Pulmonary effects and complications of snakebites

Dimethyl ester of bilirubin ameliorates Naja naja snake venom-induced lung toxicity in mice via inhibiting NLRP3 inflammasome and MAPKs activation

Naja naja snake bite causes thousands of deaths worldwide in a year. N. naja envenomed victims exhibit both local and systemic reactions that potentially lead to death. In clinical practice, pulmonary complications in N. naja envenomation are commonly encountered. However, the molecular mechanisms underlying N. naja venom-induced lung toxicity remain unknown. Here, we reasoned that N. naja venom-induced lung toxicity is prompted by NLRP3 inflammasome and MAPKs activation in mice. Treatment with dimethyl ester of bilirubin (BD1), significantly inhibited the N. naja venom-induced activation of NLRP3 inflammasome and MAPKs both in vivo and in vitro (p < 0.05). Further, BD1 reduced N. naja venom-induced recruitment of inflammatory cells, and hemorrhage in the lung toxicity examined by histopathology. BD1 also diminished N. naja venom-induced local toxicities in paw edema and myotoxicity in mice. Furthermore, BD1 was able to enhance the survival time against N. naja venom-induced mortality in mice. In conclusion, the present data showed that BD1 alleviated N. naja venom-induced lung toxicity by inhibiting NLRP3 inflammasome and MAPKs activation. Small molecule inhibitors that intervene in venom-induced toxicities may have therapeutic applications complementing anti-snake venom.

Pulmonary involvement from animal toxins: the cellular mechanisms

Venomous animals and their venom have always been of human interest because, despite species differences, coevolution has made them capable of targeting key physiological components of our bodies. Respiratory failure from lung injury is one of the serious consequences of envenomation, and the underlying mechanisms are rarely discussed. This review aims to demonstrate how toxins affect the pulmonary system through various biological pathways. Herein, we propose the common underlying cellular mechanisms of toxin-induced lung injury: interference with normal cell function and integrity, disruption of normal vascular function, and provocation of excessive inflammation. Viperid snakebites are the leading cause of envenomation-induced lung injury, followed by other terrestrial venomous animals such as scorpions, spiders, and centipedes. Marine species, particularly jellyfish, can also inflict such injury. Common pulmonary manifestations include pulmonary edema, pulmonary hemorrhage, and exudative infiltration. Severe envenomation can result in acute respiratory distress syndrome. Pulmonary involvement suggests severe envenomation, thus recognizing these mechanisms and manifestations can aid physicians in providing appropriate treatment.

Pathophysiological and Clinical Significance of Crotalus durissus cascavella Venom-Induced Pulmonary Impairment in a Murine Model

Crotalus venom has broad biological activity, including neurotoxic, myotoxic, hematologic, and cytotoxic compounds that induce severe systemic repercussions. We evaluated the pathophysiological and clinical significance of Crotalus durissus cascavella (Cdc) venom-induced pulmonary impairment in mice. We conducted a randomized experimental study, involving 72 animals intraperitoneally inoculated with saline solution in the control group (CG), as well as venom in the experimental group (EG). The animals were euthanized at predetermined intervals (1 h, 3 h, 6 h, 12 h, 24 h, and 48 h), and lung fragments were collected for H&E and Masson histological analysis. The CG did not present inflammatory alterations in pulmonary parenchyma. In the EG, interstitial and alveolar swelling, necrosis, septal losses followed by alveolar distensions, and areas of atelectasis in the pulmonary parenchyma were observed after three hours. The EG morphometric analysis presented pulmonary inflammatory infiltrates at all time intervals, being more significant at three and six (p = 0.035) and six and 12 h (p = 0.006). The necrosis zones were significant at intervals of one and 24 h (p = 0.001), one and 48 h (p = 0.001), and three and 48 h (p = 0.035). Crotalus durissus cascavella venom induces a diffuse, heterogeneous, and acute inflammatory injury in the pulmonary parenchyma, with potential clinical implications for respiratory mechanics and gas exchange. The early recognition and prompt treatment of this condition are essential to prevent further lung injury and to improve outcomes.

Neurotoxic respiratory failure absent following Arizona rattlesnake bites

Warnings of neurotoxic respiratory paralysis following envenomation by rattlesnakes (Crotalus sp.) have been included in numerous scholarly publications over the past 60 years, resulting in fear and anxiety in the public and among clinicians. We examine the validity of the widespread belief that rattlesnakes in the arid southwestern United States, and particularly the Mohave Rattlesnake (Crotalus scutulatus), pose a significant risk of medically relevant respiratory weakness and paralysis in humans. A retrospective review of 3440 suspected rattlesnake bites reported to the Arizona Poison and Drug Information Center between 1999 and 2020 produced no evidence of respiratory weakness in a region with three species known to express significant amounts of neurotoxin in their venoms: Crotalus concolor, C. tigris, and the more widely distributed C. scutulatus. A literature review produced numerous warnings regarding respiratory paralysis following envenomation by rattlesnakes in our region that either lacked references or cited sources that did not contain strong supportive data. We found no case reports of neurotoxic respiratory weakness following Arizona rattlesnake bites in the literature and such reports in surrounding states were scant. We conclude that neurotoxic respiratory failure in this region following rattlesnake envenomation is extraordinarily rare. All rattlesnake bites should receive the same consideration and critical care, and warnings about significant risk of respiratory failure are unwarranted, regardless of species involved.

Current situation of snakebites envenomation in the Neotropics: Biotechnology, a versatile tool in the production of antivenoms

Snakebite envenomation is a neglected tropical disease that affects millions of people around the world with a great impact on health and the economy. Unfortunately, public health programs do not include this kind of disease as a priority in their social programs. Cases of snakebite envenomations in the Neotropics are inaccurate due to inadequate disease management from medical records to the choice of treatments. Victims of snakebite envenomation are primarily found in impoverished agricultural areas where remote conditions limit the availability of antivenom. Antivenom serum is the only Food and Drug Administration-approved treatment used up to date. However, it has several disadvantages in terms of safety and effectiveness. This review provides a comprehensive insight dealing with the current epidemiological status of snakebites in the Neotropics and technologies employed in antivenom production. Also, modern biotechnological tools such as transcriptomic, proteomic, immunogenic, high-density peptide microarray and epitope mapping are highlighted for producing new-generation antivenom sera. These results allow us to propose strategic solutions in the Public Health Sector for managing this disease. Keywords: antivenom, biotechnology, neglected tropical disease, omics, recombinant antibody.

Practical Review of the Management of Animal Bites

Animal bites are common worldwide. Due to the plethora of animals, there are diverse pathogens with specific associated risks and treatment algorithms. It is crucial to understand these to develop and execute appropriate management plans. This practical review was designed to amalgamate the most common bites worldwide and synthesize data to help guide treatment plans.

METHODS

A PubMed literature search was performed focusing on the major animal bites. High-level studies were preferred and analyzed but lower-level studies were also used if high-level studies did not exist.

RESULTS

The tables presented in this article cover the pertinent information regarding the incidence, common presentation, initial treatment, and potential complications associated with bites from dogs, cats, horses, rodents, snakes, marine life, and spiders. Many of the pathogens associated with the bites are treatable with various and somewhat common antimicrobials, though some are less easy to access. Basic irrigation, debridement, and wound culture are common to almost every animal and should be the first step in treatment.

CONCLUSIONS

Based on the current studies, the most important factor in treating animal bites is timely presentation to a medical facility and/or physician. It is critical that the offending animal be accurately identified to help guide medical and surgical algorithms, including specific antimicrobial treatment guided by the most commonly presenting pathogens specific to certain animals.

Evaluation of systemic inflammatory response and lung injury induced by Crotalus durissus cascavella venom

This study investigated the systemic inflammatory response and mechanism of pulmonary lesions induced by Crotalus durissus cascavella venom in murine in the state of Bahia. In order to investigate T helper Th1, Th2 and Th17 lymphocyte profiles, we measured interleukin (IL) -2, IL-4, IL-6, IL-10, IL-17, tumor necrosis factor (TNF) and interferon gamma (IFN-γ) levels in the peritoneal fluid and macerated lungs of mice and histopathological alterations at the specific time windows of 1h, 3h, 6h, 12h, 24h and 48h after inoculation with Crotalus durissus cascavella venom. The data demonstrated an increase of acute-phase cytokines (IL-6 and TNF) in the first hours after inoculation, with a subsequent increase in IL-10 and IL-4, suggesting immune response modulation for the Th2 profile. The histopathological analysis showed significant morphological alterations, compatible with acute pulmonary lesions, with polymorphonuclear leukocyte (PMN) infiltration, intra-alveolar edema, congestion, hemorrhage and atelectasis. These findings advance our understanding of the dynamics of envenomation and contribute to improve clinical management and antiophidic therapy for individuals exposed to venom.

A life-threatening complication due to pulmonary haemorrhage following hump-nosed viper bite

Background

Hump-nosed viper bite, the commonest venomous snake bite in Sri Lanka, is associated with significant morbidity. Specific anti-venom is not available for hump-nosed viper envenomation which is usually managed with supportive treatment. Pulmonary haemorrhage is an unusual manifestation of hump-nosed viper bite. Here we present a case of hump-nosed viper envenomation which complicated by pulmonary haemorrhage and was successfully treated with systemic steroids. To the best of our knowledge, it has not been reported in the literature before.

Case presentation

A previously healthy 55-year-old man presented to the local hospital 18 h after a hump-nosed viper bite. He developed bilateral severe pulmonary haemorrhages, evidenced by rapid desaturation which needed intubation and mechanical ventilation, bleeding from the endotracheal tube and bilateral alveolar shadows in a chest x-ray. He had no other bleeding manifestations. Because of the life-threatening situation, he was treated with methylprednisolone pulse therapy. There was a rapid improvement of hypoxia with a resolution of x-ray changes. He was successfully weaned off from the ventilation after 24 h.

Conclusion

This case highlights the importance of suspecting pulmonary haemorrhage in a patient who develops desaturation and alveolar shadow following hump-nosed viper bite even in the absence of other bleeding manifestation. Early and timely treatment with systemic steroid can be lifesaving in such patients.

Amplification of Snake Venom Toxicity by Endogenous Signaling Pathways

The active components of snake venoms encompass a complex and variable mixture of proteins that produce a diverse, but largely stereotypical, range of pharmacologic effects and toxicities. Venom protein diversity and host susceptibilities determine the relative contributions of five main pathologies: neuromuscular dysfunction, inflammation, coagulopathy, cell/organ injury, and disruption of homeostatic mechanisms of normal physiology. In this review, we describe how snakebite is not only a condition mediated directly by venom, but by the amplification of signals dysregulating inflammation, coagulation, neurotransmission, and cell survival. Although venom proteins are diverse, the majority of important pathologic events following envenoming follow from a small group of enzyme-like activities and the actions of small toxic peptides. This review focuses on two of the most important enzymatic activities: snake venom phospholipases (svPLA2) and snake venom metalloproteases (svMP). These two enzyme classes are adept at enabling venom to recruit homologous endogenous signaling systems with sufficient magnitude and duration to produce and amplify cell injury beyond what would be expected from the direct impact of a whole venom dose. This magnification produces many of the most acutely important consequences of envenoming as well as chronic sequelae. Snake venom PLA2s and MPs enzymes recruit prey analogs of similar activity. The transduction mechanisms that recruit endogenous responses include arachidonic acid, intracellular calcium, cytokines, bioactive peptides, and possibly dimerization of venom and prey protein homologs. Despite years of investigation, the precise mechanism of svPLA2-induced neuromuscular paralysis remains incomplete. Based on recent studies, paralysis results from a self-amplifying cycle of endogenous PLA2 activation, arachidonic acid, increases in intracellular Ca2+ and nicotinic receptor deactivation. When prolonged, synaptic suppression supports the degeneration of the synapse. Interaction between endothelium-damaging MPs, sPLA2s and hyaluronidases enhance venom spread, accentuating venom-induced neurotoxicity, inflammation, coagulopathy and tissue injury. Improving snakebite treatment requires new tools to understand direct and indirect effects of envenoming. Homologous PLA2 and MP activities in both venoms and prey/snakebite victim provide molecular targets for non-antibody, small molecule agents for dissecting mechanisms of venom toxicity. Importantly, these tools enable the separation of venom-specific and prey-specific pathological responses to venom.

Plasmapheresis for Pulmonary Hemorrhage Following Viperine Snakebite: A Case Report with Review of Literature

Introduction

Snakebites are one of the commonest occupational hazards in tropical countries and viperine bites are potential to cause systemic toxicity. Coagulopathies and acute kidney injury (AKI) have been documented and easily dealt with in past, but pulmonary hemorrhage has been rarely seen and plasmapheresis has shown promising result for the same. This case reports highlight the effective use of plasmapheresis for pulmonary hemorrhage post-snakebite.

Background

Viperine snakebite has been associated with high morbidity and mortality due to its toxic systemic envenomization. The important systemic manifestations are coagulopathy, neuromuscular paralysis, AKI, myotoxicity, and cardiovascular collapse. Antivenomization, renal replacement therapy, steroids, and other supportive care are considered to be the mainstay of treatment till date. Pulmonary hemorrhage has been an unusual manifestation of viper bite and rarely reported and steroids have been used in such scenario but with mixed results. Role of plasmapheresis has been documented in the management of snakebite but especially for hematological problems and in limb preservation/salvage strategies. The use of same, for pulmonary hemorrhage has not been studied yet. Here, we present a rare case of pulmonary hemorrhage along with renal failure following viper bite which was successfully treated with plasmapheresis. To the best of our knowledge, it is a rare presentation and has not been reported in the literature reviewed till date.

Case description

A previously healthy, 36-year-old man presented to our hospital 48 hours after a viper bite. He developed local as well systemic manifestations evident as hemolysis and renal failure. Gradually, he started having hemoptysis followed by respiratory failure requiring ventilatory support. CT chest done was s/o bilateral pulmonary hemorrhages correlating clinically with ongoing tracheal bleed. He had no other bleeding manifestations and had normal coagulation profile. He was initially treated with methylprednisolone therapy, but then did not show any improvement and finally plasmapheresis was done as rescue therapy. Following this, he had improvement in respiratory parameters and settling tracheal bleed with resolution of radiological changes. He was successfully weaned off from the ventilation and also his renal failure also improved with near normalization of pulmonary and renal functions.

Conclusion

This case highlights the unusual presentation of pulmonary hemorrhage in a patient with viperine bite with normal coagulation and was aggressively managed with plasmapheresis. Hence, plasmapheresis can be used as life-saving modality in patients with systemic envenomization post-viperine bit.

How to cite this article

Sampley S, Sakhuja V, Bhasin D, Singh K, Singh H. Plasmapheresis for Pulmonary Hemorrhage Following Viperine Snakebite: A Case Report with Review of Literature. Indian J Crit Care Med 2020;24(10):986-990.

Systemic bleeding including pulmonary haemorrhage following hump-nosed pit viper (Hypnale hypnale) envenoming: A case report from Sri Lanka

Out of seven venomous land snake species of Sri Lanka, hump-nosed pit viper (Hypnale spp.) causes the commonest venomous snakebites. It is widely distributed all over the country except in the peninsula of Jaffna. The genus has three species naming H. hypnale, H. zara and H. nepa. They frequently cause local envenoming and rarely cause coagulopathy and acute kidney injury. Systemic bleeding is the most trivial complication associated with coagulopathy caused by these snakes and pulmonary haemorrhages are one of them which are rarely reported. Antivenoms are currently not available for genus Hypnale bites in Sri Lanka. We describe a fatal case of pulmonary haemorrhage caused by a proven hump-nosed viper (Hypnale hypnale) bite associated with other systemic bleeding manifestations and thrombotic microangiopathy. This is the first known case of pulmonary and intracranial haemorrhages caused by hump-nosed viper bite.