Serum sickness is a hypersensitivity reaction, similar to an allergic reaction, which occurs in response to a certain antiserum. The body's immune system mistakes a protein in the antiserum as a potentially harmful substance (antigen). The body then develops an immune response against the antiserum.
Antibodies bind with the antiserum protein to create larger particles (immune complexes). The immune complexes are deposited in various tissues, causing inflammation and other symptoms like skin rash, itching, hives, joint pain, arthritis, peripheral neuritis (inflamed peripheral nerve), optic neuritis (inflamed optical nerve), myelitis (inflamed spinal cord), fever, shock, muscle pain, diarrhea, abdominal pain, nausea, vomiting, decreased blood pressure, malaise and enlarged lymph nodes.
Antiserum derived from horse serum and administered as antitoxins or antivenoms are the most common cause of serum sickness. These products are used to treat or prevent rabies, tetanus, botulism and snakebites.
Antiserums derived from horse, rabbit or mouse serum (like antithymocyte globulin, OKT-3) may also cause serum sickness. These preparations are used to treat graft rejection, malignancies (cancerous tumors) or autoimmune diseases.
Other heterologous proteins (derived from more than one animal) may cause serum sickness in some people.
Stings from insects of the order Hymenoptera such as, bees and mosquitoes, as well as tick bites may cause serum sickness.
Exposure to certain medications (especially penicillin) can result in a similar reaction. However, unlike other drug allergies, which occur very soon after receiving the medication for the second (or subsequent) time, serum sickness can develop one to three weeks after the first exposure to a medication. The following drugs may cause serum sickness-like reactions: antibiotics (like cephalosporins, ciprofloxacin, metronidazole, penicillin, rifampicin, streptomycin or tetracycline), antifungals (like itraconazole), antineoplastic agents (like mercaptopurine, procarbazine or thiouracil), anticonvulsants (like carbamazepine or phenytoin), antidepressants (like bupropion or fluoxetine), antidysrhythmics (like procainamide or quinidine), antihypertensives (like captopril, hydralazine, methyldopa or propranolol), anti-inflammatories (like gold salts, indomethacin, naproxen, penicillamine, phenylbutazone, sulindac) and others (like, allopurinol, barbiturates, dextrans, halothane, iodides or methimazole).
Symptoms usually do not develop until one to three weeks after the initial exposure to the antiserum because the body has to produce antibodies to the antigen. However, patients who have been exposed to the offending antigen previously may develop symptoms in one to three days. Symptoms usually last one to two weeks before spontaneously subsiding. Fatalities are rare and usually are the result of continued exposure to the antigen.
Common symptoms include skin rash, itching, hives, joint pain, arthritis, peripheral neuritis (inflamed peripheral nerve), optic neuritis (inflamed optical nerve), myelitis (inflamed spinal cord), fever, shock, muscle pain, diarrhea, abdominal pain, nausea, vomiting, decreased blood pressure, malaise (general feeling of discomfort) and enlarged lymph nodes.
Rare symptoms include: chest pain or breathlessness (resulting from pleuritis, pericarditis, or myocarditis) and encephalitis (inflammation of the brain).
General: In general, laboratory studies are not always helpful in establishing a diagnosis. Symptoms of serum sickness are often similar to other conditions. However, patients who present symptoms of serum sickness and who have recently been exposed to a drug or other product that may cause the reaction should be suspected of having serum sickness. Certain laboratory findings have been reported in patients who have serum sickness, including enlarged lymph nodes, protein or blood in the urine and vasculitis.
Physical examination: If symptoms of serum sickness arise after exposure to antiserum, a qualified healthcare provider should be consulted. During a physical examination a qualified healthcare provider may observe large lymph nodes that are tender to the touch in the patient.
Urine sample: A urine sample may contain blood or proteins.
Blood test: A blood test may indicate vasculitis (inflamed blood vessels).