Envenomations

Snake Envenomation

Snakebite envenomation (SBE) in horses can have devastating outcomes. Tissue damage, cardiotoxicity, coagulopathy, and neurotoxicity can be concerns with SBE. Understanding the actions of venom components is important in developing a successful treatment plan. Antivenom is the mainstay of treatment. Long-term deleterious effects can occur including cardiac dysfunction and lameness.

[Cerebral-meningeal hemorrhage secondary to snakebite envenomation: about two cases at the Sourô Sanou Teaching Hospital in Bobo-Dioulasso, Burkina Faso]

Background

Envenomation by snakebite is a public health problem in developing countries. Neurovascular complications are uncommon. We report two cases of hemorrhagic stroke at the Sourô Sanou Teaching Hospital in Bobo-Dioulasso, which complicate an envenomation.

Clinical description

The first patient was a 60-year-old woman with no history, who had been admitted 2 hours after snakebite for gingivorrhagia and consciousness disorders. Clinical examination found coma (GCS 7/15) and tetraparesis. The second patient was a 50-year-old woman with no history, who had been admitted one week after snakebite with digestive bleeding. Clinical examination found right hemiplegia and meningeal syndrome. Both patients presented hemorrhagic stroke on brain CT-scan but hemostasis assessment was normal. They received polyvalent antivenom and symptomatic treatment. The outcome was favorable for survival but with sequelae like tetraparesis for first patient and hemiparesis for second patient.

Discussion - Conclusion

The hemorrhagic strokes are rare complications of snake envenomation. Venomous toxins can directly lead to the rupture of intracranial vessels apart of abnormalities of hemostasis. However, the morbidity and mortality related to envenomation by snake bite remains high in our environment.

Rapid purification of a new P-I class metalloproteinase from Bothrops moojeni venom with antiplatelet activity

The present study aimed to evaluate the proteolytic and biological activities of a new metalloproteinase from B. moojeni venom. The purification of BmooMPα-II was carried out through two chromatographic steps (ion-exchange and affinity). BmooMPα-II is a monomeric protein with an apparent molecular mass of 22.5 kDa on SDS-PAGE 14% under nonreducing conditions. The N-terminal sequence (FSPRYIELVVVADHGMFTKYKSNLN) revealed homology with other snake venom metalloproteinases, mainly among P-I class. BmooMPα-II cleaves Aα-chain of fibrinogen followed by Bβ-chain, and does not show any effect on the γ-chain. Its optimum temperature and pH for the fibrinogenolytic activity were 30–50°C and pH 8, respectively. The inhibitory effects of EDTA and 1,10-phenantroline on the fibrinogenolytic activity suggest that BmooMPα-II is a metalloproteinase. This proteinase was devoid of haemorrhagic, coagulant, or anticoagulant activities. BmooMPα-II caused morphological alterations in liver, lung, kidney, and muscle of Swiss mice. The enzymatically active protein yet inhibited collagen, ADP, and ristocetin-induced platelet aggregation in a concentration-dependent manner. Our results suggest that BmooMPα-II contributes to the toxic effect of the envenomation and that more investigations to elucidate the mechanisms of inhibition of platelet aggregation may contribute to the studies of snake venom on thrombotic disorders.

Purification and characterization of BmooAi: a new toxin from Bothrops moojeni snake venom that inhibits platelet aggregation

In this paper, we describe the purification/characterization of BmooAi, a new toxin from Bothrops moojeni that inhibits platelet aggregation. The purification of BmooAi was carried out through three chromatographic steps (ion-exchange on a DEAE-Sephacel column, molecular exclusion on a Sephadex G-75 column, and reverse-phase HPLC chromatography on a C2/C18 column). BmooAi was homogeneous by SDS-PAGE and shown to be a single-chain protein of 15,000 Da. BmooAi was analysed by MALDI-TOF Spectrometry and revealed two major components with molecular masses 7824.4 and 7409.2 as well as a trace of protein with a molecular mass of 15,237.4 Da. Sequencing of BmooAi by Edman degradation showed two amino acid sequences: IRDFDPLTNAPENTA and ETEEGAEEGTQ, which revealed no homology to any known toxin from snake venom. BmooAi showed a rather specific inhibitory effect on platelet aggregation induced by collagen, adenosine diphosphate, or epinephrine in human platelet-rich plasma in a dose-dependent manner, whereas it had little or no effect on platelet aggregation induced by ristocetin. The effect on platelet aggregation induced by BmooAi remained active even when heated to 100°C. BmooAi could be of medical interest as a new tool for the development of novel therapeutic agents for the prevention and treatment of thrombotic disorders.

Wilderness medicine

BACKGROUND

Human activity in wilderness areas has increased globally in recent decades, leading to increased risk of injury and illness. Wilderness medicine has developed in response to both need and interest.

METHODS

The field of wilderness medicine encompasses many areas of interest. Some focus on special circumstances (such as avalanches) while others have a broader scope (such as trauma care). Several core areas of key interest within wilderness medicine are discussed in this study.

RESULTS

Wilderness medicine is characterized by remote and improvised care of patients with routine or exotic illnesses or trauma, limited resources and manpower, and delayed evacuation to definitive care. Wilderness medicine is developing rapidly and draws from the breadth of medical and surgical subspecialties as well as the technical fields of mountaineering, climbing, and diving. Research, epidemiology, and evidence-based guidelines are evolving. A hallmark of this field is injury prevention and risk mitigation. The range of topics encompasses high-altitude cerebral edema, decompression sickness, snake envenomation, lightning injury, extremity trauma, and gastroenteritis. Several professional societies, academic fellowships, and training organizations offer education and resources for laypeople and health care professionals.

CONCLUSIONS

THE FUTURE OF WILDERNESS MEDICINE IS UNFOLDING ON MULTIPLE FRONTS: education, research, training, technology, communications, and environment. Although wilderness medicine research is technically difficult to perform, it is essential to deepening our understanding of the contribution of specific techniques in achieving improvements in clinical outcomes.

Biochemistry of envenomation

Venoms and toxins are of significant interest due to their ability to cause a wide range of pathophysiological conditions that can potentially result in death. Despite their wide distribution among plants and animals, the biochemical pathways associated with these pathogenic agents remain largely unexplored. Impoverished and underdeveloped regions appear especially susceptible to increased incidence and severity due to poor socioeconomic conditions and lack of appropriate medical treatment infrastructure. To facilitate better management and treatment of envenomation victims, it is essential that the biochemical mechanisms of their action be elucidated. This review aims to characterize downstream envenomation mechanisms by addressing the major neuro-, cardio-, and hemotoxins as well as ion-channel toxins. Because of their use in folk and traditional medicine, the biochemistry behind venom therapy and possible implications on conventional medicine will also be addressed.

North American snake envenomation in the dog and cat

Snake envenomation can be a cause of significant morbidity in dogs and cats in North America. Being familiar with the venomous snakes in your area and understanding the mechanisms of action of their venom will allow for successful treatment of envenomation cases. Treatment of snake envenomation revolves around supportive care in mild to moderate cases and venom neutralization with antivenom in severe cases. Dogs and cats envenomated by North American snakes have a good prognosis if treated appropriately.

Is there a role for fasciotomy in Crotalinae envenomations in North America?

CONTEXT

The local effects of Crotalinae envenomation can cause significant tissue destruction, pain, paresthesias, and deformity of the limb, which mimic findings of compartment syndrome, despite rare subfascial penetration of the fangs. Complicating this are the various techniques and ideas about what determines compartment syndrome combined with the fact that elevated intracompartmental pressures have been documented after Crotalinae envenomation, without clear evidence of compartment syndrome or tissue hypoperfusion.

OBJECTIVE

The purpose of this review is to evaluate the North American literature to provide an evidenced-based conclusion about the indications for fasciotomy in Crotalinae envenomations.

METHODS

The search was conducted with studies published only in the English language. The search included all human and animal publications, regardless of the format of study. The Cochrane Central Register, MEDLINE/ Pub Med, Scopus, and Biological Science databases were searched. Citations from all the articles were also cross-referenced if they were pertinent to the review. Major toxicology and emergency medicine and surgical textbooks were also referenced. Abstracts from the North American Congress of Clinical Toxicology, Poisonidex®, and personal articles were also scanned to complete the process, resulting in a total of 640 sources. Papers were excluded if they were duplicates, non-North American, involved excisional therapy, or did not discuss fasciotomy. This left 99 publications applicable to our study.

FINDINGS

No randomized controlled trials, 8 animal experiments, 1 human prospective observational study, 24 retrospective reviews, 32 review articles, 10 case reports, 15 textbooks references, 2 abstracts, and 7 editorials were included in the analysis. Controlled animal experiments show that crotaline Fab antivenin reduces intracompartmental pressure and increases tissue perfusion, while fasciotomy either has no beneficial effect or worsens myonecrosis. The case reports and opinions supporting fasciotomy come from the surgical literature and precede the modern crotaline Fab antivenin.

CONCLUSION

The current evidence does not support the use of fasciotomy or dermotomy following Crotalinae envenomation with elevated intracompartmental pressures. At present, early and adequate administration of crotaline Fab antivenin is the treatment of choice. Fasciotomy cannot be recommended until further well-designed investigations are completed.

Deep soft-tissue necrosis of the foot and ankle caused by catfish envenomation: a case report

Catfish envenomations represent a relatively rare cause of complications in podiatric medicine. We report a case of an unusual event eliciting a severe soft-tissue necrosis in a 21-year-old man and his complicated wound-healing process. This case reviews the potential complications of catfish envenomations.

Antivenin remains effective against African Viperidae bites despite a delayed treatment

BACKGROUND

Viperidae bites represent a public health issue in Africa and are responsible for a hemorrhagic syndrome with fatal outcome in the short term. A research on Medline database does not reveal any data definitively demonstrating the efficiency of antivenom in case of delayed administration. The aim of this study, based on a 12-year survey of viperine syndromes in Republic of Djibouti, was to compare the normalization of the hemostasis disorders with an early administration of antivenin versus a delayed administration.

METHODS

A retrospective study was conducted from October 1994 to May 2006 in the intensive care unit of the French military Hospital, in Djibouti. Seventy-three Viperidae-envenomed patients were included. Antivenin efficiency in correcting hemostatic disorders was analyzed in relation to time to treatment (before or after the 24th hour after the bite).

RESULTS

Forty-two patients (58%) presented with bleeding. A consumptive coagulopathy was found in 68 patients (93%). Antivenin was observed to be effective in improving hemostasis, and the time to normalization of biologic parameters was similar, whether the treatment was started before or after the 24th hour after the bite.

CONCLUSION

Antivenin should ideally be administered as early as possible. However, in Africa, time to treatment generally exceeds 24 hours. The results of the present evidence-based study confirm an empirical concept: a delayed time to treatment should in no way counterindicate the use of antivenin immunotherapy, in the case of African Viperidae bites.

Critical care toxicology

Emergency physicians are regularly called on to care for critically poisoned patients. This article reviews the general approach and management of the critically poisoned patient. Specific clinical characteristics are identified that may clue the clinician into a specific toxin class as a diagnosis. Appropriate testing in the poisoned patient is reviewed. Complications of poisoning that may bring a rapid demise of the critically ill poisoned patient are highlighted and the management of those complications is discussed.

Coagulopathy in patients who experience snakebite

BACKGROUND/AIMS

Coagulopathy is a common complication of snakebite, but there is little information on the clinical importance of coagulopathy. We analyzed the characteristics of coagulopathy after envenomation.

METHODS

Ninety-eight patients who experienced snakebite were enrolled in this study. We divided all the patients into three groups by the ISTH DIC scoring system: the normal, simple coagulopathy and DIC groups. The coagulopathy group included both the simple coagulopathy and DIC groups. We then conducted a case-control study.

RESULTS

There was a significant decrease in the Hct, protein, albumin, ALP and cholesterol levels in the coagulopathy group, and only the cholesterol level was deceased in the DIC group (0<0.05). Leukocytosis and rhabdomyolysis were significantly associated with coagulopathy, and hemolysis and rhabdomyolysis were associated with DIC (p<0.05). The presence of rhabdomyolysis was considered a risk factor for coagulopathy (p<0.05). These conditions continued for up to six to seven days after the snakebite.

CONCLUSIONS

Evaluation of coagulopathy with using these characteristics is helpful to properly manage the patients who experience snakebite.

Skin and soft tissue infections and envenomations acquired at the beach

Millions of people spend vacation and leisure time on the shores of the lakes and oceans of North America. Many others are employed in water-related industries. In doing so, they potentially expose themselves to infections and envenomations that other people do not even consider when making their plans for leisure time activities or in going to work each day. This article reviews some common and uncommon beach-related infections and envenomations that can affect the skin and soft tissues of people frequenting the shores and beaches of North America. Physicians are thereby provided with a guide to such skin and soft tissue injuries and infections and will be better able to recognize and treat these maladies associated with recreational and occupational activities.

The Dapsone hypersensitivity syndrome revisited: a potentially fatal multisystem disorder with prominent hepatopulmonary manifestations

4,4'-Diaminodiphenylsulphone (Dapsone) is widely used for a variety of infectious, immune and hypersensitivity disorders, with indications ranging from Hansen's disease, inflammatory disease and insect bites, all of which may be seen as manifestations in certain occupational diseases. However, the use of dapsone may be associated with a plethora of adverse effects, some of which may involve the pulmonary parenchyma. Methemoglobinemia with resultant cyanosis, bone marrow aplasia and/or hemolytic anemia, peripheral neuropathy and the potentially fatal dapsone hypersensitivity syndrome (DHS), the focus of this review, may all occur individually or in combination. DHS typically presents with a triad of fever, skin eruption, and internal organ (lung, liver, neurological and other systems) involvement, occurring several weeks to as late as 6 months after the initial administration of the drug. In this sense, it may resemble a DRESS syndrome (Drug Rash with Eosinophilia and Systemic Symptoms). DHS must be promptly identified, as untreated, the disorder could be fatal. Moreover, the pulmonary/systemic manifestations may be mistaken for other disorders. Eosinophilic infiltrates, pneumonitis, pleural effusions and interstitial lung disease may be seen. This syndrome is best approached with the immediate discontinuation of the offending drug and prompt administration of oral or intravenous glucocorticoids. An immunological-inflammatory basis of the syndrome can be envisaged, based on the pathological picture and excellent response to antiinflammatory therapy. Since dapsone is used for various indications, physicians from all specialties may encounter DHS and need to familiarize themselves with the salient features about the syndrome and its management.