead to scarlet fever.
The rash that appears with scarlet fever is different from allergy rashes. It’s made up of tiny, blanching bumps that emerge slowly and don’t merge together. This results in a rough ‘sandpaper’ feel. You won’t see any little fluid-filled sacs or pus-filled bumps, as these are signs of other conditions like chickenpox or skin infections.
The rash usually shows up 2 to 3 days after the infection starts, but it can take up to 7 days. It begins on the trunk, underarms, and groin, then spreads to the arms and legs. The palms, soles and area around the mouth are usually not affected. An associated symptom is a ‘strawberry tongue’. This starts with a white coating on the tongue with enlarged bumps (papillae). The white layer then disappears, leaving the red, bumpy papillae, which look like a strawberry. Skin folds, like the neck, elbow crease, and groin, can show lines of tightly packed bumps around pressure points.
Once the initial rash starts to improve, the affected skin can peel, sometimes for up to two weeks.
Testing for Scarlet Fever
If a doctor thinks you might have scarlet fever, they will do a few things to be sure. They will ask you questions about your symptoms and do a physical check-up. Then, they could do a couple of tests if they think your symptoms look a lot like strep throat, which usually comes with scarlet fever.
Strep throat signs are no cough, a sore throat with pus, swollen neck glands, a fever, and being younger than 15. These are all known as CENTOR criteria. The doctor can do a throat culture or a rapid strep test to find out if Group A Streptococcus (GAS), the bacterium that usually causes this illness, is present.
The throat culture is more accurate but takes days to give a result. On the contrary, the rapid strep test takes only minutes. With older adults, doctors must decide if a rapid strep test is necessary because they can carry GAS in their throats without getting sick and are less likely to get the disease. However, needless use of this test could lead to too many antibiotic treatments, making the bacteria more drug-resistant.
Therefore, if a young patient’s symptoms match well with the CENTOR criteria, a rapid strep test is recommended to confirm if it is indeed scarlet fever, and then treatment is started. The choice to treat can also depend on where your doctor’s office is and whether or not you can visit again soon.
Treatment Options for Scarlet Fever
Scarlet fever is caused by an infection known as ‘group A streptococcus’, or GAS for short. The condition is typically treated with antibiotics. Penicillin or amoxicillin are generally the first choices. If someone is allergic to penicillin, they may be given alternatives like a specific type of cephalosporin, clindamycin, or erythromycin.
By using antibiotics, we’ve managed to greatly reduce the risk and serious consequences of scarlet fever compared to a century ago. Back then, it was a dangerous disease that led to death in about 30% of patients.
GAS bacteria are mostly found in the nose, adenoids, and tonsils. There are people who carry and can spread these bacteria without showing any symptoms themselves. Although they test positive for GAS, they’re known as ‘carriers’. The current standard of care doesn’t usually involve treating these carriers with antibiotics.
What else can Scarlet Fever be?
When a patient has a fever and rash together, there could be many possible causes. If the rash feels like sandpaper and the patient also has a sore throat, it might indicate a type of infection known as GAS. Doctors use something called the CENTOR criteria along with various tests to make this diagnosis. Sometimes, it’s a local infection like impetigo or erysipelas that’s causing the symptoms. This is usually signaled by pustules, or small bumps filled with pus on the skin.
To look into other causes, doctors consider viral illnesses such as measles, chickenpox, and hand-foot-and-mouth disease, which are common in the affected groups and can be distinguished from scarlet fever due to their specific symptoms:
- Measles, also known as rubeola
- Chickenpox, also known via the medical term herpes zoster
- Hand-foot-and-mouth disease, caused by the coxsackie virus
Lastly, the doctor would look at the immunization, travel, and medical history of the individual to determine the cause of the fever and rash.
What to expect with Scarlet Fever
Compared to the early 1900s, the outlook for patients with scarlet fever today is much better. This improvement is largely thanks to the development of antibiotics and better hygiene practices. Once a doctor diagnoses scarlet fever and starts treatment, the patient can generally go back to their regular activities 24 hours after the fever is gone.
However, if scarlet fever isn’t treated in time, the situation can get worse and can lead to serious complications linked to a type of bacterial infection known as Group A Strep. These complications could range from painful pus-filled pockets of infection (abscess) near the original infection site to damage to the kidneys.
Possible Complications When Diagnosed with Scarlet Fever
In the past, scarlet fever used to be a dangerous disease for children, often leading to serious complications and even death. Nowadays, thanks to antibiotics and improved treatments, scarlet fever has become a relatively mild disease. However, if Group A Streptococcus (GAS) infection associated with it doesn’t get treated on time, it can lead to significant complications. These complications can be of two types: suppurative and non-suppurative.
Suppurative complications happen when the original infection worsens, spreads, or extends to other parts of the body. For example, a bacterial throat infection can spread to the ear causing otitis media, or to the sinuses causing sinusitis, and even to the protective layers around the brain causing bacterial meningitis.
Meanwhile, non-suppurative complications typically occur after the original infection has resolved, and are caused by an immune response. Rheumatic fever is one of these complications, it affects the heart valves and is a long-term side effect of the GAS infection.
Note that scarlet fever does not directly cause the following complications, but they can result from GAS infection:
Suppurative Complications:
- Peritonsillar/pharyngeal abscess
- Otitis media
- Sinusitis
- Necrotizing fasciitis
- Streptococcal bacteremia
- Meningitis or brain abscess
- Jugular vein septic thrombophlebitis
Non-Suppurative Complications:
- Acute rheumatic fever
- Poststreptococcal reactive arthritis
- Streptococcal toxic shock syndrome
- Acute glomerulonephritis
- Pediatric autoimmune neuropsychiatric disorder associated with group A
streptococci
Preventing Scarlet Fever
Diseases like scarlet fever, which spread through close contact, can often be prevented by maintaining good hygiene. This includes washing your hands regularly, covering your mouth when you cough or sneeze, cleaning shared items frequently, and staying away from others if you’re sick. Posters in public areas and announcements on TV or radio are some ways we can encourage everyone to practice good hygiene.
It’s also essential for everyone to understand the risks of using antibiotics too much. Overuse can lead to a situation where certain strains of bacteria, like Group A Streptococcus (GAS), become resistant to these drugs. This means that the antibiotics will stop working against these strains, making infections harder to treat.
