Scarlet fever (Scarlatina) is an acute infectious disease caused by β-hemolytic streptococci. It predominantly occurs in children aged 3 to 10 years, though it can also occur in older children and adults. Transmission occurs usually by droplet infection via the respiratory tract.
This disease presents with a sore throat after which fever sets in. There is redness and swelling of the tongue with spots called ‘Strawberry tongue’. Small red spots may also be present inside the oral cavity, particularly on the soft palate called Forchheimer spots.
Scarlet fever is classically manifested by a punctuate erythematous rash that is most prominent over the trunk and inner aspects of the arms and legs . The rash is a characteristic feature of scarlet fever. It presents within 12-72 hours after the fever sets in and appears as a fine, rough, red coloured rash that begins in the trunk and armpits and then progresses over to the face and the rest of the body. It typically blanches under pressure and when present on the face, it presents with erythema of the face leaving a pale circular area around the mouth, which is called circumoral pallor. This rash is characteristically prominent on skin folds, called Pastia lines.
Imaging studies are not required to diagnose scarlet fever.
On the basis of results of throat culture and antibody testing, a diagnosis can be made.
Most scientists recommend penicillins, like benzylpenicillin and phenoxymethylpenicllin as drugs of first choice for effective treatment of Streptococcus tonsillopharyngitis and scarlet fever . Erythromycin may be considered as an alternative drug if patients are resistant or allergic to penicillin or 1st generation cephalosporins . A 10 day course of the antibiotics is generally sufficient to treat the infection. Patients should also be kept isolated during the course of the disease to prevent transmission.
Scarlet fever is considered an infectious, toxin-mediated disease whose pathogenicity depends upon production of specific exotoxins .
The main causative agent of scarlet fever is a gram positive bacterium called Streptococcus pyogenes, which belongs to the β-hemolytic group A streptococci, and is a natural colonizer of the human nasopharynx and oral cavity. S. pyogenes causes the widest range of infectious diseases in humans among all known bacterial pathogens . Other members of the group A streptococci are also implicated in causing scarlet fever.
There has been a confirmed outbreak of person-to-person transmitted scarlet fever, and the main risk factor was having a relative with tonsillitis . Transmission is mainly air borne; via inhaled aerosol droplets containing the infectious agents, but the illness can be also be food borne.
Increases in scarlet fever above usual seasonal levels are currently being seen across the United Kingdom . Worldwide, around 10% of people are likely to get a throat infection from group A streptococci, and only 10% of these people are likely to develop scarlet fever.
Scarlet fever is a rare disease in adult patients . It typically affects young children between 5-15 years. Usually as the child reaches 10 years of age and above, antibodies to GAS strains are developed and circulated in the body, making the child fairly immune to further infections by the same bacteria.
This disease affects males and females equally.
The infective organisms may be inhaled or ingested, and after infection by a strain of group A streptococci, an incubation period of 1 to 4 days takes place. The bacteria produce pyrogenic toxins that cause the characteristic rash and fever. According to a retrospective study conducted in Taiwan, the frequencies of pyrogenic exotoxin genes were 9.5% for speA, 81.0% for speB, 4.8% for speC, and 71.4% for speF in isolates from patients of scarlet fever . Inflammatory process begins which contributes to the redness of the rash. Patients are infective both during this as well as the subclinical period.
Scarlet fever has no vaccine available. Because of the wide distribution of S. pyogenes in the general population and the lack of an effective vaccine, possibilities for prevention allowing a suitable protection for diseases due to S. pyogenes are very limited .
Scarlet fever is one of a variety of diseases caused by group A streptococcus (GAS) . It may be endemic, epidemic or sporadic and indeed many outbursts throughout the world have been reported in the past years. Scarlet fever is usually associated with pharyngitis which is the primary mode of illness by species of the group A streptococci, and often occurs after a throat infection. Although it is now perfectly treatable with the help of antibiotics that target gram positive bacteria, scarlet fever was a source of high mortality in the past.
It is caused by bacteria belonging to group A Streptococci, which are gram positive strains and many are normally present in the nasopharynx.
Signs and symptoms
Scarlet fever begins with a sore throat which then progresses to a fever and a characteristic rash all over the body. The tongue becomes bright red and is called strawberry tongue. The infection persists for 3-6 days and the rash begins to peel off after 5-6 days.
Diagnosis can be made clinically if characteristic signs are present. Throat culture is considered gold standard for diagnosis and antibody testing can also aid the diagnosis.
Treatment is a course of antibiotics for 8-10 days along with bed rest and avoidance of public places to reduce the chances of transmission.