II. Pathophysiology
- Type 3 Hypersensitivity Reaction (Immune Complex-Mediated Reaction)
- Small immune-complex tissue deposition
- Results in Nephritis, Arthritis, Vasculitis
III. History
-
Diphtheria Antitoxin reaction in the early 1900s was the original defining condition
- Antitoxin had historically been harvested from horses who had been injected with Diphtheria toxin
- Similar reactions were seen with Scarlet Fever antitoxin
- Modern day Diphtheria antitoxin is no longer produced in horses and does not cause Serum Sickness
-
Snake Antivenom
- Older Snake Antivenoms were also harvested from horses and resulted in frequent reactions
- Newer Snake Antivenoms (e.g. CroFab) are now produced in sheep and associated with less common reactions
IV. Symptoms
- Onset of symptoms 4-21 days after exposure (mean 8-10 days)
- High Fever spikes
- Pruritic rash (including Urticaria)
- No mucous membrane involvement
- Rash starts in region of original injection
- Lymphadenopathy
- Polyarthralgias
V. Causes
- Equine-based microbial antitoxins (anti-Rabies, anti-botulinum, and anti-diphtheria Immunoglobulin)
- Antivenoms (Snake Antivenom, Anti-Lactrodectus Spider venom)
- Rabies Vaccine
- Stretokinase
- Insect Bite Proteins
- Monoclonal Antibodies (e.g. Rituximab, Infliximab)
VI. Differential Diagnosis
- Rheumatologic Conditions
- Drug Reactions
- Bacterial Syndromes
- Viral syndromes
- Serum Sickness Like Reaction Causes
- Cefaclor (Ceclor)
- Penicillin (high dose IV)
- Amoxicillin
- Trimethoprim-Sulfamethoxazole (Bactrim, Septra)
- Hepatitis B Infection
VII. Labs
-
Complete Blood Count (CBC)
- Neutropenia
- Reactive Lymphocytes
- Mild Thrombocytopenia
- Comprehensive Metabolic Panel
- Transient Serum Creatinine increase may occur
- Acute Phase Reactant elevations
-
Urinalysis
- Mild Proteinuria
VIII. Management
- Withdraw causative agent
- Symptomatic management
- NSAIDs
- Corticosteroids in severe cases
IX. Prevention
- No study (including Skin Test for Horse Serum Sensitivity) predicts Serum Sickness reaction
X. References
- Rixe (2020) Serum Sickness, Stat Pearls, accessed 9/27/2020
- Wener in Adkinson (2020) Serum Sickness and Serum Sickness-like Reactions, UpToDate, accessed 9/27/2020