Scarlet fever (synonyms: scarlatina (scarlet fever); scarlet fever; scarlet angina; streptococcal angina; ICD-10 A38: scarlet fever) is an infectious disease of the throat caused by the bacterium Streptococcus pyogenes (serogroup A; group A β-hemolytic streptococci; GAS (group A streptococci)).
In addition to this infectious disease, the bacterium also causes diseases such as erysipelas (erysipelas) or necrotizing fasciitis (foudroyant life-threatening infection of the skin, subcutis (subcutaneous tissue) and fascia with progressive gangrene; often patients with diabetes mellitus or other diseases leading to circulatory disorders or reduced immune defenses).
Scarlet fever is a special form of pharyngitis (inflammation of the throat) in which toxins are produced by the bacterium, which in turn lead to a systemic (affecting the entire organism) infection.
A new strain of Streptococcus pyogenes has been discovered in England and Wales that produces significantly more exotoxin A and is thought to be responsible for the increase in invasive scarlet fever in this region.
The pathogen reservoir is humans.
Occurrence: The infection occurs worldwide.
In order to quantify the contagiousness (infectiousness or transmissibility of the pathogen) mathematically, the so-called contagiousness index (synonyms: contagion index; infection index) was introduced. It indicates the probability of a non-immune person becoming infected after contact with a pathogen.The contagiousness index for scarlet fever is 0.1-0.3, which means that 10-30 out of 100 unvaccinated persons become infected after contact with a scarlet fever infected person.Manifestation index: Approximately 30-40% of scarlet fever infected persons become recognizably ill with scarlet fever.
Seasonal accumulation of the disease: Scarlet fever occurs more frequently from October to March.
Transmission of the pathogen (route of infection) is mostly aerogenic (droplet infection in the air; through sneezing and coughing), in rare cases also through contaminated food or water.
Human-to-human transmission: Yes.
Incubation period (time from infection to onset of disease) is usually 2-4 days.
Peak incidence: The disease occurs predominantly between the ages of 3 and 10 years.
The number of pharyngitis caused by streptococci is estimated at 1-1.5 million per year (in Germany).
Infectivity (contagiousness) usually ends 24 hours after starting antibiotic therapy. During the first days of therapy, infected persons should avoid community facilities such as kindergartens or schools.
The disease leaves lifelong immunity to the respective disease-causing group A streptococcus type (= A streptococcus). However, since there are many different types, the disease can occur several times.
Course and prognosis: The disease is easily treatable with antibiotics. If therapy is not adequate, complications such as rheumatic fever (about 3 weeks after A-streptococcal pharyngitis), glomerulonephritis (kidney disease, with inflammation of the kidney filters; 1-5 weeks after A-streptococcal pharyngitis) or myocarditis (inflammation of the heart muscle) may occur. Hematogenously (via the bloodstream), the infection can spread throughout the body (septic course), although this is very rare.
In some parts of Germany, the disease is notifiable according to the Infection Protection Act (IfSG).
