Course
Following exposure to streptococcus, onset of symptoms occur 12 hours to 7 days later. These may include fever, fatigue, and sore throat. The characteristic scarlatiniform rash appears 12–48 hours later. During the first few days of the rash development and rapid generalization, the Pastias Lines and strawberry tongue are also present. The rash starts fading within 3–4 days, followed by the desquamation of the rash, which lasts several weeks to a month. If the case of scarlet fever is uncomplicated, recovery from the fever and clinical symptoms, other than the process of desquamation, occurs in 5–10 days. Complications
The complications, which can arise from scarlet fever when left untreated or inadequately treated, can be divided into two categories: suppurative and nonsuppurative.Suppurative complications: These are rare complications that arise either from direct spread to structures that are close to the primary site of infection, or spread through the lymphatic system or blood. In the first case, scarlet fever may spread to the pharynx. Possible problems from this method of spread include peritonsillar or retropharyngeal abscesses, cellulitis, mastoiditis or sinusitis.In the second case, the streptococcal infection may spread through the lymphatic system or the blood to areas of the body further away from the pharynx. A few examples of the many complications that can arise from those methods of spread include endocarditis, pneumonia, or meningitis.Nonsuppurative complications: These complications arise from certain subtypes of group A streptococci that cause an autoimmune response in the body through what has been termed molecular mimicry.
In these cases, the antibodies which the persons immune system developed to attack the group A streptococci are also able to attack the persons own tissues. The following complications result, depending on which tissues in the persons body are targeted by those antibodies. Acute rheumatic fever: This is a complication that results 2–6 weeks after a group A streptococcal infection of the upper respiratory tract. It presents in developing countries, where antibiotic treatment of streptococcal infections is less common, as a febrile illness with several clinical manifestations, which are organized into what is called the Jones criteria. These criteria include arthritis, carditis, neurological issues, and skin findings. Diagnosis also depends on evidence of a prior group A streptococcal infection in the upper respiratory tract (as seen in streptococcal pharyngitis and scarlet fever). The carditis is the result of the immunologic response targeting the persons heart tissue, and it is the most serious sequelae that develops from acute rheumatic fever. When this involvement of the heart tissue occurs, it is called rheumatic heart disease. In most cases of rheumatic heart disease, the mitral valve is affected, ultimately leading to mitral stenosis. The link to rheumatic fever and heart disease is a particular concern in Australia, because of the high prevalence of these diseases in Aboriginal and Torres Strait Islander communities. Poststreptococcal glomerulonephritis: This is inflammation of the kidney, which presents 1–2 weeks after a group A streptococcal pharyngitis.