Introduction:

It is an infectious disease which most commonly affects children. Symptoms include sore throat, fever and a characteristic red rash. Scarlet fever is usually spread by inhalation. There is no vaccine, but the disease is effectively treated with antibiotics. Most of the clinical features are caused by erythrogenic toxin, a substance produced by the bacterium Streptococcus pyogenes (group A streptococcus) when it is infected by a certain bacteriophage.Before the availability of antibiotics, scarlet fever was a major cause of death. It also sometimes caused late complications, such as glomerulonephritis and endocarditis leading to heart valve disease, all of which were protracted and often fatal afflictions at the time.

Pathophisiology:

The primary site of infectio  in scarlet fever is usually pharynx or tonsils but the diseasecan be associated with streptococcal infection in other sites,e.g.in the genital tract after childbirth or in wounds. It is airborn infection .Scarlet fever is usually spread by the aerosol route (inhalation) but may also be spread by skin contact or by fomites. Although it is not normally considered a food-borne illness, or more rarely by milk or ice-cream contaminated by streptococci, an outbreak of scarlet fever due to infected chicken meat has been reported in China.Asymptomatic carriage may occur in 15–20% of school-age children.

Incubation Period:

 Incubation Period is 2-4 days.

Clinical Features :

Scarlet fever occurs most commonly in children.It has a sudden onset and the more severe cases present with a sore throat, shivering,pyrexia,Headach and vomiting.There is inflammation of the fauces;the tonsils are enlarged and may be covered with a follicular exudates.there is a tender enlargement of the tonsillar lymph nodes.The rash,which usually first appears behind the ears on second day,rapidly becomes generalized punctuate erythema.It  is most intense in the flexures of arms and legs.

The face is not affected by rash, but it is flushed due to fever and region around the mouth is pale as shown in Fig. below.

The tongue is initially furred but shows prominent red palillae.

The rash fades in about 1 week and is succeeded by desquamation.A profound growth of strep pyogenes can usually be obtained from a throat swab.

Complications :

The complications are less common. Otitis Media,cervical adenitis and sinusitis may occure.Rheumatic fever and glomerulonephritis are rare sequelae which develop 2 or 3 weeks after the onset of any haemolytic streptococcal infection.

Treatment:

The treatment for Scarlet fever is the same as for streptococcal sore throat.Most patients respond  rapidly to Phenoxymethylpenicillin(250 mg for children) and ( 500 mg for adults) 6- hourly for 7 days.