The symptoms of serum sickness typically occur 7 to 21 daysafter the administration of drugs, foreign proteins, or infections.Symptom onset may be more rapid (within 1 to 4 days) in previously sensitized individuals. The classic clinical manifestationsconsist of fever, polyarticular arthralgias, lymphadenopathy, andcutaneous symptoms. Cutaneous lesions vary and may includeurticaria, angioedema, erythema multiforme, morbilliformrash, and a palpable purpura or serpiginous rash at the interfaceof the dorsal and palmar or plantar aspects of the hands and feet.
Carditis, glomerulonephritis, Guillain-Barre syndrome, encephalomyelitis, and peripheral neuritis are rare complications.
Laboratory tests may show an elevated erythrocyte sedimentation rate, presence of circulating immune complexes, and depressed complement (C3 and C4) levels. Skin biopsy specimens show immune deposits of IgM, IgA, IgE, or C3. Hematuria or proteinuria or both may be present. The diagnosis is established by history of exposure to an inciting cause, characteristic clinical manifestations, and laboratory testing showing circulating immune complexes and depressed complement levels.
Serum sickness is self-limited and resolves within 1 to 2 weeks; therefore, treatment is symptomatic relief. Antihistamines may be administered to relieve pruritus. Nonsteroidal anti-inflammatory drugs are given for fever and joint pain, and, if necessary, prednisone (1 to 2 mg/kg orally daily) is administered with a tapering dose. Allergy skin testing does not predict the likelihood of serum sickness development.
The primary means of prevention is to avoid exposure to the implicated cause.
Systemic allergic reactions usually result from stinging insectsof the order Hymenoptera, which include apids (honeybee and bumblebee), vespids (yellow jacket, wasp, yellow-face, and white-face hornets), and formicids (fire and harvester ants).Honeybees have a barbed stinger that remains embedded aftera sting. Yellow jackets are responsible for most allergic reactions in most parts of the United States, whereas wasps are themost frequent cause of sting reactions in Texas. Fire ants are found in the southeastern and south central United States.
Biting insects rarely cause anaphylaxis. Anaphylaxis has been described, however, after the bites of a kissing bug (Triatoma), bed bug, blackfly, and deerfly. Large local reactions from biting insects, such as mosquitoes, fleas, and flies, are a more common occurrence. The reaction appears urticarial and is caused by the salivary secretions deposited by the biting insect and does not represent an allergic response.
Insect sting allergy may develop at any age and typically manifests after several uneventful stings. Although children are stung more frequently than adults, systemic allergic reactions occur in only about 1% of children and 3% of adults. Reactions in adults are generally more severe than in children and can result in death. Large local reactions to insect stings are more common in children, with an estimated incidence of 20% for children and 10% for adults.
The diagnosis of insect sting allergy is dependent on the history of the reaction and the presence of venom-specific IgE. Normal reactions to insect stings, which are observed in 90%
Large local reaction >2 inches in diameter Swelling contiguous to the site Duration 2–7 days
Nonlife-threatening Immediate generalized reaction confined to the skin (erythema, urticaria, angioedema)
Life-threatening Immediate generalized reaction not confined to the skin with respiratory (laryngeal edema, bronchospasm) or cardiovascular (hypotension, shock) symptoms
Toxic Follows multiple stings, produced by exogenous vasoactive amines in venom