Development of a double sandwich fluorescent ELISA to detect rattlesnake venom in biological samples from horses with a clinical diagnosis of rattlesnake bite.

Rattlesnake bites in horses are not uncommon and the clinical outcomes are widely variable. Treatment of horses with anti-venom is often cost prohibitive and could have negative consequences; therefore, the development of a quantitative test to determine if anti-venom therapy is indicated would be valuable. The objective of this study was to develop an ELISA to detect rattlesnake venom in biological samples from clinically bitten horses. Nineteen horses were enrolled in the study. Urine was available from 19 horses and bite site samples were available from 9 horses. A double sandwich fluorescent ELISA was developed and venom was detected in 5 of 9 bite site samples and 12 of 19 urine samples. In order to determine if this assay is useful as a guide for treatment, a correlation between venom concentration and clinical outcome needs to be established. For this, first peak venom concentration needs to be determined. More frequent, consistent sample collection will be required to define a venom elimination pattern in horses and determine the ideal sample collection time to best estimate the maximum venom dose. This report describes development of an assay with the ability to detect rattlesnake venom in the urine and at the bite site of horses with a clinical diagnosis of rattlesnake bite.

An examination of serial urinalyses in patients with North American crotalid envenomation.

STUDY OBJECTIVE: To examine the incidence of abnormal urinalyses after rattlesnake envenomations and its association with bite severity and antivenom administration. METHODS: A retrospective review of data collected in a prospective manner for an experimental crotalid antivenom trial. Subjects were individuals with minimal to moderate North American crotalid envenomations. Incidence and characterization of abnormal urinalysis after crotalid envenomation is presented. Additionally, the relationship of abnormal urinalysis to bite severity is examined. A preliminary test of antivenom protein urinalysis interference was also conducted. RESULTS: Forty-three percent of the urinalyses reported prior to antivenom treatment had abnormalities. Thirty-three of 41 subjects (80%) had an abnormal urinalysis, defined as the presence of cells, blood, glucose, or protein, at some time during the 2-week period following envenomation. All but 3 of these subjects had urinalyses which returned to normal by 2 weeks postenvenomation. Fifteen of 22 subjects (68%) with minimal envenomations had an abnormal urinalysis at some time following envenomation, while 18 of 19 subjects (95%) with moderate envenomations had abnormal urinalyses (p < 0.05). In addition, high concentrations of antivenom added to urine were found to produce a positive urine dipstick test for protein. CONCLUSION: In our study of patients with minimal to moderate North American crotalid envenomations, there was a high incidence of abnormal urinalyses. The urine abnormalities tended to be more common with increased bite severity and more frequent during the first few hours following envenomation. Antivenom appearance in the urine could be responsible for some of our findings.

Levels of therapeutic antivenin and venom in a human snakebite victim.

An enzyme-linked immunosorbent assay was used to measure the levels of therapeutic antivenin (Antivenin [Crotalidae] Polyvalent, Wyeth-Ayerst) in serum and the levels of venom in the urine of a patient bitten by a western diamondback rattlesnake (Crotalus atrox). Serum and urine samples were taken on admission, during hospitalization, and during follow-up until 5 months after the bite. Photographs were taken of the bite site on admission to the hospital and during follow-up. Serum levels of therapeutic antivenin were highest between 1 and 3 days after the bite but were still detectable 46 days as well as 4 months after the bite. Crotalus atrox venom was detectable in the urine 4 days after the bite and was still measurable 6 days after the bite.