Exanthem

Definition of Exanthem

Woman itching
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The word exanthem means a skin eruption that bursts forth or blooms. It is typically used to describe a rash that is widespread over the body, symmetric, and red with macules or papules, but without scales. Exanthems are usually caused by viral or bacterial infections. They can also be caused by drugs, toxins or autoimmune diseases. The rash may or may not be itchy.

Exanthems caused by viruses or bacteria often are part of systemic illness with fever, malaise and headache.

The skin rash is triggered by the body's reaction to a toxin produced by the infecting organism, or the immune response the body mounts to the organism, or damage that the organism makes to the skin.

The word exanthem or exanthema comes from a Greek word meaning "a breaking out." It is in contrast with the word enanthem or enanthema, which is a rash on the mucus membranes.

Diagnosing Exanthems

A sudden-appearing, wide-spread rash, especially with fever and malaise is cause for a visit to the doctor or urgent care clinic, as some causes need early treatment. Because of this course of disease, they are often diagnosed by primary care physicians or urgent care providers.

Many of the exanthem rashes have a typical appearance that helps with the differential diagnosis of what disease or process is causing it. It is part of medical training to recognize these rash patterns. But verification can include taking a swab for viral testing or PCR identification.

Blood tests can be done to look for antibodies to specific viruses and bacteria. DNA probes can also identify suspected agents.

Historical Numbering of Exanthems

Exanthems used to be consecutively numbered based on their historical appearance and description.

  • First disease - measles, specifically rubeola, caused by the measles morbillivirus.
  • Second disease - scarlet fever, which occurs after an infection Streptococcus pyogenes (group A streptococcus). This can occur as a throat infection, strep throat.
  • Third disease - rubella or German measles, caused by the rubella virus.
  • Fourth disease - "Dukes' disease" (probably a coxsackievirus or echovirus infection)
  • Fifth disease - erythema infectiosum, caused by parvovirus B19.
  • Sixth disease - roseola infantum, caused by herpesviruses HHV-6 and HHV-7.

Childhood Exanthems

Chickenpox (varicella zoster virus), mumps, and the common cold are exanthems seen in children, as well as these from the classic list: measles, rubella, roseola, erythema infectiosum. Many of these can be prevented by vaccines.

More Viral and Bacterial Exanthems

Viral exanthems beyond those listed include the human immunodeficiency virus (HIV) its acute infection stage. Smallpox, now eradicated produced an exanthem. Viral hepatitis and infectious mononucleosis caused by the Epstein-Barr virus may produce an exanthem.

Bacterial infections producing a widespread rash include the big two - Staphylococcus toxin infections and Streptococcal toxin infections, including toxic shock syndrome and scarlet fever.

Mycoplasma pneumonia, Kawasaki disease, and rickettsial diseases can cause these rashes.

Treating Exanthems

The treatment is based on treating the underlying disease, some of which are life-threatening but others of which only need supportive care or are self-limiting. Treatment to reduce a fever is usually done. Creams may be given to reduce the itch if the rash is itchy.

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