Antivenom for snakebite envenoming in Sri Lanka: The need for geographically specific antivenom and improved efficacy

Snakebite epidemiology, outcomes and multi-cluster risk modelling in Eswatini

BACKGROUND

Halving snakebite morbidity and mortality by 2030 requires countries to develop both prevention and treatment strategies. The paucity of data on the global incidence and severity of snakebite envenoming causes challenges in prioritizing and mobilising resources for snakebite prevention and treatment. In line with the World Health Organisation's 2019 Snakebite Strategy, this study sought to investigate Eswatini's snakebite epidemiology and outcomes, and identify the socio-geographical factors associated with snakebite risk.

METHODOLOGY

Programmatic data from the Ministry of Health, Government of Eswatini 2019-2021, was used to assess the epidemiology and outcomes of snakebite in Eswatini. We developed a snake species richness map from the occurrence data of all venomous snakes of medical importance in Eswatini that was subjected to niche modelling. We formulated four risk indices using snake species richness, various geospatial datasets and reported snakebites. A multivariate cluster modelling approach using these indices was developed to estimate risk of snakebite and the outcomes of snakebite in Eswatini.

PRINCIPAL FINDINGS

An average of 466 snakebites was recorded annually in Eswatini. Bites were recorded across the entire country and peaked in the evening during summer months. Two cluster risk maps indicated areas of the country with a high probability of snakebite and a high probability of poor snakebite outcomes. The areas with the highest rate of snakebite risk were primarily in the rural and agricultural regions of the country.

SIGNIFICANCE

These models can be used to inform better snakebite prevention and treatment measures to enable Eswatini to meet the global goal of reducing snakebite morbidity and mortality by 50% by 2030. The supply chain challenges of antivenom affecting southern Africa and the high rates of snakebite identified in our study highlight the need for improved snakebite prevention and treatment tools that can be employed by health care workers stationed at rural, community clinics.

Compliance with national snakebite treatment guidelines in rural Sri Lankan hospitals: a cluster randomized controlled trial of a brief educational intervention

BACKGROUND

Snakebite is a global health problem that predominantly occurs in rural areas. In Sri Lanka, the majority of snakebite patients first present to smaller rural primary hospitals. Improving care delivered at rural hospitals has the potential to reduce morbidity and mortality from snakebites.

OBJECTIVE

In this study, we evaluated whether an educational intervention would increase compliance with national snakebite treatment guidelines in primary hospitals.

METHODS

The hospitals were randomized into educational intervention (n = 24) and control groups (n = 20). The intervention hospitals received a brief educational intervention based on Sri Lankan Medical Association (SLMA) guidelines on the management of snakebites. Control hospitals had free access to the guidelines but no additional promotion. Four outcomes were assessed: pre- and post-test knowledge at the completion of a one-day workshop of educational intervention (intervention group only); improvement in the quality of the patient's medical records; appropriateness of transfers to higher hospitals; and quality of overall management graded by a blinded expert. The data was collected over a period of 12 months.

RESULTS

All case notes of snakebite hospital admissions were reviewed. There were 1021 cases in the intervention group hospitals and 1165 cases in the control hospitals. Four hospitals in the intervention group and three hospitals in the control group did not have snakebite admissions and were excluded from the cluster analysis. The absolute quality of care was high in both groups. Post-test knowledge was improved (p < 0.0001) following the intervention group's educational workshop. There was no statistical difference between the two groups in terms of clinical data documentation in hospital notes (scores, p = 0.58) or transfer appropriateness (p = 0.68)-both of which were significantly different from the guidelines.

CONCLUSION

Education of primary hospital staff improved the immediate knowledge gained but did not improve record-keeping or the appropriateness of inter-hospital patient transfer.

TRIAL REGISTRATION

The study was registered with Sri Lanka Medical Associations' clinical trial registry. Reg. No SLCTR -2013-023. Registered: 30/07/2013.

Evaluation of the properties of Bungarus caeruleus venom and checking the efficacy of antivenom used in Bangladesh for its bite treatment

As a disaster-prone country with unique geographical features, snake biting is a major public health concern in Bangladesh. The primary reasons of mortality from snakebite include late presentation to the hospital, low efficacy of antivenom, and a lack of adequate management facilities. Because snake venom characteristics vary depending on geographical location, antivenom should be manufactured from snakes native to the region in which it would be administered. Bungarus caeruleus is a highly venomous snake contributing to the major snakebite issue in Bangladesh. Therefore, the neutralization efficacy of the antivenom against B. caeruleus venom was evaluated in the current study along with the characterization of venom. For biological characterization of venom, RP-HPLC and SDS-PAGE profiling, hemolytic activity, hemorrhagic activity, phospholipases A₂ (PLA₂) activity, edema inducing activity and histopathological observations were carried out following standard protocol. LD₅₀ of the venom was calculated along with neutralization potency of Incepta antivenom through probit analysis. Results showed that venom possesses phospholipase A₂ activity, hemolytic activity and edema inducing activity while hemorrhagic activity was absent in the skin of envenomed mice. Histopathological alterations including necrosis, congestion and infiltrations were observed in envenomed mice organs after hematoxylin and eosin staining. Neutralization study showed that Incepta polyvalent antivenom could neutralize (potency 0.53 mg/ml) the lethal effect in in vitro study on mice. Further investigation on snakebite epidemiology and clinical observations of the envenomed patients will help in combating the snakebite problem more efficiently.

Clinico-epidemiology and management of hump-nosed pit viper (Hypnale spp.) bites in dogs

Human envenoming from the bite of the abundant hump-nosed pit viper (Hypnale spp.) (HNPV) is a frequent occurrence with victims experiencing unpleasant and sometimes life-threatening consequences. Further, clinico-pathology, treatment and management measures in HNPV envenomed dogs are under recognized. Prospective investigations were performed to assess the clinico-pathology and management options for HNPV envenomed dogs brought to the University of Peradeniya’s Veterinary Teaching Hospital from January, 2012 to March 2018. We recorded the local and systemic manifestations, hematological and urinary abnormalities of 78 dogs in which HNPV bite had been witnessed by the owner. Mild swelling, extensive swelling, hemorrhagic blistering and hemorrhagic bullae at the site of bite were observed in 59%, 31%, 6% and 4% of the dogs, respectively. Some dogs were subjected to surgical excision of necrotized tissue including limb amputation. We observed the following systemic clinical effects in envenomed dogs: neurotoxicity (13%), acute kidney injury (AKI) (14%) and coagulopathy (16%). All dogs showed leukocytosis with mean white blood cell count of 25.25 × 10³/µL. Mild anemia and thrombocytopenia were detected in 29% of the dogs. There was a significant correlation between extent of local tissue injuries with length of hospitalization (LH). The mean time of coagulopathy observed was 21.3 h (IQR: 8–48 h). In coagulopathic dogs, there was a strong correlation between LH and extent of local tissue injury (r_s = 0.7751, P < 0.0001); LH and whole blood clotting time(CT) (rs = 1.0, P < 0.0001); PT and aPTT (r_s = 0.4712, P < 0.001). LH was significantly correlated with the development of AKI (p = 0.0013). Lack of specific antivenom (AVS) for HNPV envenoming provided an opportunity to study the remaining treatment options. Therefore, the study allowed the identification of local and systemic effects, hematological abnormalities, possible supportive treatments and drawbacks of management measures for envenomed dogs.

A comparative cross-reactivity and paraspecific neutralization study on Hypnale hypnale, Echis carinatus, and Daboia russelii monovalent and therapeutic polyvalent anti-venoms

Envenoming by the hump-nosed pit viper (Hypnale hypnale) raises concern as it inflicts significant debilitation and death in the Western Ghats of India and in the adjacent island nation of Sri Lanka. In India, its medical significance was realized only during 2007 due to its misidentification as Echis carinatus and sometimes as Daboia russelii. Of late, several case reports have underlined the ineptness of the existing polyvalent anti-venom therapy against H. hypnale envenoming. Currently, H. hypnale bite has remained dreadful in India due to the lack of neutralizing anti-venom therapy. Hence, this study was undertaken to establish a systematic comparative, biochemical, pathological, and immunological properties of Sri Lankan H. hypnale venom alongside Indian E. carinatus, and D. russelii venoms. All three venoms differed markedly in the extent of biochemical activities including proteolytic, deoxyribonuclease, L-amino acid oxidase, 5'-nucleotidase, hyaluronidase, and indirect hemolytic activities. The venoms also differed markedly in their pathological properties such as edema, hemorrhage, myotoxic, cardiotoxic, and coagulant activities. The venoms showed stark differences in their protein banding pattern. Strikingly, the affinity-purified rabbit monovalent anti-venoms prepared against H. hypnale, E. carinatus, and D. russelii venoms readily reacted and neutralized the biochemical and pathological properties of their respective venoms, but they insignificantly cross-reacted with, and thus failed to show paraspecific neutralization of any of the effects of the other two venoms, demonstrating the large degree of variations between these venoms. Further, the Indian therapeutic polyvalent anti-venoms from VINS Bioproducts, and Bharath Serums and Vaccines failed to protect H. hypnale venom-induced lethal effects in mice.

Evaluation of a Treatment Algorithm for Tsushima Mamushi (Gloydius tsushimaensis) Snakebites, after Its Introduction to Tsushima Island, Nagasaki, Japan

Objective Tsushima mamushi (Gloydius tsushimaensis) is an endemic species of snake inhabiting only Tsushima Island, a remote Japanese island. We conducted a multicenter, retrospective study of G. tsushimaensis bites for the first time and developed a treatment algorithm that unified treatment on the island and is still in use today. Methods This is a multicenter, retrospective study comparing 72 cases from January 2005 to December 2018, before the introduction of the algorithm, and 12 cases from January 2019 to December 2020, after its introduction. Results There was no significant decrease in the maximum grade of symptoms after the introduction of the algorithm, but there was a decreasing trend (p=0.057). Conversely, the median of the maximum creatinine kinase levels was 343.5 IU/L (interquartile range: 115.5-4,745.5) before the algorithm's introduction and significantly lower (142.5; interquartile range: 111.3-163) after the algorithm's introduction (p=0.042). After the algorithm's introduction, the disseminated intravascular coagulation merger rate and the acute kidney injury incidence both dropped to 0%, from 9.7% and 6.9%, respectively, before the algorithm's introduction. There was no significant difference in the length of hospital stay before versus after the algorithm's introduction. Conclusion This study showed that the treatment algorithm can be safely and quickly applied. The algorithm's effectiveness is expected to be strengthened by the accumulation of more cases in the future.

Assessment of quality and pre-clinical efficacy of a newly developed polyvalent antivenom against the medically important snakes of Sri Lanka

Snake envenomation is a severe problem in Sri Lanka (SL) and Indian polyvalent antivenom (PAV) is mostly used for treating snakebite albeit due to geographical variation in venom composition, Indian PAV shows poor efficacy in neutralizing the lethality and toxicity of venom from the same species of snakes in SL. Therefore, the quality and in vivo venom neutralization potency of a country-specific PAV produced against the venom of the five most medically important snakes of SL (Daboia russelii, Echis carinatus, Hypnale hypnale, Naja naja, Bungarus caeruleus) was assessed. LC-MS/MS analysis of two batches of PAV showed the presence of 88.7-97.2% IgG and traces of other plasma proteins. The tested PAVs contained minor amounts of undigested IgG and F(ab')2 aggregates, showed complement activation, were devoid of IgE, endotoxin, and content of preservative was below the threshold level. Immunological cross-reactivity and in vitro neutralization of enzymatic activities, pharmacological properties demonstrated superior efficacy of SL PAV compared to Indian PAV against SL snake venoms. The in vivo neutralization study showed that the tested PAVs are potent to neutralize the lethality and venom-induced toxicity of SL snake venoms. Therefore, our study suggests that introduction of SL-specific PAV will improve snakebite management in SL.

Addressing the global snakebite crisis with geo-spatial analyses - Recent advances and future direction

Venomous snakebite is a neglected tropical disease that annually leads to hundreds of thousands of deaths or long-term physical and mental ailments across the developing world. Insufficient data on spatial variation in snakebite risk, incidence, human vulnerability, and accessibility of medical treatment contribute substantially to ineffective on-ground management. There is an urgent need to collect data, fill knowledge gaps and address on-ground management problems. The use of novel, and transdisciplinary approaches that take advantage of recent advances in spatio-temporal models, 'big data', high performance computing, and fine-scale spatial information can add value to snakebite management by strategically improving our understanding and mitigation capacity of snakebite. We review the background and recent advances on the topic of snakebite related geospatial analyses and suggest avenues for priority research that will have practical on-ground applications for snakebite management and mitigation. These include streamlined, targeted data collection on snake distributions, snakebites, envenomings, venom composition, health infrastructure, and antivenom accessibility along with fine-scale models of spatio-temporal variation in snakebite risk and incidence, intraspecific venom variation, and environmental change modifying human exposure. These measures could improve and 'future-proof' antivenom production methods, antivenom distribution and stockpiling systems, and human-wildlife conflict management practices, while simultaneously feeding into research on venom evolution, snake taxonomy, ecology, biogeography, and conservation.

Prevention and improvement of clinical management of snakebite in Southern Asian countries: A proposed road map

In the Southern Asian countries, snakebite takes a substantial toll in terms of human life, inflicts acute morbidity and long term disability both physical and psychological, and therefore represents a neglected socio-economic problem and severe health issue that requires immediate medical attention. The 'Big Four' venomous snakes, viz. Daboia russelii, Naja naja, Bungarus caeruleus and Echis carinatus, are prominent, medically important species and are the most dangerous snakes of this region; therefore, the commercial polyvalent antivenom (PAV) contains antibodies against the venoms of these snakes. However, envenomations by species other than the 'Big Four' snakes are grossly neglected, and PAV is only partially effective in neutralizing the venom of these snakes. Many issues confounding effective treatment of snakebite are discussed in this review, and these hurdles preventing successful treatment of snakebite must be addressed. However, in South Asian countries, the pre-hospital treatment and appropriate first aid are equally important to mitigate the problem of snakebite and therefore, these issues are also highlighted here. Further, this review suggests a roadmap and guidelines for the prevention of snakebite and improvement of hospital management of snakebite in these Southern Asian countries.

Elucidating the Venom Diversity in Sri Lankan Spectacled Cobra (Naja naja) through De Novo Venom Gland Transcriptomics, Venom Proteomics and Toxicity Neutralization

Inadequate effectiveness of Indian antivenoms in treating envenomation caused by the Spectacled Cobra/Indian Cobra (Naja naja) in Sri Lanka has been attributed to geographical variations in the venom composition. This study investigated the de novo venom-gland transcriptomics and venom proteomics of the Sri Lankan N. naja (NN-SL) to elucidate its toxin gene diversity and venom variability. The neutralization efficacy of a commonly used Indian antivenom product in Sri Lanka was examined against the lethality induced by NN-SL venom in mice. The transcriptomic study revealed high expression of 22 toxin genes families in NN-SL, constituting 46.55% of total transcript abundance. Three-finger toxins (3FTX) were the most diversely and abundantly expressed (87.54% of toxin gene expression), consistent with the dominance of 3FTX in the venom proteome (72.19% of total venom proteins). The 3FTX were predominantly S-type cytotoxins/cardiotoxins (CTX) and α-neurotoxins of long-chain or short-chain subtypes (α-NTX). CTX and α-NTX are implicated in local tissue necrosis and fatal neuromuscular paralysis, respectively, in envenomation caused by NN-SL. Intra-species variations in the toxin gene sequences and expression levels were apparent between NN-SL and other geographical specimens of N. naja, suggesting potential antigenic diversity that impacts antivenom effectiveness. This was demonstrated by limited potency (0.74 mg venom/ml antivenom) of the Indian polyvalent antivenom (VPAV) in neutralizing the NN-SL venom. A pan-regional antivenom with improved efficacy to treat N. naja envenomation is needed.

Adjunct treatment in snakebite envenoming: a systematic review of randomised controlled trials

Adjunct therapy in snakebite may be lifesaving if administered appropriately or can be harmful if non-judicious use leads to avoidable delays in administering antivenom. This systematic review analyses the evidence from randomised controlled trials (RCTs) on the efficacy of adjunct treatment administered with antivenom. PubMed, EMBASE, Scopus, Cochrane library and CINAHL were searched for RCTs enrolling patients with snakebite envenoming where a treatment other than antivenom has been assessed for its efficacy within the last 25 y. Fifteen studies met the inclusion criteria. The interventions assessed were categorised as adjunct therapies (heparin or fresh frozen plasma) to reverse haemotoxicity (three studies), antibiotics to prevent local infections (three studies), steroids to reduce local swelling (one study), premedication (adrenaline, steroids and antihistamines, either alone or in combination) to reduce hypersensitivity reactions to antivenom (five studies) and other interventions (three studies). Apart from a beneficial effect of low-dose adrenaline (1:1000, 0.25 ml administered subcutaneously) in preventing antivenom-induced hypersensitivities (OR: 0.54, 95% CI 0.32 to 0.93, two RCTs, 354 participants, moderate certainty evidence) in Sri Lanka, evidence for any other adjunct therapy is either non-existent or needs confirmation by larger better designed trials.

The application of laboratory-based analytical tools and techniques for the quality assessment and improvement of commercial antivenoms used in the treatment of snakebite envenomation

Snakebite envenomation is a public health problem of high impact, particularly for the developing world. Antivenom, which contains whole or protease-digested immunoglobulin G, purified from the plasma of hyper-immunized animals (mainly horses), is the mainstay for the treatment of snakebite envenomation. The success of antivenom therapy depends upon its ability to abrogate or reduce the local and systemic toxicity of envenomation. In addition, antivenom administration must be safe for the patients. Therefore, antivenom manufacturers must ensure that these products are effective and safe in the treatment of envenomations. Antivenom efficacy and safety are determined by the physicochemical characteristics of formulations, purity of the immunoglobulin fragments and antibodies, presence of protein aggregates, endotoxin burden, preservative load, and batch to batch variation, as well as on the ability to neutralize the most important toxins of the venoms against which the antivenom is designed. In this context, recent studies have shown that laboratory-based simple analytical techniques, for example, size exclusion chromatography, sodium dodecyl sulphate polyacrylamide gel electrophoresis, mass spectrometry, immunological profiling including immuno-turbidimetry and enzyme-linked immunosorbent assays, Western blotting, immune-chromatographic technique coupled to mass spectrometry analysis, reverse-phase high performance liquid chromatography, spectrofluorometric analysis, in vitro neutralization of venom enzymatic activities, and other methodologies, can be applied for the assessment of antivenom quality, safety, stability, and efficacy. This article reviews the usefulness of different analytical techniques for the quality assessment of commercial antivenoms. It is suggested that these tests should be applied for screening the quality of commercial antivenoms before their preclinical and clinical assessment.

Overview of snakebite in Brazil: Possible drivers and a tool for risk mapping

Snakebite envenoming affects close to 2.7 million people globally every year. In Brazil, snakebites are reported to the Ministry of Health surveillance system and cases receive antivenom free of charge. There is an urgent need to identify higher risk areas for antivenom distribution, and to develop prevention activities. The objective of this study is to provide an overview of the epidemiological situation of snakebite envenoming in Brazil and explore possible drivers; as well as to create a flowchart tool to support decision-makers identify higher risk areas. An ecological-type study was carried out using data by municipality (2013–2017). Study parts: 1) Create a geocoded database and perform a descriptive and cluster analysis; 2) Statistical analysis to measure the association of snakebite and possible environmental and socioeconomic drivers; 3) Develop a flowchart to support decision-makers and the application of this tool in one state (Rio Grande do Sul) as an example. An average of 27,120 snakebite cases per year were reported at the country level. Clusters of municipalities with high numbers of snakebites are mostly found in the Amazon Legal Region. The negative binomial regression model showed association with the snakebite case count: the type of major habitat, tropical or non-tropical; temperature; percentage of urbanization; precipitation; elevation; GDP per capita; a weaker relation with forest loss; and with venomous snake richness. The state where the instrument was applied reported 4,227 snakebites in the period. Most municipalities were considered as medium risk and 56/496 as high risk according to the tool created. Snakebite cases are distributed across the entire country with the highest concentration in the Legal Amazon Region. This creates a complex situation both for better understanding of the association of environmental and socioeconomic factors with snakebites and for the distribution and maintenance of antivenom to remote areas. Research into types of antivenom with a longer shelf life without the need for refrigeration is needed.

It is estimated that snakebite envenoming affects around 2.7 million people every year worldwide. In Brazil, snakebite is part of the Ministry of Health surveillance system and cases receive antivenom free of charge. With a vast territory and limited production of antivenom, there is need to identify higher risk areas for its distribution and to develop preventative actions. The objective of this study is to provide an overview of the epidemiological situation of snakebite envenoming in Brazil and explore possible environmental and socioeconomic factors related to snakebites. On the basis of this information, a flowchart tool to support decision-makers identify higher risk areas was created and applied in one state as an example. An average of 27,120 snakebite cases per year were reported in Brazil, with the highest number of cases and rates in the Legal Amazon Region. The multivariable statistics analysis showed association of snakebite with environmental factors (type of major habitat, tropical or non-tropical; temperature; precipitation; elevation) and socioeconomic (lower percentage of urbanization; lower GDP per capita); also, a weaker relation with forest loss, and with venomous snake richness. The tool created to support decision-makers was applied in the state of Rio Grande do Sul, with 4,227 reported snakebites during the period. According to this tool, the majority of municipalities in this state were considered as medium risk and 56/496 as high risk. Snakebite cases are distributed across the entire country; however, the highest concentration is in the Legal Amazon Region. This creates a complex situation both for better understanding of the association of environmental and socioeconomic factors with snakebites and for the distribution and maintenance of antivenom to remote areas.

Prevalence, vulnerability and epidemiological characteristics of snakebite in agricultural settings in rural Sri Lanka: A population-based study from South Asia

Background

The burden of snakebite remains poorly characterised because of the paucity of population-based data. Further, factors determining the vulnerability of individuals within rural communities to snakebite have been rarely investigated. We undertook a population-based study to determine the prevalence, vulnerability and epidemiological characteristics of snakebite in rural Sri Lanka.

Methods and findings

A population-based cross-sectional study was conducted among 8707 current residents in the district of Ampara, representing typical rural Sri Lanka. The sample was recruited using multi-stage cluster sampling with probability proportionate-to-size. Snakebite victims were identified using the WHO criteria. Data were collected using a pre-tested interviewer-administered questionnaire.

Each household had on average 3.8 persons; mean age 28.3 years (SD = 18.2); 51.3% males. The one-year point prevalence of snakebites was 17.6 per 1000 residents (95% CI: 15–20.6) and 6.12 per 100 households (95% CI: 5.25–7.13), while the lifetime prevalence was 9.4 per 100 residents (95% CI: 8.8–10.0) and 30.5 per 100 households (95% CI: 28.6–32.2) with a case fatality ratio of 0.033. Venomous snakebites accounted for 28.1%; snakes were unidentified among 30.1%. Compared to the non-snakebite victims, being single, males, of Sinhala ethnicity, aged >19 years, low education and socioeconomic status, engaging in farming or unskilled outdoor occupations denoted vulnerability to snakebites. Outdoor bites (77.8%) were more common among males; during daytime; mostly while walking; within the rural terrains and home gardens; on lower limbs; mostly by hump-nosed and Russell viper. Indoor bites were more common among females; during night-time; while sleeping and barefooted; on lower limbs; mostly by hump-nosed vipers, kraits and non-venomous snakes.

Conclusions

The burden of snakebite is considerably high among rural populations. The concept of vulnerability can be useful in healthcare decision-making and resource allocation.

The Failures of Ethnobotany and Phytomedicine in Delivering Novel Treatments for Snakebite Envenomation

Snakebite envenomation (SBE) is a high-priority, neglected tropical disease. This devastating occupational health hazard disproportionately affects rural farming communities in tropical countries. This is exacerbated by the distribution and densities of venomous snakes, incidence of encounters, and limited access to advanced healthcare, including antivenom. Before the development of antivenom, desperation and spiritual beliefs led patients to experiment with a wide range of traditional treatments. Many of these treatments still survive today, particularly in regions where access to healthcare is limited. Plants are a major source of bioactive molecules, including several lifesaving medications that are widely used to this day. However, much of the research into the use of traditional plant treatments for SBE are limited to preliminary analysis or have focused on techniques used to confirm antibody efficacy that are not suitable for non-antibody-containing treatments. Modern drugs are developed through a robust pharmaceutical drug discovery and development process, which applies as much to SBE as it does to any other disease. This review discusses specifically why research into ethnobotanical practices has failed to identify or develop a novel treatment for SBE and proposes specific approaches that should be considered in this area of research in the future.

Time delays in treatment of snakebite patients in rural Sri Lanka and the need for rapid diagnostic tests

Delays in treatment seeking and antivenom administration remain problematic for snake envenoming. We aimed to describe the treatment seeking pattern and delays in admission to hospital and administration of antivenom in a cohort of authenticated snakebite patients. Adults (> 16 years), who presented with a confirmed snakebite from August 2013 to October 2014 were recruited from Anuradhapura Hospital. Demographic data, information on the circumstances of the bite, first aid, health-seeking behaviour, hospital admission, clinical features, outcomes and antivenom treatment were documented prospectively. There were 742 snakebite patients [median age: 40 years (IQR:27–51; males: 476 (64%)]. One hundred and five (14%) patients intentionally delayed treatment by a median of 45min (IQR:20-120min). Antivenom was administered a median of 230min (IQR:180–360min) post-bite, which didn’t differ between directly admitted and transferred patients; 21 (8%) receiving antivenom within 2h and 141 (55%) within 4h of the bite. However, transferred patients received antivenom sooner after admission to Anuradhapura hospital than those directly admitted (60min [IQR:30-120min] versus 120min [IQR:52-265min; p<0.0001]). A significantly greater proportion of transferred patients had features of systemic envenoming on admission compared to those directly admitted (166/212 [78%] versus 5/43 [12%]; p<0.0001), and had positive clotting tests on admission (123/212 [58%] versus 10/43 [23%]; p<0.0001). Sri Lankan snakebite patients present early to hospital, but there remains a delay until antivenom administration. This delay reflects a delay in the appearance of observable or measurable features of envenoming and a lack of reliable early diagnostic tests. Improved early antivenom treatment will require reliable, rapid diagnostics for systemic envenoming.

Snakebite is a neglected tropical disease which is closely associated with underdevelopment. Poor accessibility to safe and effective antivenoms is a major issue in some regions highest-affected by snakebites. Antivenom can prevent severe effects of envenoming if given early. Therefore, educating communities and health care workers to improve treatment seeking after snakebite is a global priority. Many factors are associated with delayed presentation to hospital and early administration of antivenom. We found that most snakebite patients in Sri Lanka present to the first hospital within an hour of the bite. However, there remains a delay of about two more hours until the first dose of antivenom is administered. This delay is a reflection of a delay in the appearance of observable or measurable features of envenoming and a lack of reliable early diagnostic tests. We emphasise the need for reliable, rapid diagnostics for systemic envenoming.

Development of a Treatment Protocol for Cobra (Naja naja) Bite Envenoming in Dogs

There is limited information on clinical profiles, treatment, and management aspects of Indian cobra (Naja naja) bite envenoming in dogs in Sri Lanka. Dogs with cobra bites presented to the Veterinary Teaching Hospital (VTH), University of Peradeniya, were prospectively studied over a period of 72 months; local and systemic clinical manifestations and hematological abnormalities were recorded. We studied 116 cobra bite envenomings in dogs. A grading system was established using a combination of anatomical site of fang marks, as well as local and systemic clinical manifestations. Accordingly, treatment strategies were established using Indian polyvalent antivenom (AVS). Pain and swelling at the bite site were major clinical signs observed, while neurotoxic manifestations (mydriasis, wheezing, and crackles) were detected in most dogs. Leukocytosis was observed in 78% of them. Statistical analysis revealed that the grading scores obtained were compatible to initiate AVS administration according to the severity. The minimum number required was 2 AVS vials (range 2-12). Almost 20% of the dogs developed wheezing, crackles, hypersalivation, restlessness, and dyspnea as adverse reactions to AVS treatment. Necrotic wounds on bitten anatomical sites developed in 19% of the dogs and 2.5% developed acute kidney injuries as a consequence of envenoming crisis. Despite treatment, 3% of dogs died. No dry bites were recorded.

Phylovenomics of Daboia russelii across the Indian subcontinent. Bioactivities and comparative in vivo neutralization and in vitro third-generation antivenomics of antivenoms against venoms from India, Bangladesh and Sri Lanka

Russell's viper (Daboia russelii) is, together with Naja naja, Bungarus caeruleus and Echis carinatus, a member of the medically important 'Big Four' species responsible for causing a large number of morbidity and mortality cases across the Indian subcontinent. Despite the wide distribution of Russell's viper and the well-documented ubiquity of the phenomenon of geographic variability of intraspecific snake venom composition, Indian polyvalent antivenoms against the "Big Four" venoms are raised against venoms sourced mainly from Chennai in the southeastern Indian state of Tamil Nadu. Biochemical and venomics investigations have consistently revealed notable compositional, functional, and immunological differences among geographic variants of Russell's viper venoms across the Indian subcontinent. However, these studies, carried out by different laboratories using different protocols and involving venoms from a single geographical region, make the comparison of the different venoms difficult. To bridge this gap, we have conducted bioactivities and proteomic analyses of D. russelii venoms from the three corners of the Indian subcontinent, Pakistan, Bangladesh, and Tamil Nandu (India) and Sri Lanka, along with comparative in vivo neutralization and in vitro third-generation antivenomics of antivenoms used in India, Bangladesh and Sri Lanka. These analyses let us to propose two alternative routes of radiation for Russell's viper in the Indian subcontinent. Both radiations, towards the northeast of India and Bangladesh and towards south India and Sri Lanka, have a common origin in Pakistan, and provide a phylovenomics ground for rationalizing the geographic variability in venom composition and their distinct immunoreactivity against available antivenoms. BIOLOGICAL SIGNIFICANCE: Russell's viper (Daboia russelii), the Indian cobra (Naja naja), the common krait (Bungarus caeruleus), and the saw-scaled viper (Echis carinatus) constitute the 'Big Four' snake species responsible for most snakebite envenomings and deaths in the Indian subcontinent. Despite the medical relevance of Daboia russelii, and the well documented variations in the clinical manifestations of envenomings by this wide distributed species, which are doubtless functionally related to differences in venom composition of its geographic variants, antivenoms for the clinical treatment of envenomings by D. russelii across the Indian subcontinent are invariably raised using venom sourced mainly from the southeastern Indian state of Tamil Nadu. We have applied a phylovenomics approach to compare the venom proteomes of Russell's vipers from the three corners of the Indian subcontinent, Pakistan, Bangladesh, and South India/Sri Lanka, and have assessed the in vitro (third-generation antivenomics) and in vivo preclinical efficacy of a panel of homologous antivenoms. The identification of two dispersal routes of ancestral D. russelii into the Indian subcontinent provides the ground for rationalizing the variability in composition and immunoreactivity of the venoms of extant geographic variants of Russell's viper. Such knowledge is relevant for envisioning strategies to improve the clinical coverage of anti- D. russelii antivenoms.

Clinico-epidemiology and management of Russell's viper (Daboia russelii) envenoming in dogs in Sri Lanka

INTRODUCTION

Russell's viper envenoming in dogs is a significant problem in Sri Lanka. The current study focused on investigating clinical profile, laboratory findings of three selected tests and to develop a treatment strategy with Indian polyvalent Anti-Venom Serum (AVS). It was also intended to report adverse effects and complications caused by both Russell's viper venom (RVV) and AVS in Russell's Viper (RV) envenomed dogs.

OBJECTIVE

To evaluate and report the clinical manifestations, to find out the minimum effective vials of AVS and to record AVS induced adverse reactions of RV envenoming in dogs.

MATERIALS AND METHODS

A prospective study was conducted on Russell's viper bitten dogs (n = 65) admitted to the Veterinary Teaching Hospital (VTH) in Sri Lanka. Indian polyvalent AVS was used to treat all the envenomed dogs. The number of vials of AVS that was administered to a patient was decided upon by a second degree polynomial model with a number of vials of AVS in the X axis verses Prothrombine Time (PT), Activated Partial Thromboplastine Time (aPTT) and Clotting Time (CT) in the Y axis respectively.

RESULTS

Varying degrees of pain were exhibited by all the victim dogs. Mild swelling and necrosis at the site of bite was seen in 54% (n = 35) and 37% (n = 24) of dogs respectively. Prolonged values of, PT, aPTT and CT were seen from all the RV envenomed dogs. The mean leukocyte count in these dogs was 39.79 × 103/μL (normal range; 4-20 × 103/μL) (IQR:29.05 × 103/μL-45.92 × 103/μL). Statistical analysis showed that the initial vials of 7 AVS would be the minimum required vials. Therefore, a range of 6-15 AVS vials in total were administered to these dogs and in 7.6% (n = 5) of dogs, the results of PT, aPTT and CT became normal with 6 AVS vials at 32-97 minutes. Acute Renal Failure (ARF) was detected from 29% (n = 19) of dogs as a complication.

CONCLUSIONS

Systemic clinical signs of haemorrhagic lesions, cardio respiratory toxicities were common in Russell's viper envenomed dogs. Initially 6 vials of AVS must be administered. AVS induced reactions were reported commonly. Russell's viper envenoming was found to be lethal in dogs.

Nephrotoxicity induced by the venom of Hypnale hypnale from Sri Lanka: Studies on isolated perfused rat kidney and renal tubular cell lines

The hump-nosed pit viper Hypnale hypnale is responsible for a high number of snakebite cases in southwestern India and Sri Lanka. Although most patients only develop local signs and symptoms of envenoming, there is a growing body of evidence indicating that these envenomings may be associated with systemic alterations, including acute kidney injury. In this study we evaluated the renal toxicity of H. hypnale venom by using a perfused isolated rat kidney system and by assessing cytotoxicity in two different renal tubular cell lines in culture. The venom caused alterations in several renal functional parameters, such as reduction on perfusion pressure, renal vascular resistance, and sodium and chloride tubular transport, whereas glomerular filtration rate and urinary flow initially decreased and then increased after venom perfusion. In addition, this venom was cytotoxic to proximal and distal renal tubular cells in culture, with predominance of necrosis over apoptosis. Moreover, the venom affected the mitochondrial membrane potential and induced an increment in reactive oxygen species in these cells. Taken together, our results demonstrate a nephrotoxic activity of H. hypnale venom in these experimental models, in agreement with clinical observations.

Evaluating temporal patterns of snakebite in Sri Lanka: the potential for higher snakebite burdens with climate change

Background

Snakebite is a neglected tropical disease that has been overlooked by healthcare decision makers in many countries. Previous studies have reported seasonal variation in hospital admission rates due to snakebites in endemic countries including Sri Lanka, but seasonal patterns have not been investigated in detail.

Methods

A national community-based survey was conducted during the period of August 2012 to June 2013. The survey used a multistage cluster design, sampled 165 665 individuals living in 44 136 households and recorded all recalled snakebite events that had occurred during the preceding year. Log-linear models were fitted to describe the expected number of snakebites occurring in each month, taking into account seasonal trends and weather conditions, and addressing the effects of variation in survey effort during the study and of recall bias amongst survey respondents.

Results

Snakebite events showed a clear seasonal variation. Typically, snakebite incidence is highest during November-December followed by March-May and August, but this can vary between years due to variations in relative humidity, which is also a risk factor. Low relative-humidity levels are associated with high snakebite incidence. If current climate-change projections are correct, this could lead to an increase in the annual snakebite burden of 31.3% (95% confidence interval: 10.7-55.7) during the next 25-50 years.

Conclusions

Snakebite in Sri Lanka shows seasonal variation. Additionally, more snakebites can be expected during periods of lower-than-expected humidity. Global climate change is likely to increase the incidence of snakebite in Sri Lanka.

The Venom of Spectacled Cobra (Elapidae: Naja naja): In Vitro Study from Distinct Geographical Origins in Sri Lanka

Several countries residing envenomation due to Naja naja had revealed a disparity in the venom composition according to their geographic location and Sri Lankan cobra still lacks the evidence to support this. Therefore, the current study was focused on addressing relationship between the histopathological changes according to geographic variation of Sri Lankan N. naja venom. The histopathological changes in vital organs and muscle tissues following intramuscular administration of venom of N. naja were studied using BALB/c mice. The median lethal dose of venom of N. naja in the present study was determined to be 0.55, 0.66, 0.68, 0.62, and 0.7 mg/kg for North (NRP), Central (CRP), Western, Southern, and Sabaragamuwa Regional Population venoms, respectively. Histopathological changes were observed in different levels in vital organs and muscle tissues of mice. NRP accompanied significantly higher infiltration of inflammatory and necrotic cells into skeletal muscle and CRP venom demonstrated high level of cardiotoxic effects comparing to other regions. This study revealed a certain extent of variations in the pathological effects of N. naja venom samples according to their geographical distribution.

Health seeking behavior following snakebites in Sri Lanka: Results of an island wide community based survey

INTRODUCTION

Sri Lanka has a population of 21 million and about 80,000 snakebites occur annually. However, there are limited data on health seeking behavior following bites. We investigated the effects of snakebite and envenoming on health seeking behavior in Sri Lanka.

METHODS

In a community-based island-wide survey conducted in Sri Lanka 44,136 households were sampled using a multistage cluster sampling method. An individual who reported experiencing a snakebite within the preceding 12 months was considered a case. An interviewer-administered questionnaire was used to obtain details of the bite and health seeking behavior among cases.

RESULTS

Among 165,665 individuals surveyed, there were 695 snakebite victims. 682 (98.1%) had sought health care after the bite; 381 (54.8%) sought allopathic treatment and 301 (43.3%) sought traditional treatment. 323 (46.5%) had evidence of probable envenoming, among them 227 (70.3%) sought allopathic treatment, 94 (29.1%) sought traditional treatment and 2 did not seek treatment. There was wide geographic variation in the proportion of seeking allopathic treatment from <20% in the Western province to > 90% in the Northern province. Multiple logistic regression analysis showed that seeking allopathic treatment was independently associated with being systemically envenomed (Odds Ratio = 1.99, 95% CI: 1.36-2.90, P < 0.001), distance to the healthcare facility (OR = 1.13 per kilometer, 95% CI: 1.09 to 1.17, P < 0.001), time duration from the bite (OR = 0.49 per day, 95% CI: 0.29-0.74, P = 0.002), and the local incidence of envenoming (OR = 1.31 for each 50 per 100,000, 95% CI: 1.19-1.46, P < 0.001) and snakebite (OR = 0.90 for each 50 per 100,000, 95% CI: 0.85-0.94, P < 0.001) in the relevant geographic area.

CONCLUSIONS

In Sri Lanka, both allopathic and traditional treatments are sought following snakebite. The presence of probable envenoming was a major contribution to seeking allopathic treatment.

Hematological and plasma biochemical parameters in a wild population of Naja naja (Linnaeus, 1758) in Sri Lanka

BACKGROUND

Hematological studies of any animal species comprise an important diagnostic method in veterinary medicine and an essential tool for the conservation of species. In Sri Lanka, this essential technique has been ignored in studies of many species including reptiles. The aim of the present work was to establish a reference range of hematological values and morphological characterization of wild spectacled cobras (Naja naja) in Sri Lanka in order to provide a diagnostic tool in the assessment of health condition in reptiles and to diagnose diseases in wild populations.

METHODS

Blood samples were collected from the ventral caudal vein of 30 wild-caught Naja naja (18 males and 12 females). Hematological analyses were performed using manual standard methods.

RESULTS

Several hematological parameters were examined and their mean values were: red blood cell count 0.581 ± 0.035 × 10⁶/μL in males; 0.4950 ± 0.0408 × 10⁶/μL in females; white blood cell count 12.45 ± 1.32 × 10³/μL in males; 11.98 ± 1.62 × 10³/μL in females; PCV (%) in males was 30.11 ± 1.93 and in females was 23.41 ± 1.67; hemoglobin (g/dL) was 7.6 ± 0.89 in males and 6.62 ± 1.49 in females; plasma protein (g/dL) was 5.11 ± 0.75 in males and 3.25 ± 0.74 in females; whereas cholesterol (mg/mL) was 4.09 ± 0.12 in males and 3.78 ± 0.42 in females. There were no significant differences in hematological parameters between the two genders except for erythrocyte count, thrombocyte count, hematocrit, hemoglobin, plasma protein, percentage of azurophil and heterophil. Intracellular parasites were not found in any of the studied specimens.

CONCLUSION

Hematological and plasma biochemical parameters indicated a difference between geographically isolated populations and some values were significantly different between the two genders. These hematological results provide a reference range for Sri Lankan population of adult Naja naja.

Development of a new polyspecific antivenom for snakebite envenoming in Sri Lanka: Analysis of its preclinical efficacy as compared to a currently available antivenom

A new whole IgG, freeze-dried, polyspecific antivenom was prepared from the plasma of horses immunized with the venoms of the snakes Daboia russelii, Echis carinatus, Hypnale hypnale, and Naja naja from Sri Lanka. The preclinical neutralizing ability of this antivenom against several toxic and enzymatic activities of these four venoms was analyzed, and compared with that of a batch of VINS antivenom (India) being currently used in Sri Lanka. The activities tested were: lethality, hemorrhagic, in vitro coagulant, proteinase and phospholipase A₂. Both antivenoms neutralized, to a different extent, these activities of the venom of D. russelii, E. carinatus, and N. naja. In general, the polyspecific Sri Lankan antivenom was more effective than the Indian antivenom in the neutralization of the venoms of D. russelii and E. carinatus, whereas the Indian antivenom showed a higher efficacy against the venom of N. naja. Regarding H. hypnale, the new Sri Lankan antivenom was effective in the neutralization of all activities tested, whereas the Indian antivenom neutralized lethality but not hemorrhagic, coagulant, proteinase and PLA₂ activities, in agreement with the fact that this venom is not included in the immunization mixture for this antivenom. Results suggest that the new polyspecific Sri Lankan antivenom has a satisfactory preclinical neutralizing profile and compares favorably with the Indian antivenom. This is ready to be tested in a clinical trial to evaluate its efficacy and safety in human victims of snakebite envenomings by D. russelii, E. carinatus and H. hypnale in Sri Lanka.

Multisystem failure and death due to extensive hemorrhaging and brain herniation subsequent to a bite by an unidentified snake

Background

Snakebites cause considerable morbidity and mortality in tropical and subtropical countries even though existing treatment methods can prevent most deaths if presentation occurs early to hospitals. Envenomation by unidentified snakes is common in central Sri Lanka. Management of such patients is challenging especially if presentation is late.

Case presentation

Here, we report a case of a 52-year-old man from central Sri Lanka who presented late after being bitten by an unidentified snake. He developed `severe coagulopathy, neurotoxicity, acute kidney injury, and rhabdomyolysis. Subsequently, despite of treatment, he died due to extensive hemorrhaging in many organs. A large intracranial hemorrhage lead to fatal brain herniation.

Conclusions

Envenomation by some snake species can severely affect multiple body systems and give rise to fatal brain hemorrhages and brain herniation. Considering the known effects of local snake venom, the responsible species is likely to be Russell’s viper (Daboia russelii). We recommend some simple measures to reduce the chances of such deaths in the future.

Understanding and confronting snakebite envenoming: The harvest of cooperation

During 45 years, the Instituto Clodomiro Picado (ICP, University of Costa Rica) has developed an ambitious scientific, technological, productive, and social program aimed at providing a better understanding of snakes and their venoms, contributing to the development, production and distribution of antivenoms, improving the prevention and management of snakebite envenomings, and strengthening human resources in science and technology. Among other topics, its research agenda has focused on the local tissue alterations induced by viperid snake venoms, i.e. myonecrosis, hemorrhage, dermonecrosis, extracellular matrix degradation, lymphatic vessel damage, and inflammation. In addition, the preclinical efficacy of antivenoms has been thoroughly investigated, together with the technological development of novel antivenoms. ICP's project has been based on a philosophical frame characterized by: (a) An integrated approach for confronting the problem of snakebites, involving research, production, extension activities, and teaching; (b) a cooperative and team work perspective in the pursuit of scientific, technological, productive, and social goals; (c) a search for excellence and continuous improvement in the quality of its activities; and (d) a vision of solidarity and compassion, based on the realization that snakebite envenomings mostly affect impoverished vulnerable populations in the rural settings of developing countries. A key aspect in this program has been the consolidation of international partnerships with groups of all continents, within a frame of academic and social cooperation, some of which are described in this review.

Venomics, lethality and neutralization of Naja kaouthia (monocled cobra) venoms from three different geographical regions of Southeast Asia

Previous studies showed that venoms of the monocled cobra, Naja kaouthia from Thailand and Malaysia are substantially different in their median lethal doses. The intraspecific venom variations of N. kaouthia, however, have not been fully elucidated. Here we investigated the venom proteomes of N. kaouthia from Malaysia (NK-M), Thailand (NK-T) and Vietnam (NK-V) through reverse-phase HPLC, SDS-PAGE and tandem mass spectrometry. The venom proteins comprise 13 toxin families, with three-finger toxins being the most abundant (63-77%) and the most varied (11-18 isoforms) among the three populations. NK-T has the highest content of neurotoxins (50%, predominantly long neurotoxins), followed by NK-V (29%, predominantly weak neurotoxins and some short neurotoxins), while NK-M has the least (18%, some weak neurotoxins but less short and long neurotoxins). On the other hand, cytotoxins constitute the main bulk of toxins in NK-M and NK-V venoms (up to 45% each), but less in NK-T venom (27%). The three venoms show different lethal potencies that generally reflect the proteomic findings. Despite the proteomic variations, the use of Thai monovalent and Neuro polyvalent antivenoms for N. kaouthia envenomation in the three regions is appropriate as the different venoms were neutralized by the antivenoms albeit at different degrees of effectiveness.

BIOLOGICAL SIGNIFICANCE

Biogeographical variations were observed in the venom proteome of monocled cobra (Naja kaouthia) from Malaysia, Thailand and Vietnam. The Thai N. kaouthia venom is particularly rich in long neurotoxins, while the Malaysian and Vietnamese specimens were predominated with cytotoxins. The differentially expressed toxin profile accounts for the discrepancy in the lethal dose of the venom from different populations. Commercially available Thai antivenoms (monovalent and polyvalent) were able to neutralize the three venoms at different effective doses, hence supporting their uses in the three regions. While dose adjustment according to geographical region seems possible, changes to standard recommended dosage should only be made if further study validates that the monocled cobras within a population do not exhibit remarkable inter-individual venom variation.

PID15, a novel 6 kDa secreted peptide, mediates Naja naja venom phospholipase A₂ induced apoptosis in isolated human peripheral lymphocytes

Background

Snake venoms are a complex mixture of active principles mainly peptides and proteins also including amino acids, nucleotides, free lipids, carbohydrates and metallic elements bound to proteins that interfere in several biological systems. In this study, we aimed to understand the mode of action of the apoptosis inducing ability of Naja naja venom phospholipase A₂ (NV-PLA₂) using isolated human peripheral lymphocytes.

Results

Human peripheral lymphocytes when incubated with Naja naja venom phospholipase A₂ (NV-PLA₂) induced up to 68% DNA fragmentation. The dialysed conditioned media obtained by incubating lymphocytes with NV-PLA₂ at 15^th min induced 44% DNA fragmentation, referred to as cmlp-active. Cmlp-active showed 20.5% increased protein concentration than the corresponding control condition media cmlp-c-15. Test for creatine kinase activity in cmlp-active proved negative and negligible amount of lactate dehydrogenase did not show significant DNA fragmentation. Fractionation of cmlp-active on Sephadex G-25 showed two peaks, major peak induced 38% DNA fragmentation, which was further rechromatographed on Sephadex G-25. The single peak obtained was named PID15 (Phospholipase A₂Induced DNA fragmentation factor secreted at 15^th min). Q-Tof MS/MS analysis of PID-15 showed it is a 6 kDa peptide. PID15 sequence analysis gave 40 amino acids in the following order, msilpcknvs iwvikdtaas dkevvlgsdr aikflylatg. The homology search for the sequence revealed it to be an Apoptosis Inducing Factor (AIF).

Conclusion

Results indicate that the secretion of PID15 is dependent on concentration of NV-PLA₂ treatment, incubation time and also on temperature and the probable membrane origin of PID15 and not of cytosolic origin with apoptosis inducing ability.

Early Treatment with Intranasal Neostigmine Reduces Mortality in a Mouse Model of Naja naja (Indian Cobra) Envenomation

Objective. Most snakebite deaths occur prior to hospital arrival; yet inexpensive, effective, and easy to administer out-of-hospital treatments do not exist. Acetylcholinesterase inhibitors can be therapeutic in neurotoxic envenomations when administered intravenously, but nasally delivered drugs could facilitate prehospital therapy for these patients. We tested the feasibility of this idea in experimentally envenomed mice. Methods. Mice received intraperitoneal injections of Naja naja venom 2.5 to 10 times the estimated LD50 and then received 5 μL neostigmine (0.5 mg/mL) or 5 μL normal saline by nasal administration. Animals were observed up to 12 hours and survivors were euthanized. Results. 100% of control mice died. Untreated mice injected with 2.5× LD50 Naja naja died at average 193 minutes after injection, while 10 of 15 (67%) of treated mice survived and were behaviorally normal by 6 hours (P < 0.02). In the 5× LD50 group, survival was prolonged from 45 minutes to 196 minutes (P = 0.01) and for 10× LD50 mice, survival increased from 30 to 175 minutes (P < 0.02). Conclusion. This pilot suggests that intranasal drugs can improve survival and is the first direct demonstration that such an approach is plausible, suggesting means by which treatment could be initiated before reaching the hospital. Further investigation of this approach to neurotoxic and other types of envenomation is warranted.

A multicomponent strategy to improve the availability of antivenom for treating snakebite envenoming

Snakebite envenoming is a common but neglected public health problem, particularly in impoverished rural regions of sub-Saharan Africa, Asia and Latin America. The only validated treatment for this condition is passive immunotherapy with safe and effective animal-derived antivenoms. However, there is a long-lasting crisis in the availability of these life-saving medications, particularly in sub-Saharan Africa and parts of Asia. We herein advocate a multicomponent strategy to substantially improve the availability of safe and effective antivenoms at the global level. This strategy is based on: (i) preparing validated collections of representative venom pools from the most medically dangerous snakes in high-risk regions of the world; (ii) strengthening the capacity of national antivenom manufacturing and quality control laboratories and their regulatory authorities and establishing new facilities in developing countries through technology transfer, as an integral part of efforts to develop their biological products industry; (iii) getting established laboratories to generate antivenoms for various regions of the world; and (iv) getting governments and relevant organizations to give snakebite envenoming due recognition within national and international public health policy frameworks. These ways of making antivenom available should be complemented by actions to improve health information systems, the accessibility of antivenoms, the training of medical and nursing staff, and community-based education. Such a multicomponent strategy involving stakeholders on many levels could help consolidate sustainable improvements in antivenom availability worldwide.