Scorpion envenomations in young children in central Arizona.

INTRODUCTION: 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.

OBJECTIVES: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.