Scarlet fever is an infectious disease caused by strains of beta-hemolytic streptococcus type A – Streptococcus pyogenes. It is the most common infectious disease affecting children of preschool and early school age. Adults also fall ill because having scarlet fever does not guarantee acquiring lasting immunity to it. Scarlet fever is also not observed in infants under 6 months of age, because they have specific antibodies passed on from their mothers, which protect them from infection.
Scarlet fever primarily spreads through respiratory droplets, but it can also be transmitted via contaminated objects, such as towels, bedding, or underwear that have been in contact with an infected person. The bacteria responsible for scarlet fever originate from either an infected individual or an asymptomatic carrier. Large population centers are significant risk factors for the spread of scarlet fever and other droplet-transmitted illnesses.
Moreover, only specific strains of bacteria that produce erythrogenic toxins can cause scarlet fever. These toxins are responsible for the characteristic rash seen in affected individuals.
The incubation period of scarlet fever is from 2 to 5 days. During this time, no alarming symptoms are usually observed.
In most cases, scarlet fever is diagnosed based on characteristic symptoms. However, there are cases with few symptoms, which can be difficult to diagnose. The symptoms may resemble an allergic reaction, especially when the rash is abundant and itchy. Therefore, after conducting an interview and examining the patient, the doctor may decide to perform additional tests to confirm scarlet fever. One of the tests is a throat culture for Streptococcus pyogenes type A. The presence of this bacteria in a throat swab indicates scarlet fever. General laboratory tests performed on a venous blood sample show an increase in the number of eosinophils, ASO level, and ESR.
After this time, patients complain of:
A very characteristic symptom of scarlet fever is a rash that appears on the trunk and limbs on the second or third day of the illness. Moreover, the lesions resemble pinpricks or marks from a rice brush and can be on the abdomen, armpits, groin, and buttocks.
About a week after the rash disappears, the skin begins to peel. This peeling can persist for several weeks. In cases where a rash was absent, this characteristic skin peeling can allow for a retrospective diagnosis of scarlet fever.
Additionally, a feature known as the Filatov triangle—a pale area around the nose and mouth—is often seen in scarlet fever cases.
Other indicators of scarlet fever include the appearance of the throat, tongue, and tonsils. The mucous membrane in the throat takes on an intense red, scarlet color (which is how the disease gets its name). The tonsils become swollen, and the tongue may be covered with a white coating. This coating gradually disappears, leaving the tongue with a light red color.
From the onset of the disease, the mucous membranes of the throat, tonsils, palate, and uvula often appear red—sometimes even bright red—and swollen. A rash may also develop on the palate and uvula.
During the course of scarlet fever, an exudate can form on the tonsils, which may be mucous, purulent, or fibrinous. This exudate can be localized to specific areas or cover the entire tonsil surface.
Moreover, the lymph nodes are painful, cohesive, can be moved, are single, do not form packets, there is no swelling of the peri-nodal tissue, and the skin over them remains unchanged, and they do not tend to soften. It is worth remembering that tonsillitis occurring in the course of scarlet fever in a child may have varying degrees of intensity.
The rash associated with this conition typically appears a few hours after the initial symptoms in a child, and it is present within 24 hours at the latest. It is characterized by a finely spotted, confluent pattern with a bright red, erythematous base. Notably, this rash does not cause itching. The skin's texture may be described as feeling “pricked with a rice brush” or similar to sandpaper, which conveys the appearance of the scarlet fever rash, even if these comparisons are not entirely precise.
The rash can affect the entire body except for the area known as the nasal-mental triangle (also referred to as the Filatov triangle). However, it is especially prominent in areas of increased warmth and the natural bends of the body. Additionally, a vascular indication of heightened fragility in small blood vessels (Pastia's sign) can also be observed in these areas.
The severity of the rash can vary; it may be only subtly visible or manifest with significant swelling of the subcutaneous tissue and numerous petechiae. Generally, the rash tends to resolve along with the other symptoms of the illness, typically after about seven days.
Scarlet fever is an infectious bacterial disease typical of childhood. However, it can also happen that adults fall ill – in such cases, this condition usually has a severe course. The cause of scarlet fever is an infection with beta-hemolytic streptococci type A (mainly Streptococcus pyogenes). These are the same pathogens that cause acute inflammation of the palatine tonsils or sore throat. Both infectious diseases can occur immediately after each other because scarlet fever is often a consequence of a sore throat. However, this is not a rule – everything depends on the individual immunity of the patient.
Children who spend time in large groups – kindergartens and schools – are particularly susceptible to scarlet fever. Most cases are recorded in the age group of 5-15 years. The source of infection is a sick person or a carrier of streptococcus – also adults. Infection occurs through droplets, but it also happens through infected objects that a child touches and then transfers on dirty hands to the oral cavity. A sick person is most contagious between the 3rd and 21st day of illness.
The incubation period of this condition is asymptomatic and short. It lasts from 1 to 7 days (usually 2-5 days). After this time, symptoms of the disease appear. Immediately after their appearance, it is worth consulting a pediatrician or internist (in the case of suspected infection in an adult). Complications of scarlet fever are dangerous, so it should be treated under the care of a specialist.
Scarlet fever occurs less frequently in adults compared to children. Initially, the symptoms in adults resemble those of the flu or other infections. The rash typically appears at least 24 hours after the first signs of the illness. In adults, the skin lesions are larger and may be mistaken for allergies. A distinctive symptom, however, is the redness on the face. Like children, adults with scarlet fever should remain at home, as untreated condition can lead to serious complications.
Remember that there are diseases that cause similar symptoms to scarlet fever. These include:
Scarlet fever should therefore be differentiated from them.
Measles is a highly contagious viral infection that is characterized by a thickly spotted rash, inflammation of the mucous membranes in the respiratory tract and conjunctiva, along with a fever.
The incubation period, i.e., until the appearance of prodromal symptoms, is on average 10 (8–12) days, and the period until the appearance of the rash is on average 14 (7–18) days. The risk of illness after contact in a person susceptible to infection is very high. The sick person infects other people from the moment of the appearance of prodromal symptoms to 3–4 days after the appearance of the rash. The virus remains infectious in the air or on contaminated surfaces for up to 2 hours.
The clinical course of measles is divided into the catarrhal period, the rash period, and the convalescent period. The catarrhal period lasts 3–4 days and includes:
After 3–4 days of the catarrhal period, white spots surrounded by a red border (Koplik spots) appear on the buccal mucosa. The spots disappear after the rash appears.
Rubella is a viral infectious disease and the only known reservoir for the virus in humans. The virus can be transmitted from one person to another through direct contact (via the droplet route), contact with infectious materials, or through the bloodstream from the mother to the fetus via the placenta in cases of congenital rubella. Infectious materials include the patient’s nasopharyngeal secretions, blood, feces, and urine.
In about half of cases, the infection is asymptomatic. Initially, rubella may manifest in worsening well-being, headaches and muscle pain, inflammation of the throat and conjunctiva (without photophobia), and low-grade fever. A day before the rash appears, there is a painful enlargement of the lymph nodes.
The rash itself is pink and resembles a scarlet fever rash. On the face, it resembles a measles rash. After 2 to 3 days, the rash usually resolves on its own, without leaving any discoloration, although there may be some skin peeling. In some individuals, the infection may be asymptomatic, with the only visible sign being persistent swelling of the lymph nodes. In young children, the rash may be the first noticeable symptom of the disease.
Diagnostics of scarlet fever should be performed by a doctor. Usually, a thorough medical interview and physical examination are enough to diagnose the disease (the symptoms are very characteristic). However, if there are doubts or for a more accurate assessment of the patient's general condition, the doctor may order additional tests:
Scarlet fever can sometimes be mistaken for rubella or measles; however, in vaccinated children, the likelihood of an incorrect diagnosis is minimal. The symptoms of scarlet fever also resemble those of Kawasaki disease. More severe cases of scarlet fever require careful differentiation from toxic shock syndrome and infections caused by other bacteria.
Scarlet fever treatment comes down to administering antibiotics from the penicillin group that acts on streptococci. Additionally, the patient is advised to take antipyretics and painkillers. The course of scarlet fever should be monitored by a doctor to avoid complications.
Scarlet fever, especially at the beginning of the disease, manifests itself with a severe sore throat that makes it almost impossible to eat. It is significant to ensure that the patient is given plenty of fluids to prevent dehydration. A saltwater gargle can be used to reduce throat swelling. Home remedies are not recommended for scarlet fever, as they are not very effective. However, they increase the risk of serious complications. Moreover, home remedies can only be used as a supplement to the treatment recommended by a doctor.
Having scarlet fever does not guarantee that you will not get it again. There is no vaccine for scarlet fever yet, so prevention is hard. Scarlet fever can only be prevented by following basic hygiene rules, such as:
Numerous epidemiological data show that scarlet fever can occur several times in a lifetime. Different strains of streptococcus causing scarlet fever produce different erythrogenic toxins (at least three types are known). The disease is the reaction to contact with a toxin produced by the infecting streptococcus. During the disease, antibodies are created that neutralize only this toxin, thus protecting the convalescent from re-infection with a strain of bacteria that produces this type of toxin.
Scarlet fever usually does not cause serious complications, although, in a more severe course of the disease, inflammation of the middle ear, heart muscle, liver, or joints is sometimes observed. In most cases, the symptoms gradually subside within a few days, and the peeling of the epidermis lasts the longest. Complications of scarlet fever after improper treatment (or lack thereof), such as rheumatic fever, are rare.
A reaction to viral or bacterial infections may also be glomerulonephritis, which is the result of the body's fight against streptococci (in the case of scarlet fever) or, for example, pneumococci or staphylococci (in the case of other infections). This disease is most often asymptomatic and resolves spontaneously.
Interestingly, you can get scarlet fever several times, but no more than three, because there are three types of bacterial toxins.
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