Serum sickness may be diagnosed based on the symptoms, and using a blood test and a urine test. It may be prevented by not using an antitoxin derived from animal serum, and through prophylactic antihistamines or corticosteroids. It usually resolves naturally, but may be treated with corticosteroids, antihistamines, analgesics, and (in severe cases) prednisone. It was first characterized in 1906.
Signs and symptoms
Signs and symptoms can take as long as 14 days after exposure to appear.[2] They may include signs and symptoms commonly associated with hypersensitivity or infections. Common symptoms include:
Serum sickness is a type III hypersensitivity reaction, caused by immune complexes.[2] When an antiserum is given, the human immune system can mistake the proteins present for harmful antigens. The body produces antibodies, which combine with these proteins to form immune complexes.[2] These complexes precipitate, enter the walls of blood vessels, and activate the complement cascade, initiating an inflammatory response and consuming much of the available complement component 3 (C3). They can be found circulating in the blood, which differentiates serum sickness from serum sickness-like reaction.[4] The result is a leukocytoclastic vasculitis.[2] This results in hypocomplementemia, a low C3 level in serum.[2] They can also cause more reactions, causing the typical symptoms of serum sickness. This is similar to a generalised Arthus reaction.[2]
Antitoxins and antisera
Serum sickness is usually a result of exposure to antibodies derived from animals.[2][3] These sera or antitoxins are generally given to prevent or treat an infection or envenomation (venomous bite).[2]
Allergenic extracts, hormones and vaccines can also cause serum sickness. However, according to the Johns Hopkins Bloomberg School of Public Health, routinely recommended vaccinations to the general population in the U.S have not been shown to cause serum sickness, as of 2012.[5]
Avoidance of antitoxins that may cause serum sickness is the best way to prevent serum sickness.[4] Sometimes, the benefits of using an antitoxin outweigh the risks in the case of a life-threatening bite or sting. Prophylactic antihistamines or corticosteroids may be used with an antitoxin. 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.[4]
Treatment
Antiserum or drug treatment should be stopped as soon as possible.[2][3] Once treatment has stopped, symptoms usually resolve within seven days.[3] Outcomes are generally good.[4]
