Hematologic Effects Following Crotalinae and Unknown Snake Bites in Northeast Florida

Background: Approximately 5000 snake bites are reported in the United States (US) annually with half of these patients being admitted. Crotalinae species are the most numerous; coral and imported exotic snakes cause a smaller number. Snake venoms are highly stable chemically complex mixtures of proteins. Quantity and composition vary with species and geographic location. Although enzymes contribute to the deleterious effects of the venom, the lethal components may be the smaller low molecular-weight polypeptides. Crotalinae envenomation is known to contain thrombin-like glycoproteins that can induce coagulopathy ranging from asymptomatic lab abnormality to disseminated intravascular coagulopathy (DIC) and life-threatening hemorrhage. In certain geographical areas of the United States thrombocytopenia, hypofibrinogenemia and coagulopathy are common hematological abnormalities, and ones that dictate both a reason for treatment with antivenom as well as an important monitor of therapeutic efficacy. Data on hematological abnormalities following envenomation by crotaline species in Northeast Florida/Southwest Georgia has not been reported before. Methods: We conducted a retrospective review of envenomations that presented to the University of Florida at Jacksonville from April 2013 to October 2018. Patients had to be 16 years or older without any pre-existing hematologic disorder or use of anticoagulant medications. Data including Complete Blood Count, Prothrombin Time (PT), activated Partial Thromboplastin Time (aPTT) and Fibrinogen were measured on presentation, and 4 hours after. Crotaline Fab antivenom (CroFab®) administration was noted if done. Adverse events associated with antivenom therapy, recurrence phenomena, delayed onset of symptoms, and performance of fasciotomy were also recorded. Results: Overall, 119 snakebites were evaluated. The majority were identified as Crotalinae - 25 water moccasin, copperhead or cottonmouth (Agkistrodon piscivorus, Agkistrodon contortrix) bites and 34 rattlesnake (Sistrurus miliarius, Crotalus adamanteus) bites. Male sex dominated the sample with most patients middle-aged (Table 1). More than 80% of patients arrived within 6 hours following the bite. Over 60% of patients received crotaline Fab antivenom. Results are presented in Table 2. Around 12% of patients with water moccasin, copperhead or cottonmouth (Agkistrodon piscivorus, Agkistrodon contortrix) bites had coagulopathy on admission. This compares similarly to data from South Carolina previously showing a 10.89% rate following copperhead bites (Qureshi et al. Blood 2010;116(21):4753). The rate of coagulopathy with rattlesnake bites was however much higher in North Florida at 20.6% - compared to 5.26% in the South Carolina series. Rates of DIC or severe hemorrhage were 8% for water moccasin, copperhead or cottonmouth (Agkistrodon piscivorus, Agkistrodon contortrix) bites and 5.9% for rattlesnake (Sistrurus miliarius, Crotalus adamanteus) bites. When hemostatic defects were looked at separately, the most common abnormality induced was PT/aPTT derangement, followed by hypofibrinogenemia and then thrombocytopenia. This pattern was the same as reported in South Carolina. Recurrence phenomena was observed after 4 hours in a number of patients, however the significance of this remains uncertain as most of these patients remained clinically stable without worsening symptoms. Anaphylactic reaction to the antivenom developed in one patient. Conclusions: In this sample from North Florida, deranged PT/aPTT was the most common hematologic abnormality following envenomation, followed by hypofibrinogenemia and a low rate of thrombocytopenia. Similarities with data from South Carolina were noted, although rattlesnake bites had 4 times higher incidence of coagulopathy in North Florida. DIC or severe hemorrhage was a notable toxicity, affecting 6-8% of Crotalinae cases. Hematologic effects of envenomation do seem to vary by geographic areas in the United States and physicians would benefit from local data to better manage these patients. Disclosures No relevant conflicts of interest to declare.

Comparison of Methods for Measuring Protein Concentration in Venom Samples

Snake venom is an extremely interesting natural mixture of proteins and peptides, characterized by both high diversity and high pharmacological potential. Much attention has been paid to the study of venom composition of different species and also detailed analysis of the properties of individual components. Since proteins and peptides are the active ingredients in venom, rapidly developing proteomic techniques are used to analyze them. During such analyses, one of the routine operations is to measure the protein concentration in the sample. The aim of this study was to compare five methods used to measure protein content in venoms of two snake species: the Viperids representative, Agkistrodon contortrix, and the Elapids representative, Naja ashei. The study showed that for A. contortrix venom, the concentration of venom protein measured by four methods is very similar and only the NanoDrop method clearly stands out from the rest. However, in the case of N. ashei venom, each technique yields significantly different results. We hope that this report will help to draw attention to the problem of measuring protein concentration, especially in such a complex mixture as animal venoms.

Spatial ecology of copperhead snakes (Agkistrodon contortrix) in response to urban park trails

Urban forests and parks are important for recreation and may serve as a natural corridor for commuters. The consequences of human-mediated disturbance in natural areas are documented for avian and mammalian species. Less is known about the consequences of human disturbance on reptile species, specifically snakes, residing in natural refuges within the urban matrix. Thus, we examined the spatial activity of copperheads (Agkistrodon contortrix) in regard to pedestrian trails within an urban forest. We used radio telemetry to track snakes during the active season and estimated distances moved in between relocations, distances to the nearest trail and home range size for individuals. We found sex and season, but not distance to the nearest trail, affected the distance snakes moved. In addition, we observed a weak, positive relationship between home range size and average distance to the trail. Sex, season and body condition did not explain snake distance to the trail, but individual patterns were variable for snakes compared to random locations generated from snake relocations. Our study indicates copperheads may be tolerant of low-level human disturbances found in an urban forest. Further work should be done to quantify levels of disturbance, such as trail use, and compare the behavior of reptiles across urban park types and locations.

ACP-TX-I and ACP-TX-II, Two Novel Phospholipases A2 Isolated from Trans-Pecos Copperhead Agkistrodon contortrix pictigaster Venom: Biochemical and Functional Characterization

This work reports the purification and biochemical and functional characterization of ACP-TX-I and ACP-TX-II, two phospholipases A2 (PLA2) from Agkistrodon contortrix pictigaster venom. Both PLA2s were highly purified by a single chromatographic step on a C18 reverse phase HPLC column. Various peptide sequences from these two toxins showed similarity to those of other PLA2 toxins from viperid snake venoms. ACP-TX-I belongs to the catalytically inactive K49 PLA2 class, while ACP-TX-II is a D49 PLA2, and is enzymatically active. ACP-TX-I PLA2 is monomeric, which results in markedly diminished myotoxic and inflammatory activities when compared with dimeric K49 PLA2s, confirming the hypothesis that dimeric structure contributes heavily to the profound myotoxicity of the most active viperid K49 PLA2s. ACP-TX-II exhibits the main pharmacological actions reported for this protein family, including in vivo local myotoxicity, edema-forming activity, and in vitro cytotoxicity. ACP-TX-I PLA2 is cytotoxic to A549 lung carcinoma cells, indicating that cytotoxicity to these tumor cells does not require enzymatic activity.

Drought-induced Suppression of Female Fecundity in a Capital Breeder

Human-induced global climate change is exerting increasingly strong selective pressures on a myriad of fitness traits that affect organisms. These traits, in turn, are influenced by a variety of environmental parameters such as temperature and precipitation, particularly in ectothermic taxa such as amphibians and reptiles. Over the past several decades, severe and prolonged episodes of drought are becoming commonplace throughout North America. Documentation of responses to this environmental crisis, however, is often incomplete, particularly in cryptic species. Here, we investigated reproduction in a population of pitviper snakes (copperhead, Agkistrodon contortrix), a live-bearing capital breeder. This population experienced a severe drought from 2012 through 2016. We tested whether declines in number of progeny were linked to this drought. Decline in total number offspring was significant, but offspring length and mass were unaffected. Reproductive output was positively impacted by precipitation and negatively impacted by high temperatures. We hypothesized that severe declines of prey species (e.g., cicada, amphibians, and small mammals) reduced energy acquisition during drought, negatively impacting reproductive output of the snakes. Support for this view was found using the periodical cicada (Magicicada spp.) as a proxy for prey availability. Various climate simulations, including our own qualitative analysis, predict that drought events will continue unabated throughout the geographic distribution of copperheads which suggests that long-term monitoring of populations are needed to better understand geographic variation in drought resilience and cascading impacts of drought phenomena on ecosystem function.