Leslie V. Boyer

AAPCC database characterization of native U.S. venomous snake exposures, 2001–2005

Background. Differences in victim demographics, clinical effects, managements, and outcomes among native viperid (rattlesnake, copperhead, and cottonmouth) and elapid (coral snake) species have not been systematically characterized. Methods. The database of the American Association of Poison Control Centers from 2001 through 2005 was analyzed. Results. Between 2001 and 2005, there were 23,676 human exposures (average = 4,735/year) to native venomous snakes in the United States reported to U.S. poison centers in all states except Hawaii: 98% were to viperid snakes and 2% to elapids. Overall, 77% of victims were male, 70% were adults >20 years, and 12% were aged less than 10 years. Sixty-five cases involved pregnant women, with rattlesnake bites resulting in moderate or greater effects in over 70%. The overall hospital admission rate was 53%. Outcomes were generally more severe with rattlesnake and copperhead envenomations and in children <6 years of age. The fatality rate of reported cases was 0.06%. Conclusions. Native U.S. venomous snakebite results in considerable morbidity and mortality. Rattlesnake and copperhead envenomations, and those in children <6 years of age, produce the most severe outcomes, but coral snakebites result in similar hospital admission rates.

Relationship of Venom Effects to Venom Antigen and Antivenom Serum Concentrations in a Patient With Crotalus atrox Envenomation Treated With a Fab Antivenom

STUDY OBJECTIVE To describe the association among venom antigenemia, serum antivenom concentrations, and venom effects in a 53-year-old woman who was bitten by a Western Diamondback rattlesnake (Crotalus atrox). METHODS The patient was enrolled in a multicenter trial of an investigational Fab antivenom. Her clinical condition and coagulation parameters were monitored for 2 weeks after the bite. RESULTS After antivenom administration, the progression of the venoms effects was arrested. The antivenom reversed some local venom effects, caused venom antigens to disappear from the blood, and resolved the patients profound thrombocytopenia (before antivenom, 12,000/mm3; 1 hour after antivenom, 227,000/mm3). Local venom effects recurred twice in the 24 hours after antivenom administration but were easily managed with additional Fab antivenom. Venom antigenemia was detected on days 5 and 8 after the initial treatment and was accompanied in one instance by the new onset of hypofibrinogenemia (119 mg/L) that resolved spontaneously and in both instances by renewed profound thrombocytopenia. Repeat Fab antivenom does no days 6 and 9 were followed by increases in platelet count (from 16,000 to 40,000/mm3 and from 11,000 to 20,000/mm3, respectively) and by the reduction or disappearance of venom antigenemia. The patient sustained no significant bleeding complications, and all laboratory values had returned to normal 2 weeks after the bite. CONCLUSION Initial control of local symptoms and coagulopathy was prompt after the administration of Fab antivenom. Repeat doses during the 24 to 36 hours after a bite may be necessary for local control. Recrudescence of coagulopathy was likely due in part to renewed venom antigenemia after clearance of Fab antivenom. The role of Fab antivenom in the treatment of recurrent coagulopathy requires further study.

Cerebral infarction immediately after ingestion of hydrogen peroxide solution.

Background We report the clinical and neuroimaging findings of a patient who sustained multiple cerebral infarcts after the ingestion of concentrated hydrogen peroxide solution sold as a “health food” product. Case Description An 84-year-old man sustained focal neurological deficits immediately after ingesting 30 mL of 35% hydrogen peroxide solution. Physical examination disclosed a left hemiparesis, frontal release signs, and cerebellar dysfunctions. Magnetic resonance imaging revealed multiple cerebral and cerebellar infarctions in the anterior, middle, and posterior vascular territories. Conclusions The likely mechanism of pathogenesis involves cerebral oxygen gas embolization. The use of hyperbaric therapy should be considered in treating hydrogen peroxide poisoning.

Comparison of F(ab')2 versus Fab antivenom for pit viper envenomation: A prospective, blinded, multicenter, randomized clinical trial

Abstract Background. Crotalidae Polyvalent Immune Fab (Ovine) has been the only antivenom commercially available in the US since 2007 for treatment of Crotalinae envenomation. Late coagulopathy can occur or recur after clearance of Fab antivenom, often after hospital discharge, lasting in some cases more than 2 weeks. There have been serious, even fatal, bleeding complications associated with recurrence phenomena. Frequent follow-up is required, and additional intervention or hospitalization is often necessary. F(ab’)2 immunoglobulin derivatives have longer plasma half life than do Fab. We hypothesized that F(ab’)2 antivenom would be superior to Fab in the prevention of late coagulopathy following treatment of patients with Crotalinae envenomation. Methods. We conducted a prospective, double-blind, randomized clinical trial, comparing late coagulopathy in snakebitten patients treated with F(ab’)2 with maintenance doses [F(ab’)2/F(ab’)2], or F(ab’)2 with placebo maintenance doses [F(ab’)2/placebo], versus Fab with maintenance doses [Fab/Fab]. The primary efficacy endpoint was coagulopathy (platelet count < 150 K/mm3, fibrinogen level < 150 mg/dL) between end of maintenance dosing and day 8. Results. 121 patients were randomized at 18 clinical sites and received at least one dose of study drug. 114 completed the study. Of these, 11/37 (29.7%) in the Fab/Fab cohort experienced late coagulopathy versus 4/39 (10.3%, p < 0.05) in the F(ab’)2/F(ab’)2 cohort and 2/38 (5.3%, p < 0.05) in the F(ab’)2/placebo cohort. The lowest heterologous protein exposure was with F(ab’)2/placebo. No serious adverse events were related to study drug. In each study arm, one patient experienced an acute serum reaction and one experienced serum sickness. Conclusions. In this study, management of coagulopathic Crotalinae envenomation with longer-half-life F(ab’)2 antivenom, with or without maintenance dosing, reduced the risk of subacute coagulopathy and bleeding following treatment of envenomation.

Chaparral-Induced Hepatotoxicity

Abstract Background: Chaparral leaf (Larrea tridentata) has been used for centuries to treat a variety of ailments. Laboratory investigations have demonstrated the presence of at least one pharmacologically active lignan, but no controlled studies have demonstrated efficacy and safety in vivo. Recent reports suggest chaparral may cause toxic hepatitis in some chronic users. Case Report: A 27-year-old Hispanic male developed hepatitis approximately 12 months after beginning therapy with chaparral capsules. Liver biopsy showed hepatocellular injury with necrosis and periportal inflammation. Liver function stabilized 6 weeks after hepatitis was first recognized. Conclusions: Although chaparral has been associated with cholangitis, impaired synthetic function and fulminant hepatic failure, because the pattern of chaparral use is unknown, the incidence of hepatotoxicity is also unknown. Severe liver damage may be more common in patients taking higher doses for longer periods of time. Prolonged courses of chaparral should not be recommended routinely. Patients desiring to use chaparral for periods greater than two weeks should be warned of the potential for hepatotoxicity and monitored closely.

Toxic Exposure Surveillance System (TESS)-based characterization of U.S. non-native venomous snake exposures, 1995–2004

Background. Non-native (exotic) snake exposures in the United States have not been systematically characterized. Methods. The Toxic Exposure Surveillance System (TESS) database of the American Association of Poison Control Centers was analyzed to quantify the number and types, demographic associations, clinical presentations, managements and outcomes, and the health resource utilization of non-native snake exposures. Results. From 1995 through 2004, there were 399 non-native exposures in the TESS database. Of these, 350 snakes (87%) were identified by genus and species, comprising at least 77 different varieties. Roughly equal percentages of snakes originated in Asia, Africa and Latin America, with a smaller number from the Middle-East, Australia, and Europe. Nearly half were viperids and a little more than a third were elapids. The vast majority of exposed individuals were adults. However, almost 15% were aged 17 years or less, and almost 7% were children aged 5 years or younger. Eighty-four percent were males. The vast majority of exposures occurred at the victims own residence. Over 50% were evaluated at a healthcare facility, with 28.7% admitted to an ICU. Overall, 26% of patients were coded as receiving antivenom treatment. Coded outcomes were similar between viperid and elapid envenomations. There were three deaths, two involving viperid snakes and one elapid. Enhancements to the TESS database are required for better precision in and more complete characterization of non-native snake envenomations.

Non-Native (Exotic) Snake Envenomations in the U.S., 2005–2011

Non-native (exotic) snakes are a problematic source of envenomation worldwide. This manuscript describes the current demographics, outcomes and challenges of non-native snakebites in the United States (U.S.). We performed a retrospective case series of the National Poison Data System (NPDS) database between 2005 and 2011. There were 258 human exposures involving at least 61 unique exotic venomous species (average = 37 per year; range = 33–40). Males comprised 79% and females 21%. The average age was 33 years with 16% less than 20 years old. 70% of bites occurred in a private residence and 86% were treated at a healthcare facility. 35% of cases received antivenom and 10% were given antibiotics. This study is compared to our previous study (1994–2004) in which there was a substantial coding error rate. Software modifications significantly reduced coding errors. Identification and acquisition of appropriate antivenoms pose a number of logistical difficulties in the management of these envenomations. In the U.S., poison centers have valuable systems and clinical roles in the provision of expert consultation and in the management of these cases.

Is scorpion antivenom cost-effective as marketed in the United States?

PURPOSE The purpose of this study was to analyze the cost-effectiveness of scorpion antivenom compared to no antivenom, in the United States, using a decision analysis framework. METHODS A decision analytic model was created to assess patient course with and without antivenom. Costs were determined from the perspective of a health care payer. Cost data used in the model were extracted from Arizona Medicaid. The probability of clinical events occurring with and without antivenom was obtained from the published literature, medical claims obtained from Arizona Medicaid, and results of recent clinical trials. Patients that became so ill that mechanical ventilator support was necessary were considered treatment failures. A Monte Carlo simulation was run 1000 times and sampled simultaneously across all variable distributions in the model. RESULTS The mean success rate was 99.87% (95% CI 99.64%-99.98%) with scorpion antivenom and 94.31% (95% CI 91.10%-96.61%) without scorpion antivenom. The mean cost using scorpion antivenom was

History of scorpion antivenom: one Arizonan's view.

10,708 (95% CI

Toxicologic information resources for reptile envenomations.

10,556 -