Serum sickness

Signs and symptoms can take as long as 14 days after exposure to appear. They may include signs and symptoms commonly associated with hypersensitivity or infections. Common symptoms include: • rashes and redness. • itching and urticaria. • joint pain (arthralgia), especially in finger and toe joints. • fever, usually appears before rash. This may be as high as 40 °C (104 °F). • lymphadenopathy (swelling of lymph nodes), particularly near the site of injection. • malaise. Other symptoms include glomerulonephritis, blood in the urine, splenomegaly (enlarged spleen), hypotension (decreased blood pressure), and in serious cases circulatory shock. Complications Rarely, serum sickness can have severe complications. These include neuritis, myocarditis, laryngeal oedema, pleurisy, and Guillain–Barré syndrome. == Causes ==

Serum sickness is a type III hypersensitivity reaction, caused by immune complexes. The result is a leukocytoclastic vasculitis. == Diagnosis ==

Diagnosis is based on history given by patient, including recent medications. A blood sample may be taken and tested, which will show thrombocytopenia (low platelets), leukopenia (low white blood cells), high sedimentation of red blood cells, and a decrease in the complement proteins C3 and C4. A urine sample may be taken and tested, which will show proteinuria, and sometimes hematuria (blood in the urine, with hemoglobinuria). Differential diagnosis Similar skin symptoms may be caused by lupus, erythema multiforme, and hives. == Prevention ==

Avoidance of antitoxins that may cause serum sickness is the best way to prevent serum sickness. Skin testing may be used beforehand in order to identify individuals who may be at risk of a reaction. Physicians should make their patients aware of the drugs or antitoxins to which they are allergic if there is a reaction. The physician will then choose an alternate antitoxin if it is appropriate, or continue with prophylactic measures. This is important if a patient has received an antitoxin before, as the serum sickness caused can be worse and occur more quickly. == Treatment ==

Antiserum or drug treatment should be stopped as soon as possible. == Epidemiology ==

Serum sickness is becoming less common over time. Many drugs based on animal serum have been replaced with artificial drugs. == History ==

Serum sickness was first characterized by Clemens von Pirquet and Béla Schick in 1905. == See also ==