Scorpion envenomations in young children in central Arizona

Centruroides sculpturatus, also known as Centruroides exilicauda or bark scorpion, is the only scorpion native to the United States whose venom produces a potentially life-threatening illness, particularly in children.

To describe the distribution of the severity grades following scorpion envenomations, the onset of clinical signs and symptoms, the time to deterioration, and side effects of antivenom treatment in children < or = 2 yrs of age.

Prospective case-series with the following inclusion criteria of presumed scorpion envenomation, witnessed scorpion or signs and symptoms consistent with envenomation, patient age < or = 2 yrs, and the call was received by the poison center. After data were entered prospectively, a reviewer who was blinded as to the purpose of the study reviewed the charts. A second reviewer examined 10% of the charts for accuracy in coding. Envenomation severity grades were based on a previously described scorpion grading scale and were correlated with admission rates, clinical deterioration, and outcomes. Descriptive statistics (STATA & EXCEL) were used.

Of the 491 charts, 483 (98%) had adequate information available. The mean age was 20.8 [range 2-24] months with 133 patients (27.5%) presenting to an emergency department (ED), 86 patients (17.8%) received antivenom, and 25 patients (5.2%) were admitted. The p-value for kappa and the 95% confidence interval (CI) for interobserver reliability kappa score was 0.69 with CI (0.44-0.95). The grade distributions were Grade I = 343 cases (71%), Grade II = 8 cases (1.7%), Grade III = 49 cases (10.1%), and Grade IV = 83 cases (17.2%). The mean time to advancement of grade was 14 min (95% CI [10.97,17.06], 99% CI [10.04,18.03]) and the median time was < 1 min (range 0-140 min). Twenty-five patients (5.2%) were admitted, of which 13 were Grade III and 12 were Grade IV. Three patients (0.6% of total), all Grade IV envenomations, were intubated (95% CI [0.0021-0.0181] or an upper limit of 8.7 patients). Antivenom was administered to 86 patients (17.8%). The mean time of abatement of symptoms following antivenom was 31 [95% CI 10-82] min vs. 22.2 h [95% CI 12-46]. There was one acute reaction (rash) to antivenom administration and 49 cases (57%) of serum sickness.

Clinical progression following scorpion envenomation in children < or = 2 yrs old occurred on average within 14 min of envenomation with onset almost immediately. Serum sickness occurred in 57% of toddlers receiving antivenom and typically lasted less than 3 days. Admissions were less common among patients receiving antivenom.