Serum sickness is a delayed immune reaction in which the immune system responds to a
protein in antiserum as a potentially harmful substance and mounts an
IgG-mediated antibody response. A 32 year-old female patient had systemic envenoming following a
bite by a red-bellied black snake (Pseudechis porphyriacus). She was treated with Tiger snake
antivenom and recovered over 24 h and did not develop
myotoxicity. She then presented with local
pain,
itching and swelling, which was partially treated with
antihistamines. Eleven days after the
bite she presented again with symptoms of worsening
serum sickness including
rash on the upper legs, joint and
muscle pain in arms, ankles and knees, and
nausea. The patient was prescribed five days of
prednisone 50 mg/day,
antihistamine 10 mg/day and
analgesia 1000 mg/day and improved over 2 days. She had no further problems on follow up at 4 months. This case highlights that
serum sickness can cause significant effects after the treatment of
snake envenoming. It develops 5-14 days after
antivenom administration and has characteristic clinical and laboratory features. Severe cases of
serum sickness can result in morbidity but it appears to respond well to
corticosteroid treatment.