Occupational injuries with captive lance-headed vipers (Bothrops moojeni): experience from a snake farm in Brazil

Acute Severe Anaphylaxis in Nepali Patients with Neurotoxic Snakebite Envenoming Treated with the VINS Polyvalent Antivenom

Diagnosing and treating acute severe and recurrent antivenom-related anaphylaxis (ARA) is challenging and reported experience is limited. Herein, we describe our experience of severe ARA in patients with neurotoxic snakebite envenoming in Nepal. Patients were enrolled in a randomised, double-blind trial of high vs. low dose antivenom, given by intravenous (IV) push, followed by infusion. Training in ARA management emphasised stopping antivenom and giving intramuscular (IM) adrenaline, IV hydrocortisone, and IV chlorphenamine at the first sign/s of ARA. Later, IV adrenaline infusion (IVAI) was introduced for patients with antecedent ARA requiring additional antivenom infusions. Preantivenom subcutaneous adrenaline (SCAd) was introduced in the second study year (2012). Of 155 envenomed patients who received ≥ 1 antivenom dose, 13 (8.4%), three children (aged 5−11 years) and 10 adults (18−52 years), developed clinical features consistent with severe ARA, including six with overlapping signs of severe envenoming. Four and nine patients received low and high dose antivenom, respectively, and six had received SCAd. Principal signs of severe ARA were dyspnoea alone (n=5 patients), dyspnoea with wheezing (n=3), hypotension (n=3), shock (n=3), restlessness (n=3), respiratory/cardiorespiratory arrest (n=7), and early (n=1) and late laryngeal oedema (n=1); rash was associated with severe ARA in 10 patients. Four patients were given IVAI. Of the 8 (5.1%) deaths, three occurred in transit to hospital. Severe ARA was common and recurrent and had overlapping signs with severe neurotoxic envenoming. Optimising the management of ARA at different healthy system levels needs more research. This trial is registered with NCT01284855.

The Ex vivo Eye Irritation Test (EVEIT) model as a mean of improving venom ophthalmia understanding

Snakes belonging to the genus Naja (Elapid family), also known as "spitting cobras", can spit venom towards the eyes of the predator as a defensive strategy, causing painful and potentially blinding ocular envenoming. Venom ophthalmia is characterized by pain, hyperemia, blepharitis, blepharospasm and corneal erosions. Elapid venom ophthalmia is not well documented and no specific treatment exists. Furthermore, accidental ejection of venom by non-spitting vipers, as Bothrops, also occurs. The Ex vivo Eye Irritation Test model (EVEIT) has enabled important progress in the knowledge of chemical ocular burns. Considering the lack of experimental animal model, we adapted the EVEIT to study venom ophthalmia mechanisms. Ex vivo rabbit corneas were exposed to venoms from spitting (Naja mossambica, Naja nigricollis) and non-spitting (Naja naja, Bothrops jararaca and Bothrops lanceolatus) snakes, and rinsed or not with water. The corneal thickness and the depth of damage were assessed using high-resolution optical coherence tomography (HR-OCT) imaging and histological analysis. All Naja venoms induced significant corneal edema, collagen structure disorganization and epithelial necrosis. Corneas envenomed by African N. mossambica and N. nigricollis venoms were completely opaque. Opacification was not observed in corneas treated with venoms from non-spitting snakes, such as the Asian cobra, N. naja, and the vipers, B. jararaca and B. lanceolatus. Moreover, Bothrops venoms were able to damage the epithelium and cause collagen structure disorganization, but not edema. Immediate water rinsing improved corneal status, though damage and edema could still be observed. In conclusion, the present study shows that the EVEIT model was successfully adapted to set a new experimental ex vivo animal model of ophthalmia, caused by snake venoms, which will enable to explore new therapies for venom ophthalmia.

Lys49 myotoxin from the Brazilian lancehead pit viper elicits pain through regulated ATP release

Pain-producing animal venoms contain evolutionarily honed toxins that can be exploited to study and manipulate somatosensory and nociceptive signaling pathways. From a functional screen, we have identified a secreted phospholipase A2 (sPLA2)-like protein, BomoTx, from the Brazilian lancehead pit viper (Bothrops moojeni). BomoTx is closely related to a group of Lys49 myotoxins that have been shown to promote ATP release from myotubes through an unknown mechanism. Here we show that BomoTx excites a cohort of sensory neurons via ATP release and consequent activation of P2X₂ and/or P2X₃ purinergic receptors. We provide pharmacological and electrophysiological evidence to support pannexin hemichannels as downstream mediators of toxin-evoked ATP release. At the behavioral level, BomoTx elicits nonneurogenic inflammatory pain, thermal hyperalgesia, and mechanical allodynia, of which the latter is completely dependent on purinergic signaling. Thus, we reveal a role of regulated endogenous nucleotide release in nociception and provide a detailed mechanism of a pain-inducing Lys49 myotoxin from Bothrops species, which are responsible for the majority of snake-related deaths and injuries in Latin America.

How should occupational anaphylaxis be investigated and managed?

PURPOSE OF REVIEW

Anaphylaxis is a systemic allergic reaction that can be life-threatening or fatal and can result from work-related exposures. This review study focuses on the assessment, main triggers, and management of occupational anaphylaxis.

RECENT FINDINGS

Exposed workers can be sensitized through inhalation and skin contact, and the risks increase with penetration of the allergen through the skin. The main eliciting agents of occupational anaphylaxis include stinging insects and animal bites, natural rubber latex and other vegetable allergens, food products, and drugs. Workers sensitized to occupational allergens may also develop anaphylaxis outside the work environment from exposure to the same or to cross-reacting allergens. Cofactors at work such as exercise may increase the risk. The relevant medical records and laboratory tests (e.g. tryptase) performed during the episode should be reviewed.

SUMMARY

It is very important to confirm the diagnosis and to identify the specific trigger of anaphylaxis. Component-resolved diagnosis may help in the identification of primary sensitizers or cross-reactive allergens. Adrenaline must be administered to all patients experiencing anaphylaxis. Removal from exposure is mandatory to prevent further episodes. A written emergency management plan, health and safety education, and training and surveillance should be enforced in occupations at greater risk.

Comparative analysis of local effects caused by Bothrops alternatus and Bothrops moojeni snake venoms: enzymatic contributions and inflammatory modulations

Bothropic envenomation is characterised by severe local damage caused by the toxic action of venom components and aggravated by induced inflammation. In this comparative study, the local inflammatory effects caused by the venoms of Bothrops alternatus and Bothrops moojeni, two snakes of epidemiological importance in Brazil, were investigated. The toxic action of venom components induced by bothropic venom was also characterised. Herein, the oedema, hyperalgesia and myotoxicity induced by bothropic venom were monitored for various lengths of time after venom injection in experimental animals. The intensity of the local effects caused by B. moojeni venom is considerably more potent than B. alternatus venom. Our results also indicate that metalloproteases and phospholipases A2 have a central role in the local damage induced by bothropic venoms, but serine proteases also contribute to the effects of these venoms. Furthermore, we observed that specific anti-inflammatory drugs were able to considerably reduce the oedema, the pain and the muscle damage caused by both venoms. The inflammatory reaction induced by B. moojeni venom is mediated by eicosanoid action, histamine and nitric oxide, with significant participation of bradykinin on the hyperalgesic and myotoxic effects of this venom. These mediators also participate to inflammation caused by B. alternatus venom. However, the inefficient anti-inflammatory effects of some local modulation suggest that histamine, leukotrienes and nitric oxide have little role in the oedema or myotoxicity caused by B. alternatus venom.

Occupational anaphylaxis--an EAACI task force consensus statement

Anaphylaxis is a systemic allergic reaction, potentially life-threatening that can be due to nonoccupational or, less commonly, to occupational triggers. Occupational anaphylaxis (OcAn) could be defined as anaphylaxis arising out of triggers and conditions attributable to a particular work environment. Hymenoptera stings and natural rubber latex are the commonest triggers of OcAn. Other triggers include food, medications, insect/mammal/snake bites, and chemicals. The underlying mechanisms of anaphylactic reactions due to occupational exposure are usually IgE-mediated and less frequently non-IgE-mediated allergy or nonallergic. Some aspects of work-related allergen exposure, such as route and frequency of exposure, type of allergens, and cofactors may explain the variability of symptoms in contrast to the nonoccupational setting. When assessing OcAn, both confirmation of the diagnosis of anaphylactic reaction and identification of the trigger are required. Prevention of further episodes is important and is based on removal from further exposure. Workers with a history of OcAn should immediately be provided with a written emergency management plan and an adrenaline auto-injector and educated to its use. Immunotherapy is recommended only for OcAn due to Hymenoptera stings.

Challenges in the management of ocular snake-bite injuries

Ocular snake-bite injuries are quite rare away from natural habitats. However, when exotic animals are kept in captivity, the injuries sustained and their management can pose challenges when they present to their local eye department. This report describes an atypical eye injury inflicted by a python and its successful management involving surgical, laser and medical interventions. The case highlights the possible pitfalls resulting from the unusual mechanism of injury and the steps to avoid them. The article goes on to discuss the background of the injuries that can be caused by venomous and non-venomous snakes.

Bothrops snakebite on the head: case report and review of the literature

A previously healthy, 21-year-old female was admitted 5 h after being bitten in the occipital region by a pitviper presumed to be Bothrops jararaca. Physical examination revealed marked cranial and facial oedema extending to the neck and dorsum, bilateral eyelid ecchymosis, and local conjunctival and gingival bleeding. The patient was alert and complained of mild, local pain and nausea. There were no signs of neurological involvement. The main laboratory findings on admission included incoagulable blood, a platelet count of 4000/microl, and an ELISA-estimated serum venom concentration of 62.6 ng/ml. Sequential serum creatinine, urea nitrogen, sodium and potassium concentrations were normal. The case was classified as severe and, after the intravenous administration of ranitidine, chlorpheniramine and hydrocortisone, the intravenous infusion of 12 vials of undiluted bothropic equine antivenom [F(ab)(2); 10 ml/vial] was initiated. The antivenom infusion was halted after 10 vials because the patient developed a severe early reaction, although this was successfully treated with subcutaneous adrenaline and intravenous hydrocortisone. Platelet replacement (seven units) was performed and 24 h after the antivenom infusion, normal results in blood-coagulation tests and an increase in the platelet count (to 100,000/microl) were observed. No circulating venom was detected in blood samples collected 6, 12, 24 or 48 h post-admission. The patient was discharged after 4 days, with clinical improvement and no signs of local infection, and subsequent follow-up revealed no sequelae.

Animal bites and stings with anaphylactic potential

Anaphylaxis to animal bites and stings poses a significant medical risk of vascular or respiratory reactions that vary according to the patient's response and nature of the insult. Emergency Physicians frequently see patients who complain of an allergic reaction to an animal bite or sting. Although Hymenoptera stings, specifically those of wasps, bees, and hornets, account for the majority of these cases, other invertebrates and vertebrates are capable of causing allergic reactions and anaphylaxis. Many of the causative animals are quite unusual, and their bites and stings are not commonly appreciated as potential causes of anaphylaxis. We conducted a literature review to identify documented reports of anaphylaxis and anaphylactoid reactions to animal bites and stings. This summary is meant to heighten awareness of the diversity of animals that may cause anaphylaxis, hopefully leading to more rapid diagnosis and treatment of this dangerous condition. A diverse group of animals was found whose bites and stings cause anaphylaxis and anaphylactoid reactions. Some case summaries are presented. A potentially life-saving plan is to direct patients to proper follow-up care to prevent a future life-threatening reaction, including: prescribing epinephrine and antihistamines with proper instructions for their use; referral to an allergist to determine if skin testing, radioallergosorbent test, and immunotherapy are indicated; and reporting the case to state or local Poison Control Centers. In some cases it may be helpful to consult an entomologist or a pest control service for help in identification and elimination of certain offenders.

Epidemiology of snakebite in a central region of Brazil

The aim of this article is to acquire knowledge about the aspects of snakebite epidemiology in a central region of Brazil. From 1993 to 1995, 90 cases of Crotalinae (Bothrops and Crotalus genera) and two cases of Micrurus snakebite were attended to in a general hospital. Epidemiological information about 73 out of the 90 Crotalinae victims was prospectively collected from interviews with the patients and/or their companions. Data from medical records were obtained for the 17 remaining cases. The snakes of Bothrops, Crotalus, and Micrurus genera were responsible for 74, 24 and 2% of the accidents, respectively. Most of the Crotalinae accidents occurred from October to March (68%) and from 06:00 to 12:00 a.m. (93%). Males (89%) and patients between 20 and 30 years-old (27%) were the most common victims. The main bite sites were: foot (24%), leg (23%), hand (22%) and ankle (21%). Among the 73 interviewed Crotalinae victims, farm workers were bitten more frequently (53%). The accidents often occurred during work (59%), and 90% of the patients wore footwear, but 30% were wearing only sandals. Tourniquet, squeezing, suction of the bite site and magic blessing were attempted in 47, 38, 8 and 10% of cases, respectively.

Unmasking venom gland transcriptomes in reptile venoms

While structural studies of reptile venom toxins can be achieved using lyophilized venom samples, until now the cloning of precursor cDNAs required sacrifice of the specimen for dissection of the venom glands. Here we describe a simple and rapid technique that unmasks venom protein mRNAs present in lyophilized venom samples. To illustrate the technique we have RT-PCR-amplified a range of venom protein transcripts from cDNA libraries derived from the venoms of a hemotoxic snake, the Chinese copperhead (Deinagkistrodon acutus), a neurotoxic snake, the black mamba (Dendroaspis polylepis), and a venomous lizard, the Gila monster (Heloderma suspectum). These include a metalloproteinase and phospholipase A2 from D. acutus, a potassium channel blocker, dendrotoxin K, from D. polylepis, and exendin-4 from H. suspectum. These findings imply that the apparent absence and/or lability of mRNA in complex biological matrices is not always real and paves the way for accelerated acquisition of molecular genetic data on venom toxins for scientific and potential therapeutic purposes without sacrifice of endangered herpetofauna.