Circulating Secretory Phospholipase A2 Activity following Snakebites and Its Relationship with Envenomation Status and Progression of Local Swelling.

We studied whether circulating secretory phospholipase A2 (sPLA2) activity reliably distinguished patients with snakebite envenomation from those with nonvenomous/dry snakebites, and whether patients with progressive local swelling had persistence of circulating sPLA2 activity despite antivenom treatment. We prospectively enrolled adults presenting to the emergency with a history of snakebite in the past 24 hours. We estimated circulating sPLA2 activity at baseline before antivenom administration and after 48 hours in those with envenomation. We enrolled 52 patients with snakebites (mean age 39.3 ± 12.6 years; 35 [67%] men), and 16 patients with infective cellulitis as controls. Thirty patients had local ± systemic envenomation; 15 were classified as dry/nonvenomous bites; and envenomation status was unclear in seven patients. Baseline sPLA2 activity was significantly higher in snakebite patients than that in those with infective cellulitis (4.64 [3.38-5.91] versus 3.38 [1.69-4.01] nmol/minute/mL; P = 0.005). Among patients with snakebites, sPLA2 activity in the highest quartile was significantly associated with envenomation (12 of 27 versus two of 22; P = 0.010). However, median sPLA2 activity did not differ significantly between patients with envenomation and the rest. Baseline sPLA2 activity was significantly associated with the maximum extent of limb swelling (P = 0.031 for trend). In envenomed patients, circulating sPLA2 activity significantly decreased after 48 hours compared with the baseline (5.49 [3.38-8.86] versus 3.38 [2.53-4.64]; P = 0.003) including those with progressive swelling. Although circulating sPLA2 activity was elevated following snakebites, its sensitivity to diagnose envenomation appears to be limited. Administration of more antivenom after systemic manifestations had reversed might not benefit patients with progressive local swelling.