Bothrops atrox, the most important snake involved in human envenomings in the amazon: How venomics contributes to the knowledge of snake biology and clinical toxinology

Long-term hospital care needs after Bothrops atrox envenomation with hemorrhagic stroke in the Brazilian Amazon: 'From social to physical death' - A case report

Hemorrhagic stroke is a severe complication reported in cases of Bothrops atrox snakebite envenomation. We report an unusual case of a patient who evolved with an intracranial hemorrhagic stroke and was in a coma for more than five years in a tertiary hospital located in Manaus, Amazonas. 52-year-old man, carpenter, resident in the rural area of the municipality of Tabatinga, located 1106 km from Manaus, capital of Amazonas, Brazil, victim of an accident involving Bothrops atrox evolution with cardiorespiratory arrest, acute kidney injury and hemorrhagic stroke. After 43 days of hospitalization in the ICU, he was transferred to the ward, without contact with the environment and family, sent for home treatment, however, without acceptance by family members. During a long hospital stay for a period of 6 years, totally dependent on special care, in a flexed position, using a tracheostomy and mechanical ventilation, diagnosed and treated for hospital infections throughout his hospitalization, he died due to bacterial pneumonia. Losses of autonomy can result in an individual being completely disconnected from social life - a "social death before physical death".

Photobiomodulation Therapy to Treat Snakebites Caused by Bothrops atrox: A Randomized Clinical Trial

Importance

Bothrops venom acts almost immediately at the bite site and causes tissue damage.

Objective

To investigate the feasibility and explore the safety and efficacy of low-level laser therapy (LLLT) in reducing the local manifestations of B atrox envenomations.

Design, Setting, and Participants

This was a double-blind randomized clinical trial conducted at Fundação de Medicina Tropical Doutor Heitor Vieira Dourado, in Manaus, Brazil. A total of 60 adult participants were included from November 2020 to March 2022, with 30 in each group. Baseline characteristics on admission were similarly distributed between groups. Data analysis was performed from August to December 2022.

Intervention

The intervention group received LLLT combined with regular antivenom treatment. The laser used was a gallium arsenide laser with 4 infrared laser emitters and 4 red laser emitters, 4 J/cm2 for 40 seconds at each application point.

Main Outcomes and Measures

Feasibility was assessed by eligibility, recruitment, and retention rates; protocol fidelity; and patients' acceptability. The primary efficacy outcome of this study was myolysis estimated by the value of creatine kinase (U/L) on the third day of follow-up. Secondary efficacy outcomes were (1) pain intensity, (2) circumference measurement ratio, (3) extent of edema, (4) difference between the bite site temperature and that of the contralateral limb, (5) need for the use of analgesics, (6) frequency of secondary infections, and (7) necrosis. These outcomes were measured 48 hours after admission. Disability assessment was carried out from 4 to 6 months after patients' discharge. P values for outcomes were adjusted with Bonferroni correction.

Results

A total of 60 patients (mean [SD] age, 43.2 [15.3] years; 8 female individuals [13%] and 52 male individuals [87%]) were included. The study was feasible, and patient retention and acceptability were high. Creatine kinase was significantly lower in the LLLT group (mean [SD], 163.7 [160.0] U/L) 48 hours after admission in relation to the comparator (412.4 [441.3] U/L) (P = .03). Mean (SD) pain intensity (2.9 [2.7] vs 5.0 [2.4]; P = .004), circumference measurement ratio (6.6% [6.6%] vs 17.1% [11.6%]; P < .001), and edema extent (25.8 [15.0] vs 40.1 [22.7] cm; P = .002) were significantly lower in the LLLT group in relation to the comparator. No difference was observed between the groups regarding the mean difference between the bite site temperature and the contralateral limb. Secondary infections, necrosis, disability outcomes, and the frequency of need for analgesics were similar in both groups. No adverse event was observed.

Conclusions and Relevance

The data from this randomized clinical trial suggest that the use of LLLT was feasible and safe in a hospital setting and effective in reducing muscle damage and the local inflammatory process caused by B atrox envenomations.

Trial Registration

Brazilian Registry of Clinical Trials Identifier: RBR-4qw4vf.

Bothrops atrox venom: Biochemical properties and cellular phenotypes of three highly toxic classes of toxins

Snake venoms have a complex mixture of compounds that are conserved across species and act synergistically, triggering severe local and systemic effects. Identification of the toxin classes that are most damaging to cell homeostasis would be a powerful approach to focus on the main activities that underpin envenomation. Here, we focus on the venom of Bothrops atrox, snake responsible for most of the accidents in Amazon region of South America. We identified the key cytotoxic toxin fractions from B. atrox venom and mapped their biochemical properties, protein composition and cell damage. Five fractions were obtained by mass exclusion chromatography and contained either a single class of enzymatic activity (i.e., L-amino acid oxidases or Hyaluronidases) or different activities co-distributed in two or more protein fractions (e.g., Metalloproteinases, Serine Proteases, or Phospholipases A2). Only three protein fractions reduced cell viability of primary human cells. Strikingly, such activity is accompanied by disruption of cell attachment to substratum and to neighbouring cells. Such strong perturbation of morphological cell features indicates likely defects in tissue integrity in vivo. Mass spectrometry identified the main classes of toxins that contribute to these phenotypes. We provide here a strategy for the selection of key cytotoxic proteins for targeted investigation of their mechanism of action and potential synergism during snakebite envenomation. Our data highlights putative toxins (or combinations of) that may be the focus of future therapeutic interference.

Bothrops atrox and Bothrops lanceolatus Venoms In Vitro Investigation: Composition, Procoagulant Effects, Co-Factor Dependency, and Correction Using Antivenoms

Bothrops venoms are rich in enzymes acting on platelets and coagulation. This action is dependent on two major co-factors, i.e., calcium and phospholipids, while antivenoms variably neutralize venom-related coagulopathy effects. Our aims were (i) to describe the composition of B. atrox and B. lanceolatus venoms; (ii) to study their activity on the whole blood using rotational thromboelastometry (ROTEM); (iii) to evaluate the contribution of calcium and phospholipids in their activity; and (iv) to compare the effectiveness of four antivenoms (Bothrofav™, Inoserp™ South America, Antivipmyn™ TRI, and PoliVal-ICP™) on the procoagulant activity of these two venoms. Venom composition was comparable. Both venoms exhibited hypercoagulant effects. B. lanceolatus venom was completely dependent on calcium but less dependent on phospholipids than B. atrox venom to induce in vitro coagulation. The four antivenoms neutralized the procoagulant activity of the two venoms; however, with quantitative differences. Bothrofav™ was more effective against both venoms than the three other antivenoms. The relatively similar venom-induced effects in vitro were unexpected considering the opposite clinical manifestations resulting from envenomation (i.e., systemic bleeding with B. atrox and thrombosis with B. lanceolatus). In vivo studies are warranted to better understand the pathophysiology of systemic bleeding and thrombosis associated with Bothrops bites.

Antibiotic susceptibility of cultivable microbiota from the oral cavity of captive Bothrops atrox and Bothrops lanceolatus: Implications for the treatment of snakebite-associated infections in the French departments of America

INTRODUCTION

Secondary infection is a frequent complication after bites by Bothrops atroxin French Guiana or B. lanceolatus in Martinique. Knowledge of the bacteria present in snake mouths is a valuable aid for determining probabilistic antibiotherapy after Bothrops bite. The objectives of this study were to describe the cultivable bacteria of the oral microbiota of the specimens of B. atrox and B. lanceolatus kept in captivity, and to study their susceptibility to antibiotics.

METHODS

Fifteen B. atrox and 15 B. lanceolatus were sampled. Bacterial cultures were performed and each morphotype on plates was identified using MALDI-TOF mass spectrometry. Antibiotic susceptibility was studied using the agar disk diffusion method, with possible determination of the MICs.

RESULTS

One hundred and twenty-two isolates were identified: 52 isolates and 13 species in B. atrox, 70 isolates and 23 species in B. lanceolatus. The main species were Providencia rettgeri, Morganella morganii, Pseudomonas aeruginosa, Staphylococcus xylosus, and Paeniclostridium sordellii (only in B. lanceolatus mouths). For B. atrox, 96% of isolates were susceptible to piperacillin/tazobactam, cefepime, imipenem and meropenem, 94% to ciprofloxacin and 76% to cefotaxime and ceftriaxone. For B. lanceolatus, 97% of isolates were susceptible to meropenem, 96% to cefepime, 93% to imipenem and piperacillin/tazobactam, 80% to ciprofloxacin, and 75% to cefotaxime and ceftriaxone. Many isolates were resistant towards amoxicillin/clavulanate.

CONCLUSION

Among currently recommended antibiotics, cefepime and piperacillin/tazobactam seem more suitable than cefotaxime or ceftriaxone in the event of a Bothrops bite. Ciprofloxacin may also be considered for B. atrox.

Who are the most affected by Bothrops snakebite envenoming in Brazil? A Clinical-epidemiological profile study among the regions of the country

Snakebite envenoming represents an important Neglected Tropical Disease (NTD) that mainly affects tropical and subtropical developing countries according to the World Health Organization (WHO). As a priority issue in the tropics, it is estimated that accidental encounter between snakes and humans is the leading cause of morbidity and mortality among all NTDs in the world. In Brazil, an extremely diverse country with continental dimensions, snakebite envenoming is the second leading cause of reported human envenoming. Treating the disease has been an unprecedented challenge for Brazilian Health Systems for decades. Despite access to Antivenom therapy and distributing it free of charge across the country, Brazil faces numerous issues regarding the notification process and accurate treatment targeting for at-risk populations. Thus, this study aimed to identify the temporal epidemiological dynamics of accidents caused by Bothrops snakes in Brazil, the country's major group of venomous snakes, based on secondary information from the online database provided by The Brazilian Notifiable Diseases Information System (SINAN). For this purpose, reported Bothrops snakebites between 2012 and 2021 were counted, then the data were analyzed. We looked at the frequency, occurrence, mortality rates, case fatality rate (CFR), age and gender distribution, and the time lapse between the incident and the initiation of Antivenom therapy. The data were also organized considering regional variations of the country. Throughout the studied period, a total of 202,604 cases of envenoming caused by Bothrops spp. were notified, resulting in 766 fatalities. These accidents were found to occur in variable proportions across different regions in Brazil, with notable concentrations observed in the North, Northeast, and Southeast regions. The epidemiological profile of patients varied greatly between the regions, revealing that snake envenoming is much more a social, economic, and ecological problem than a medical one. In conclusion, our study provides an overview of the clinical and epidemiological profile of envenoming by Bothrops snakes in Brazil. Notably, this is the first study to present such information in a country as vast and diverse as Brazil, encompassing a comparative analysis of its regions using SINAN data, that proves to be a very useful national tool to improve the control and management of envenoming.

Prototyping of a lateral flow assay based on monoclonal antibodies for detection of Bothrops venoms

BACKGROUND

Brazil is home to a multitude of venomous snakes; perhaps the most medically relevant of which belong to the Bothrops genus. Bothrops spp. are responsible for roughly 70% of all snakebites in Brazil, and envenomings caused by their bites can be treated with three types of antivenom: bothropic antivenom, bothro-lachetic antivenom, and bothro-crotalic antivenom. The choice to administer antivenom depends on the severity of the envenoming, while the choice of antivenom depends on availability and on how certain the treating physician is that the patient was bitten by a bothropic snake. The diagnosis of a bothropic envenoming can be made based on expert identification of the dead snake or a photo thereof or based on a syndromic approach wherein the clinician examines the patient for characteristic manifestations of envenoming. This approach can be very effective but requires staff that has been trained in clinical snakebite management, which, unfortunately, far from all relevant staff has.

RESULTS

In this article, we describe a prototype of the first lateral flow assay (LFA) capable of detecting venoms from Brazilian Bothrops spp. The monoclonal antibodies for the assay were generated using hybridoma technology and screened in sandwich enzyme-linked immunosorbent assays (ELISAs) to identify Bothrops spp.-specific antibody sandwich pairs. The prototype LFA is able to detect venom from several Bothrops spp. The LFA has a limit of detection (LoD) of 9.5 ng/mL in urine, when read with a commercial reader, and a visual LoD of approximately 25 ng/mL.

SIGNIFICANCE

The work presented here serves as a proof of concept for a genus-specific venom detection kit that could support physicians in diagnosing Bothrops envenomings. Although further optimisation and testing is needed before the LFA can find clinical use, such a device could aid in decentralising antivenoms in the Brazilian Amazon and help ensure optimal snakebite management for even more victims of this highly neglected disease.

Inflammatory Profile Associated with Secondary Infection from Bothrops atrox Snakebites in the Brazilian Amazon

Bothrops snakebite envenomation (SBE) is consider an important health problem in Brazil, where Bothrops atrox is mainly responsible in the Brazilian Amazon. Local effects represent a relevant clinical issue, in which inflammatory signs and symptoms in the bite site represent a potential risk for short and long-term disabilities. Among local complications, secondary infections (SIs) are a common clinical finding during Bothrops atrox SBE and are described by the appearance of signs such as abscess, cellulitis or necrotizing fasciitis in the affected site. However, the influence of SI in the local events is still poorly understood. Therefore, the present study describes for the first time the impact of SBE wound infection on local manifestations and inflammatory response from patients of Bothrops atrox SBE in the Brazilian Amazon. This was an observational study carried out at the Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus (Brazil), involving victims of Bothrops SBE. Clinical and laboratorial data were collected along with blood samples for the quantification of circulating cytokines and chemokines before antivenom administrations (T0) and 24 h (T1), 48 h (T2), 72 h (T3) and 7 days after (T4). From the 94 patients included in this study, 42 presented SI (44.7%) and 52 were without SI (NSI, 55.3%). Patients classified as moderate envenoming presented an increased risk of developing SI (OR = 2.69; CI 95% = 1.08-6.66, p = 0.033), while patients with bites in hands showed a lower risk (OR = 0.20; CI 95% = 0.04-0.96, p = 0.045). During follow-up, SI patients presented a worsening of local temperature along with a sustained profile of edema and pain, while NSI patients showed a tendency to restore and were highlighted in patients where SI was diagnosed at T2. As for laboratorial parameters, leukocytes, erythrocyte sedimentation ratio, fibrinogen and C-reactive protein were found increased in patients with SI and more frequently in patients diagnosed with SI at T3. Higher levels of circulating IL-2, IL-10, IL-6, TNF, INF-γ and CXCL-10 were observed in SI patients along with marked correlations between these mediators and IL-4 and IL-17, showing a plurality in the profile with a mix of Th1/Th2/Th17 response. The present study reports for the first time the synergistic effects of local infection and envenoming on the inflammatory response represented by local manifestations, which reflected on laboratorial parameters and inflammatory mediators and thus help improve the clinical management of SI associated to Bothrops SBE.

Crosstalk of Inflammation and Coagulation in Bothrops Snakebite Envenoming: Endogenous Signaling Pathways and Pathophysiology

Snakebite envenoming represents a major health problem in tropical and subtropical countries. Considering the elevated number of accidents and high morbidity and mortality rates, the World Health Organization reclassified this disease to category A of neglected diseases. In Latin America, Bothrops genus snakes are mainly responsible for snakebites in humans, whose pathophysiology is characterized by local and systemic inflammatory and degradative processes, triggering prothrombotic and hemorrhagic events, which lead to various complications, organ damage, tissue loss, amputations, and death. The activation of the multicellular blood system, hemostatic alterations, and activation of the inflammatory response are all well-documented in Bothrops envenomings. However, the interface between inflammation and coagulation is still a neglected issue in the toxinology field. Thromboinflammatory pathways can play a significant role in some of the major complications of snakebite envenoming, such as stroke, venous thromboembolism, and acute kidney injury. In addition to exacerbating inflammation and cell interactions that trigger vaso-occlusion, ischemia-reperfusion processes, and, eventually, organic damage and necrosis. In this review, we discuss the role of inflammatory pathways in modulating coagulation and inducing platelet and leukocyte activation, as well as the inflammatory production mediators and induction of innate immune responses, among other mechanisms that are altered by Bothrops venoms.

Acute mesenteric ischemia following lancehead snakebite: an unusual case report in the Northernmost Brazilian Amazon

Snakebites have a great impact in the Brazilian Amazon, being the lancehead Bothrops atrox the species responsible for most accidents, disabilities, and deaths. This study shows a case report of an indigenous patient from the Yanomami ethnicity, male, 33 years-old, envenomed by a B. atrox snake. Envenoming caused by B. atrox are characterized by local manifestations (e.g., pain and edema) and systemic manifestations, mainly coagulation disorders. The indigenous victim was admitted in the main hospital of Roraima and evolved with an unusual complication, an ischemia and necrosis of the proximal ileum, requiring segmental enterectomy with posterior side-to-side anastomosis. The victim was discharge after 27 days of hospitalization with no complaints. Snakebite envenomations may evolve with life-threatening complications, which can be treated by the antivenom following access to a healthcare unit, often late in indigenous population. This clinical case shows the need of strategies that aim improvement in the access to the healthcare by indigenous people, as well as demonstrates an unusual complication that may result from lancehead snakebites. The article also discusses the decentralization of snakebites clinical management to indigenous community healthcare centers to mitigate complications.

Children Growing Up with Severe Disabilities as a Result of Snakebite Envenomations in Indigenous Villages of the Brazilian Amazon: Three Cases and Narratives

Snakebites are a major public health problem in the Brazilian Amazon and may lead to local complications and physical deficiencies. Access to antivenom treatment is poorer in indigenous populations compared to other populations. In this study, we report three cases of long-term severe disabilities as a result of Bothrops atrox snakebites in indigenous children, according to the narratives of the parents. The three cases evolved to compartment syndrome, secondary bacterial infection and extensive necrosis. The cases are associated with delayed antivenom treatment due to very fragmented therapeutic itineraries, which are marked by several changes in means of transport along the route. The loss of autonomy at such an early stage of life due to a disability caused by a snakebite, as observed in this study, may deprive children of sensory and social experiences and of learning their future roles in the community. In common to all cases, there was precarious access to rehabilitation services, which are generally centralized in the state capital, and which leads to a prolonged hospitalization of patients with severe snakebite, and distances them from their territory and family and community ties. Prospective studies should be conducted in the Amazon that estimate the burden of disabilities from snakebites in order to formulate public policies for the treatment and rehabilitation of patients through culturally tailored interventions.

Morbidity survey of the history of snakebites in different communities in the alto Juruá, western Brazilian Amazon

The Alto Juruá region has a rich diversity of venomous snakes, and snakebites represent an important cause of morbidity. The present study was carried out in five communities in the Alto Juruá region, and aimed to evaluate the history of snakebites in terms of which snakes were involved and what was the victims' conduct in relation to first aid and prevention. Between 2017 and 2019, semi-structured interviews were applied to 260 residents, 56 (21.53%) of whom had a history of snakebites. The profile of the victims is 73.2% male, a resident of rural areas who develops activities mainly in agriculture and extractivism and who has a low level of education. Just over half of the snakebites occurred during the rainy season (52.8%) and the majority during the day (77%). Bothrops bites were the most frequently reported (90.3%) and B. atrox was the most mentioned snake (jararaca and surucucu) for being responsible for snakebites (80.8%). Approximately 87.5% of the bites occurred to the lower limbs, and 48.2% of the victims were barefoot at the time of the bite. Inadequate first-aid procedures were reported, such as using tourniquets and consuming the drink known as "Específico Pessoa", not drinking water, and treatment with traditional therapy (phytotherapics, zootherapeutics and faith healers), as well as not seeking hospital care. Thus, the need to facilitate access to hospital units in these communities and health education (prevention and first aid) are essential in order to minimize this situation.

Bothrops (Fer-de-lance) snakebites in the French departments of the Americas (Martinique and Guyana): Clinical and experimental studies and treatment by immunotherapy

Snakebite envenomation is a relevant medical hazard in French Guiana and Martinique, two French territories in the Americas. All snakebite envenomations in Martinique are inflicted by the endemic viperid species Bothrops lanceolatus, whereas Bothrops atrox is responsible for the majority of snakebites in French Guiana, although other venomous snake species also occur in this South American territory. This review summarizes some of the key aspects of the natural history of these species, as well as of their venom composition, the main clinical manifestations of envenomations, and their treatment by antivenoms. B. atrox venom induces the typical set of clinical manifestations characteristic of Bothrops sp. venoms, i.e., local tissue damage and systemic alterations associated with coagulopathies, hemorrhage, hemodynamic alterations, and acute kidney injury. In the case of B. lanceolatus venom, in addition to some typical features of bothropic envenomation, a unique and severe thrombotic effect occurs in some patients. The pathogenesis of this effect remains unknown but may be related to the action of venom components and inflammatory mediators on endothelial cells in the vasculature. A monospecific antivenom has been successfully used in Martinique to treat envenomations by B. lanceolatus. In the case of French Guiana, a polyvalent antivenom has been used for some years, but it is necessary to assess the preclinical and clinical efficacy against viperid venoms in this country of other antivenoms manufactured in the Americas.

Feeding ecology of the Terciopelo pit viper snake (Bothrops asper) in Ecuador

Thoroughly documenting prey items and diet composition is crucial for understanding a predator's role in the ecosystem. In gape restricted predators, such as snakes, documenting and analyzing the type and size of the prey is important to interpret their ecological role. We describe the diet patterns of a species of venomous snake, the Terciopelo pit viper (Bothrops asper), from its Ecuadorian populations. Examining the gastrointestinal contents of museum specimens collected over an extensive area of the Pacific lowlands of Ecuador, we encountered 69 identifiable prey items from four major taxonomic groups (amphibians, centipedes, mammals, and reptiles). We evaluated the observed composition of prey to check for differences between sexes and size-classes. To complement our observations of the Terciopelo species complex throughout their distribution, we carried out a systematic literature review. Our data show an ontogenetic shift in diet, with a transition from more diverse diet in juveniles towards a mammal-specialized diet in adults, and distinct proportion of prey taxa between the sexes in the juvenile size class.

Simultaneous identification of three clinically relevant peruvian pit vipers by multiplex loop-mediated isothermal amplification (mLAMP)

Previous knowledge about the taxonomic distribution of venomous snake species is very useful for epidemiological aspects of ophidism. Here, we sought to develop an assay for the differential identification of clinically relevant snakes in Peru: Bothrops atrox, Lachesis muta, and Crotalus durissus using a multiplex loop-mediated isothermal amplification (mLAMP) assay. For this, DNA was extracted from the shed snake skins and the mitochondrial genes Cytb, COI, and 12S rRNA were amplified and further sequenced, for the design of mLAMP reaction primers. For each snake species the forward and reverse primers, internal forward and reverse primers, and the loop primers were obtained, bearing the latter different fluorophores for product identification. Finally, the reaction was standardized in the presence of all primer sets, and an optimal amount of low molecular weight polyethyleneimine. The precipitated products were observed in a UV light transilluminator, finding a differential fluorescence according to the DNA used, with a detection limit to the naked eye in the range of 0.2-25 ng of DNA, within 30 min. This study is the first report on the use of mLAMP technology for the identification of venomous snakes.

A retrospective study of clinical and epidemiological characteristics of snakebite in Napo Province, Ecuadorian Amazon

BACKGROUND

Snakebite envenoming remains a relevant public health problem in tropical and subtropical countries. In Ecuador, this is particularly true in an area of great diversity like the Amazon region. Nevertheless, there is scarce information about epidemiological and clinical characteristics of these accidents in this area.

METHODS

This was a descriptive and retrospective study of snakebite cases treated at a tertiary hospital in the Napo Province, Ecuadorian Amazon, from 2015 to 2019. We collected sociodemographic and snakebite-related information, clinical aspects and the use of antivenom and antibiotics from medical records.

RESULTS

Information from 133 snakebite accidents was reviewed in this time period. Reports of snakebite envenoming decreased over the years. In total, 67% of those bitten were from nearby indigenous communities, which were the most affected groups. When a species was identified, Bothrops atrox was responsible for the highest number of cases registered. Local clinical manifestations were more frequent than systemic signs, in keeping with the typical effects produced by bothropic venoms. Additionally, data showed that more antivenom vials were given than those suggested by the protocol of the Ecuadorian Ministry of Health, in proportion to the grade of severity. Finally, we identified a low incidence of adverse reactions with antivenom administration, as well as a frequent use of antibiotics.

CONCLUSIONS

The profile of snakebite accidents in the Napo Province is very similar to that described for other localities in the Amazon region of Ecuador and neighboring countries, with its challenges and limitations. Such aspects underlie the importance of establishing a robust and science-based public health program to respond to this frequent, but neglected, tropical disease.

Pregnancy outcomes after snakebite envenomations: A retrospective cohort in the Brazilian Amazonia

Snakebite envenomations (SBEs) in pregnant women can result in adverse maternal or neonatal effects, such as abortion, placental abruption, preterm labor, fetal malformations, and maternal, fetal or neonatal deaths. Despite the high incidence of SBEs in the Brazilian Amazon, there is no literature on the impact of SBEs on pregnancy outcomes. The objective of this study was to describe clinical epidemiology and outcomes associated with SBEs in women of childbearing age and pregnant women in the state of Amazonas, Western Brazilian Amazon, from 2007 to 2021. Information on the population was obtained from the Reporting Information System (SINAN), Mortality Information System (SIM) and Live Birth Information System (SINASC) for the period from 2007 to 2021. A total of 36,786 SBEs were reported, of which 3,297 (9%) involved women of childbearing age, and 274 (8.3%) involved pregnant women. Severity (7.9% in pregnant versus 8.7% in non-pregnant women) (P = 0.87) and case-fatality (0.4% in pregnant versus 0.3% in non-pregnant women) rates were similar between groups (P = 0.76). Pregnant women who suffered snakebites were at higher risk for fetal death (OR: 2.17, 95%CI: 1.74-2.67) and neonatal death (OR = 2.79, 95%CI: 2.26-3.40). This study had major limitations related to the completeness of the information on the pregnancy outcomes. Although SBE incidence in pregnant women is low in the Brazilian Amazon, SBEs increased the risk of fetal and neonatal deaths.

Experimental Bothrops atrox Envenomation: Blood Plasma Proteome Effects after Local Tissue Damage and Perspectives on Thromboinflammation

The clinical manifestations of Bothrops atrox envenoming involve local and systemic changes, among which edema requires substantial attention due to its ability to progress to compartmental syndromes and sometimes cause tissue loss and amputations. However, the impact of edema on the poisoned body’s system has not been explored. Thus, the present study aimed to explore the systemic pathological and inflammatory events that are altered by intraplantar injection of B. atrox venom in a mouse model through hematologic, lipidic, and shotgun proteomics analysis. Plasma samples collected showed a greater abundance of proteins related to complement, coagulation, lipid system, platelet and neutrophil degranulation, and pathways related to cell death and ischemic tolerance. Interestingly, some proteins, in particular, Prdx2 (peroxiredoxin 2), Hba (hemoglobin subunit alpha), and F9 (Factor IX), increased according to the amount of venom injected. Our findings support that B. atrox venom activates multiple blood systems that are involved in thromboinflammation, an observation that may have implications for the pathophysiological progression of envenomations. Furthermore, we report for the first time a potential role of Prdx2, Hba, and F9 as potential markers of the severity of edema/inflammation in mice caused by B. atrox.

Diversity of Phospholipases A2 from Bothrops atrox Snake Venom: Adaptive Advantages for Snakes Compromising Treatments for Snakebite Patients

The evolution of snake venoms resulted in multigene toxin families that code for structurally similar isoforms eventually harboring distinct functions. PLA₂s are dominant toxins in viper venoms, and little is known about the impact of their diversity on human envenomings and neutralization by antivenoms. Here, we show the isolation of three distinct PLA₂s from B. atrox venom. FA1 is a Lys-49 homologue, and FA3 and FA4 are catalytic Asp-49 PLA₂s. FA1 and FA3 are basic myotoxic proteins, while FA4 is an acid non-myotoxic PLA₂. FA3 was the most potent toxin, inducing higher levels of edema, inflammatory nociception, indirect hemolysis, and anticoagulant activity on human, rat, and chicken plasmas. FA4 presented lower anticoagulant activity, and FA1 had only a slight effect on human and rat plasmas. PLA₂s presented differential reactivities with antivenoms, with an emphasis on FA3, which was not recognized or neutralized by the antivenoms used in this study. Our findings reveal the functional and antigenic diversity among PLA₂s from B. atrox venom, highlighting the importance of assessing venom variability for understanding human envenomations and treatment with antivenoms, particularly evident here as the antivenom fails to recognize FA3, the most active multifunctional toxin described.

A First Look at the Inhibitory Potential of Urospatha sagittifolia (Araceae) Ethanolic Extract for Bothrops atrox Snakebite Envenomation

Bothrops atrox snakebites are a relevant problem in the Amazon basin. In this biodiverse region, the ethnomedicinal approach plays an important role as an alternative to antivenom therapy. Urospatha sagittifolia (Araceae) is a plant used for this purpose; however, its neutralizing properties have not been scientifically accessed. To fill this gap, we investigated the ability of U. sagittifolia to modulate the catalytic activity of Bothrops atrox venom, and their toxic consequences, such as local damage and lethality. The venom profile of B. atrox was assessed by chromatography and electrophoresis. Inhibition of the three main enzymatic and medically important toxins from the venom was evaluated using synthetic substrates and quantified by chromogenic activity assays. Additionally, the neutralization of lethality, hemorrhage and edema were investigated by in vivo assays. The possible interactions between venom proteins and plant molecules were visualized by polyacrylamide gel electrophoresis. Finally, the phytochemical constituents present in the ethanolic extract were determined by qualitative and quantitative analyses. The ethanolic extract reduced the activity of the three main enzymes of venom target, achieving ranges from 19% to 81% of inhibition. Our in vivo venom neuralizations assays showed a significant inhibition of edema (38.72%) and hemorrhage (42.90%). Additionally, lethality was remarkably counteracted. The highest extract ratio evaluated had a 75% survival rate. Our data support the biomedical value of U. sagittifolia as a source of natural enzyme inhibitors able to neutralize catalytically active B. atrox venom toxins and their toxic effects.

Plant-Derived Toxin Inhibitors as Potential Candidates to Complement Antivenom Treatment in Snakebite Envenomations

Snakebite envenomations (SBEs) are a neglected medical condition of global importance that mainly affect the tropical and subtropical regions. Clinical manifestations include pain, edema, hemorrhage, tissue necrosis, and neurotoxic signs, and may evolve to functional loss of the affected limb, acute renal and/or respiratory failure, and even death. The standard treatment for snake envenomations is antivenom, which is produced from the hyperimmunization of animals with snake toxins. The inhibition of the effects of SBEs using natural or synthetic compounds has been suggested as a complementary treatment particularly before admission to hospital for antivenom treatment, since these alternative molecules are also able to inhibit toxins. Biodiversity-derived molecules, namely those extracted from medicinal plants, are promising sources of toxin inhibitors that can minimize the deleterious consequences of SBEs. In this review, we systematically synthesize the literature on plant metabolites that can be used as toxin-inhibiting agents, as well as present the potential mechanisms of action of molecules derived from natural sources. These findings aim to further our understanding of the potential of natural products and provide new lead compounds as auxiliary therapies for SBEs.

Clinical and Evolutionary Implications of Dynamic Coagulotoxicity Divergences in Bothrops (Lancehead Pit Viper) Venoms

Despite coagulotoxicity being a primary weapon for prey capture by Bothrops species (lancehead pit vipers) and coagulopathy being a major lethal clinical effect, a genus-wide comparison has not been undertaken. To fill this knowledge gap, we used thromboelastography to compare 37 venoms, from across the full range of geography, taxonomy, and ecology, for their action upon whole plasma and isolated fibrinogen. Potent procoagulant toxicity was shown to be the main venom effect of most of the species tested. However, the most basal species (B. pictus) was strongly anticoagulant; this is consistent with procoagulant toxicity being a novel trait that evolved within Bothrops subsequent to their split from anticoagulant American pit vipers. Intriguingly, two of the arboreal species studied (B. bilineatus and B. taeniatus) lacked procoagulant venom, suggesting differential evolutionary selection pressures. Notably, some terrestrial species have secondarily lost the procoagulant venom trait: the Mogi Mirim, Brazil locality of B. alternatus; San Andres, Mexico locality of B. asper; B. diporus; and the São Roque of B. jararaca. Direct action on fibrinogen was extremely variable; this is consistent with previous hypotheses regarding it being evolutionary decoupled due to procoagulant toxicity being the primary prey-capture weapon. However, human patients live long enough for fibrinogen depletion to be clinically significant. The extreme variability may be reflective of antivenom variability, with these results thereby providing a foundation for such future work of clinical relevance. Similarly, the venom diversification trends relative to ecological niche will also be useful for integration with natural history data, to reconstruct the evolutionary pressures shaping the venoms of these fascinating snakes.

Isolated by dry lands: integrative analyses unveil the existence of a new species and a previously unknown evolutionary lineage of Brazilian Lanceheads (Serpentes: Viperidae: Bothrops) from a Caatinga moist-forest enclave

Here we describe a new species of Lancehead (Bothrops jabrensis sp. nov.) based on three individuals sampled from a previously unknown population from Pico do Jabre, an isolated and small Caatinga moist-forest enclave (CMFE) located in northeastern Brazil. Although this new species has an external morphology resembling those found in representatives of the Bothrops jararaca (Wied-Neuwied, 1824) species group, B. jabrensis can be diagnosed by a combination of meristic and color characters. Molecular phylogenetic analysis indicates the new species represents a unique and highly divergent lineage within Bothrops revealing the existence of a previously unknown phylogenetic lineage that has been evolving as an independent unit for more than 8 million years. Additionally, the estimated divergence time of this lineage conflicts with some proposed scenarios of historical processes associated with the evolution of CMFEs. Finally, the uniqueness of this species indicates its relevance for the maintenance of the phylogenetic diversity of Lanceheads in South America. Like other CMFEs, Pico do Jabre is consistently threatened by poaching, illegal fires, deforestation for agricultural purposes, and illegal logging. The restricted distribution of B. jabrensis, in a small and disturbed CMFE, strongly suggests that this species is critically endangered and is likely approaching extinction as a natural population.

Individual Variability in Bothropsatrox Snakes Collected from Different Habitats in the Brazilian Amazon: New Findings on Venom Composition and Functionality

Differences in snake venom composition occur across all taxonomic levels and it has been argued that this variation represents an adaptation that has evolved to facilitate the capture and digestion of prey and evasion of predators. Bothrops atrox is a terrestrial pitviper that is distributed across the Amazon region, where it occupies different habitats. Using statistical analyses and functional assays that incorporate individual variation, we analyzed the individual venom variability in B. atrox snakes from four different habitats (forest, pasture, degraded area, and floodplain) in and around the Amazon River in Brazil. We observed venom differentiation between spatially distinct B. atrox individuals from the different habitats, with venom variation due to both common (high abundance) and rare (low abundance) proteins. Moreover, differences in the composition of the venoms resulted in individual variability in functionality and heterogeneity in the lethality to mammals and birds, particularly among the floodplain snakes. Taken together, the data obtained from individual venoms of B. atrox snakes, captured in different habitats from the Brazilian Amazon, support the hypothesis that the differential distribution of protein isoforms results in functional distinctiveness and the ability of snakes with different venoms to have variable toxic effects on different prey.

Observation of Bothrops atrox Snake Envenoming Blister Formation from Five Patients: Pathophysiological Insights

In the Brazilian Amazon, Bothrops atrox snakebites are frequent, and patients develop tissue damage with blisters sometimes observed in the proximity of the wound. Antivenoms do not seem to impact blister formation, raising questions regarding the mechanisms underlying blister formation. Here, we launched a clinical and laboratory-based study including five patients who followed and were treated by the standard clinical protocols. Blister fluids were collected for proteomic analyses and molecular assessment of the presence of venom and antivenom. Although this was a small patient sample, there appeared to be a correlation between the time of blister appearance (shorter) and the amount of venom present in the serum (higher). Of particular interest was the biochemical identification of both venom and antivenom in all blister fluids. From the proteomic analysis of the blister fluids, all were observed to be a rich source of damage-associated molecular patterns (DAMPs), immunomodulators, and matrix metalloproteinase-9 (MMP-9), suggesting that the mechanisms by which blisters are formed includes the toxins very early in envenomation and continue even after antivenom treatment, due to the pro-inflammatory molecules generated by the toxins in the first moments after envenomings, indicating the need for local treatments with anti-inflammatory drugs plus toxin inhibitors to prevent the severity of the wounds.

Bleeding and Thrombosis: Insights into Pathophysiology of Bothrops Venom-Related Hemostasis Disorders

Toxins from Bothrops venoms targeting hemostasis are responsible for a broad range of clinical and biological syndromes including local and systemic bleeding, incoagulability, thrombotic microangiopathy and macrothrombosis. Beyond hemostais disorders, toxins are also involved in the pathogenesis of edema and in most complications such as hypovolemia, cardiovascular collapse, acute kidney injury, myonecrosis, compartmental syndrome and superinfection. These toxins can be classified as enzymatic proteins (snake venom metalloproteinases, snake venom serine proteases, phospholipases A₂ and L-amino acid oxidases) and non-enzymatic proteins (desintegrins and C-type lectin proteins). Bleeding is due to a multifocal toxicity targeting vessels, platelets and coagulation factors. Vessel damage due to the degradation of basement membrane and the subsequent disruption of endothelial cell integrity under hydrostatic pressure and tangential shear stress is primarily responsible for bleeding. Hemorrhage is promoted by thrombocytopenia, platelet hypoaggregation, consumption coagulopathy and fibrin(ogen)olysis. Onset of thrombotic microangiopathy is probably due to the switch of endothelium to a prothrombotic phenotype with overexpression of tissue factor and other pro-aggregating biomarkers in association with activation of platelets and coagulation. Thrombosis involving large-caliber vessels in B. lanceolatus envenomation remains a unique entity, which exact pathophysiology remains poorly understood.

Snakebites in "Invisible Populations": A cross-sectional survey in riverine populations in the remote western Brazilian Amazon

In the Brazilian Amazon, long distances, low healthcare coverage, common use of ineffective or deleterious self-care practices, and resistance to seeking medical assistance have an impact on access to antivenom treatment. This study aimed to estimate snakebite underreporting, and analyze barriers that prevent victims from obtaining healthcare in communities located in 15 municipalities on the banks of the Solimões, Juruá and Purus Rivers, in the remote Western Brazilian Amazon. Information on the participants' demographics, previous snakebites, access to healthcare, time taken to reach medical assistance, use of self-care practices, and the reason for not accessing healthcare were collected through semi-structured interviews. In the case of deaths, information was collected by interviewing parents, relatives or acquaintances. A total of 172 participants who reported having suffered snakebites during their lifetime were interviewed. A total of 73 different treatment procedures was reported by 65.1% of the participants. Participants living in different river basins share few self-care procedures that use traditional medicine, and 91 (52.9%) participants reported that they had access to healthcare. Living in communities along the Juruá River [OR = 12.6 (95% CI = 3.2-49.7; p<0.001)] and the use of traditional medicine [OR = 11.6 (95% CI = 3.4-39.8; p<0.001)] were variables that were independently associated to the lack of access to healthcare. The main reasons for not accessing healthcare were the pprioritization of traditional treatments (70.4%), and the failure to recognize the situation as being potentially severe (50.6%). Four deaths from complications arising from the snakebite were reported, and three of these were from communities on the banks of the Juruá River. Only one of these received medical assistance. We found an unexpectedly high underreporting of snakebite cases and associated deaths. Snakebite victims utilized three main different healing systems: 1) self-care using miscellaneous techniques; 2) official medical healthcare generally combined with traditional practices; and 3) self-care using traditional practices combined with Western medicines. To mitigate snakebite burden in the Brazilian Amazon, an innovative intervention that would optimize timely delivery of care, including antivenom distribution among existing community healthcare centers, is needed.

Integrating lay knowledge and practice into snakebite prevention and care in central Africa, a hotspot for envenomation

The WHO has identified the goal of halving deaths and disability from snakebite envenomation (SBE) by 2030 through a four-pillar program that promotes accessible and affordable treatments, strengthens health systems, promotes community and multi-level engagement, and mobilizes partnerships, coordination and resources to advocate for global action. This initiative could accelerate multi-disciplinary research and action in central Africa, a “hotspot” for SBE, but it offers little specific guidance about anthropological research to be conducted. This commentary develops that research agenda. It surveys anthropological, ethnohistorical investigations in the central African forest to elaborate the socio-cultural and historical significance and practices around snakes and snakebites. It draws from south and southeast Asian and Latin American literatures to illustrate anthropological contributions to SBE research. It then outlines a Central African research agenda employing ethnobiological investigation of snake ecologies, participatory evaluations of humans-snake contacts, and interviews and participant-observation of local prevention and treatment practices and knowledge. This research will co-develop policies and practices with forest communities and leaders and regional and national authorities to reduce the burden of SBE.

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Central African forests are a hotspot for snakebite envenomation.

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SBE research in central Africa has not mobilized anthropological literatures or methodologies.

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Policies to reduce SBE burden in central Africa should build on participatory research.

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Policies to reduce SBE burden should be co-developed with local and national stakeholders.

Use of freeze-dried trivalent antivenom to neutralize the toxic activities of Bothrops atrox snake venoms from the Amazon

In Brazil, antivenom for snakebite is currently formulated in liquid form and requires storage at 4 °C. Here, a new freeze-dried trivalent antivenom, which would enable cold-chain free storage, was determined to have efficacy in neutralizing the biological activities of Bothrops atrox venoms from Manaus (Brazil) and Leticia (Colombia), exhibiting an efficacy similar to those of currently available liquid Bothrops antivenoms. These results indicate that freeze-dried trivalent antivenom may be beneficial for applications in the Brazilian and Colombian Amazon regions.

A Clot Twist: Extreme Variation in Coagulotoxicity Mechanisms in Mexican Neotropical Rattlesnake Venoms

Rattlesnakes are a diverse clade of pit vipers (snake family Viperidae, subfamily Crotalinae) that consists of numerous medically significant species. We used validated in vitro assays measuring venom-induced clotting time and strength of any clots formed in human plasma and fibrinogen to assess the coagulotoxic activity of the four medically relevant Mexican rattlesnake species Crotalus culminatus, C. mictlantecuhtli, C. molossus, and C. tzabcan. We report the first evidence of true procoagulant activity by Neotropical rattlesnake venom in Crotalus culminatus. This species presented a strong ontogenetic coagulotoxicity dichotomy: neonates were strongly procoagulant via Factor X activation, whereas adults were pseudo-procoagulant in that they converted fibrinogen into weak, unstable fibrin clots that rapidly broke down, thereby likely contributing to net anticoagulation through fibrinogen depletion. The other species did not activate clotting factors or display an ontogenetic dichotomy, but depleted fibrinogen levels by cleaving fibrinogen either in a destructive (non-clotting) manner or via a pseudo-procoagulant mechanism. We also assessed the neutralization of these venoms by available antivenom and enzyme-inhibitors to provide knowledge for the design of evidence-based treatment strategies for envenomated patients. One of the most frequently used Mexican antivenoms (Bioclon Antivipmyn®) failed to neutralize the potent procoagulant toxic action of neonate C. culminatus venom, highlighting limitations in snakebite treatment for this species. However, the metalloprotease inhibitor Prinomastat substantially thwarted the procoagulant venom activity, while 2,3-dimercapto-1-propanesulfonic acid (DMPS) was much less effective. These results confirm that venom-induced Factor X activation (a procoagulant action) is driven by metalloproteases, while also suggesting Prinomastat as a more promising potential adjunct treatment than DMPS for this species (with the caveat that in vivo studies are necessary to confirm this potential clinical use). Conversely, the serine protease inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride (AEBSF) inhibited the direct fibrinogen cleaving actions of C. mictlantecuhtli venom, thereby revealing that the pseudo-procoagulant action is driven by kallikrein-type serine proteases. Thus, this differential ontogenetic variation in coagulotoxicity patterns poses intriguing questions. Our results underscore the need for further research into Mexican rattlesnake venom activity, and also highlights potential limitations of current antivenom treatments.

A painful journey to antivenom: The therapeutic itinerary of snakebite patients in the Brazilian Amazon (The QUALISnake Study)

Access to antivenoms is not guarranteed for vulnerable populations that inhabit remote areas in the Amazon. The study of therapeutic itineraries (TI) for treatment of snakebites would support strategies to provide timely access to users. A TI is the set of processes by which individuals adhere to certain forms of treatment, and includes the path traveled in the search for healthcare, and practices to solve their health problems. This study aims to describe TIs of snakebite patients in the Brazilian Amazon. This study was carried out at the Fundação de Medicina Tropical Doutor Heitor Vieira Dourado, in Manaus, state of Amazonas, Brazil. The itinerary from the moment of the bite to the patient's admission to the reference unit was analyzed. Sample size was defined by saturation. After an exploratory survey to collect epidemiological variables, in-depth interviews were conducted following a semi-structured guide. Patients originated from rural areas of 11 different municipalities, including ones located >500 kilometers from Manaus. A great fragmentation was observed in the itineraries, marked by several changes of means of transport along the route. Four themes emerged from the analysis: exposure to snakebite during day-to-day activities, use of traditional therapeutic practices, and personal perception of the severity, as well as the route taken and its contingencies. Access to healthcare requires considerable effort on the part of snakebite patients. Major barriers were identified, such as the low number of hospitals that offer antivenom treatment, poor access to healthcare due to long distances and geographic barriers, low acceptability of healthcare offered in countryside, lack of use of personal protective equipment, common use of ineffective or deleterious self-care practices, late recognition of serious clinical signs and resistance to seeking medical assistance. Health education, promotion of immediate transport to health centers and decentralization of antivenom from reference hospitals to community healthcare centers in the Brazilian Amazon are more effective strategies that would to maximize access to antivenom treatment.

Severe tissue complications in patients of Bothrops snakebite at a tertiary health unit in the Brazilian Amazon: clinical characteristics and associated factors

INTRODUCTION:

Snakebites in the Brazilian Amazon are caused mostly by snakes from the Bothrops genus and envenomated patients may suffer from tissue complications.

METHODS:

This study aimed to identify risk factors for severe tissue complications (STC) in patients with Bothrops snakebite in the Amazonas state, Brazil.

RESULTS:

Snakebites that were classified as severe and affected female patients with comorbidities presented greater risks of developing STCs. In addition, hospitalizations of patients with STC exceeded 5 days.

CONCLUSIONS:

Clinical and epidemiological characteristics can prove essential for assessing the evolution of STC and clinical prognosis of patients with Bothrops snakebites.

Rapid and Efficient Enrichment of Snake Venoms from Human Plasma Using a Strong Cation Exchange Tip Column to Improve Snakebite Diagnosis

Snake envenomation is a serious public health issue in many tropical and subtropical countries. Accurate diagnosis and immediate antivenom treatment are critical for effective management. However, the venom concentration in the victims' plasma is usually low, representing one of the bottlenecks in developing clinically applicable assays for venom detection and snakebite diagnosis. In this study, we attempted to develop a simple method for rapid enrichment of venom proteins from human plasma to facilitate detection. Our experiments showed that several major protein components of both Naja atra (N. atra) and Bungarus multicinctus (B. multicinctus) venoms have higher isoelectric point (pI) values relative to high-abundance human plasma proteins and could be separated via strong cation exchange-high-performance liquid chromatography (SCX-HPLC). Based on this principle, we developed an SCX tip column-based protocol for rapid enrichment of N. atra and B. multicinctus venom proteins from human plasma. Application of liquid chromatography-tandem mass spectrometry (LC-MS/MS) led to the identification of cytotoxin and beta-bungarotoxin as the major proteins enriched by the SCX tip column in each venom sample. The entire process of venom enrichment could be completed within 10-15 min. Combination of this method with our previously developed lateral flow strip assays (rapid test) significantly enhanced the sensitivity of the rapid test, mainly via depletion of the plasma protein background, as well as increase in venom protein concentration. Notably, the SCX tip column-based enrichment method has the potential to efficiently enrich other Elapidae snake venoms containing proteins with higher pI values, thereby facilitating venom detection with other assays. This simple and rapid sample preparation method should aid in improving the clinical utility of diagnostic assays for snakebite.

Bothrops atrox from Ecuadorian Amazon: Initial analyses of venoms from individuals

Bothrops atrox is the most clinically relevant snake species within the Amazon region, which includes Ecuadorian territories. It comprises a large distribution, which could contribute to the genetic and venomic variation identified in the species. The high variability and protein isoform diversity of its venom are of medical interest, since it can influence the clinical manifestations caused by envenomation and its treatment. However, in Ecuador there is insufficient information on the diversity of venomic phenotypes, even of relevant species such as B. atrox. Here, we characterized the biochemical and toxicological profiles of the venom of six B. atrox individuals from the Ecuadorian Amazon. Differences in catalytic activities of toxins, elution profiles in liquid chromatography, electrophoretic patterns, and toxic effects among the analyzed samples were identified. Nonetheless, in the preclinical testing of antivenom, two samples from Mera (Pastaza) required a higher dose to achieve total neutralization of lethality and hemorrhage. Taken together, these data highlight the importance of analyzing individual venoms in studies focused on the outcomes of envenoming.

Association of cfDNA levels and bothrops envenomation

In the Amazon, around 90% of snakebites are caused by the Bothrops genus. Complications arising from Bothrops envenomations result from the inflammatory and coagulotoxic activities of the venom. The aim of this study was to investigate the potential of cell-free DNA (cfDNA) as a biomarker of severity in Bothrops snakebites. Patients were treated at the Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, in the Brazilian Amazon. cfDNA plasma levels were measured by amplifying the human telomerase reverse transcriptase (hTERT) sequence using quantitative RT-PCR. Median levels of cfDNA were compared between envenomed and healthy volunteers and among patients presenting different complications, such as renal failure, bleeding and infection. Of the 76 patients included, 82.9% were male, with a mean age of 32.8 years, and envenomations were mainly classified as severe (39.5%). ROC curve analysis showed a good accuracy of cfDNA levels (AUROC of 0.745) in envenomation diagnosis. A correlation analysis using laboratory variables showed positive correlation with lactate dehydrogenase (p = 0.033) and platelet count (p = 0.003). When cfDNA levels were compared with clinical complications, significant statistical differences were only found among individuals with mild and severe pain (p < 0.05). In summary, our results demonstrated that cfDNA levels are sufficiently accurate for discriminating between envenomed and non-envenomed patients, but are not able to distinguish different complications and the level of severity among envenomed patients. Thus, the role of cfDNA in the pathogenesis of the snakebite envenomations needs to be further investigated.

Pan-American Lancehead Pit-Vipers: Coagulotoxic Venom Effects and Antivenom Neutralisation of Bothrops asper and B. atrox Geographical Variants

The toxin composition of snake venoms and, thus, their functional activity, can vary between and within species. Intraspecific venom variation across a species’ geographic range is a major concern for antivenom treatment of envenomations, particularly for countries like French Guiana that lack a locally produced antivenom. Bothrops asper and Bothrops atrox are the most medically significant species of snakes in Latin America, both producing a variety of clinical manifestations, including systemic bleeding. These pathophysiological actions are due to the activation by the venom of the blood clotting factors Factor X and prothrombin, thereby causing severe consumptive coagulopathy. Both species are extremely wide-ranging, and previous studies have shown their venoms to exhibit regional venom variation. In this study, we investigate the differential coagulotoxic effects on human plasma of six venoms (four B. asper and two B. atrox samples) from different geographic locations, spanning from Mexico to Peru. We assessed how the venom variation of these venom samples affects neutralisation by five regionally available antivenoms: Antivipmyn, Antivipmyn-Tri, PoliVal-ICP, Bothrofav, and Soro Antibotrópico (SAB). The results revealed both inter- and intraspecific variations in the clotting activity of the venoms. These variations in turn resulted in significant variation in antivenom efficacy against the coagulotoxic effects of these venoms. Due to variations in the venoms used in the antivenom production process, antivenoms differed in their species-specific or geographical neutralisation capacity. Some antivenoms (PoliVal-ICP, Bothrofav, and SAB) showed species-specific patterns of neutralisation, while another antivenom (Antivipmyn) showed geographic-specific patterns of neutralisation. This study adds to current knowledge of Bothrops venoms and also illustrates the importance of considering evolutionary biology when developing antivenoms. Therefore, these results have tangible, real-world implications by aiding evidence-based design of antivenoms for treatment of the envenomed patient. We stress that these in vitro studies must be backed by future in vivo studies and clinical trials before therapeutic guidelines are issued regarding specific antivenom use in a clinical setting.

Size Matters: An Evaluation of the Molecular Basis of Ontogenetic Modifications in the Composition of Bothrops jararacussu Snake Venom

Ontogenetic changes in venom composition have been described in Bothrops snakes, but only a few studies have attempted to identify the targeted paralogues or the molecular mechanisms involved in modifications of gene expression during ontogeny. In this study, we decoded B. jararacussu venom gland transcripts from six specimens of varying sizes and analyzed the variability in the composition of independent venom proteomes from 19 individuals. We identified 125 distinct putative toxin transcripts, and of these, 73 were detected in venom proteomes and only 10 were involved in the ontogenetic changes. Ontogenetic variability was linearly related to snake size and did not correspond to the maturation of the reproductive stage. Changes in the transcriptome were highly predictive of changes in the venom proteome. The basic myotoxic phospholipases A₂ (PLA₂s) were the most abundant components in larger snakes, while in venoms from smaller snakes, PIII-class SVMPs were the major components. The snake venom metalloproteinases (SVMPs) identified corresponded to novel sequences and conferred higher pro-coagulant and hemorrhagic functions to the venom of small snakes. The mechanisms modulating venom variability are predominantly related to transcriptional events and may consist of an advantage of higher hematotoxicity and more efficient predatory function in the venom from small snakes.

Providing Antivenom Treatment Access to All Brazilian Amazon Indigenous Areas: 'Every Life Has Equal Value'

Snakebites are more frequent in the Brazilian Amazon than in other parts of Brazil, representing a high cost for the health system since antivenoms are only available through medical prescription from central municipal hospitals in most cases. The need for a cold chain and physicians usually restricts access to the only effective treatment of a snakebite, the antivenom. The complex topography of the rivers contributes to delays in treatment, and consequently increases the risk of severe complications, chronic sequelae and death. Thus, decentralization of antivenom treatment to primary healthcare facilities in the interior would increase access by indigenous population groups to proper healthcare. To standardize and evaluate the decentralization to low complexity indigenous healthcare units, we suggest the (i) development and validation of standardized operational procedures, (ii) training of professionals in the validated protocol in a referral health unit, (iii) implementation of the protocol in an indigenous healthcare unit, (iv) assessment of perceptions towards and acceptability of the protocol, and (v) estimation of the impact of the protocol's implementation. We expect that antivenom decentralization would shorten the time between diagnosis and treatment and, as such, improve the prognosis of snakebites. As health cosmology among indigenous populations has an important role in maintaining their way of life, the introduction of a new therapeutic strategy to their customs must take into account the beliefs of these peoples. Thus, antivenom administration would be inserted as a crucial therapeutic tool in a world of diverse social, natural and supernatural representations. The information presented here also serves as a basis to advocate for support and promotion of health policy initiatives focused on evidence-based care in snakebite management.

Differential coagulotoxicity of metalloprotease isoforms from Bothrops neuwiedi snake venom and consequent variations in antivenom efficacy

Bothrops (lance-head pit vipers) venoms are rich in weaponised metalloprotease enzymes (SVMP). These toxic enzymes are structurally diverse and functionally versatile. Potent coagulotoxicity is particularly important for prey capture (via stroke-induction) and relevant to human clinical cases (due to consumption of clotting factors including the critical depletion of fibrinogen). In this study, three distinct isoforms of P-III class SVMPs (IC, IIB and IIC), isolated from Bothrops neuwiedi venom, were evaluated for their differential capacities to affect hemostasis of prey and human plasma. Furthermore, we tested the relative antivenom neutralisation of effects upon human plasma. The toxic enzymes displayed differential procoagulant potency between plasma types, and clinically relevant antivenom efficacy variations were observed. Of particular importance was the confirmation the antivenom performed better against prothrombin activating toxins than Factor X activating toxins, which is likely due to the greater prevalence of the former in the immunising venoms used for antivenom production. This is clinically relevant as the enzymes displayed differential potency in this regard, with one (IC) in particular being extremely potent in activating Factor X and thus was correspondingly poorly neutralised. This study broadens the current understanding about the adaptive role of the SVMPs, as well as highlights how the functional diversity of SVMP isoforms can influence clinical outcomes. Key Contribution: Our findings shed light upon the hemorrhagic and coagulotoxic effects of three SVMPs of the P-III class, as well as the coagulotoxic effects of SVMPs on human, avian and amphibian plasmas. Antivenom neutralised prothrombin-activating isoforms better than Factor X activating isoforms.