Twelve month prospective study of snakebite in a major teaching hospital in Mandalay, Myanmar; Myanmar Snakebite Project (MSP)

Snakebite-Associated Infections: A Systematic Review and Meta-Analysis

Snakebites still constitute a significant public health problem in developing countries and are considered a neglected tropical condition by the WHO. Snake accidents are associated with substantial morbidity and mortality and may produce secondary complications, such as severe infections. The objective of this systematic review was to determine the prevalence of snakebite infections and characterize the bacteria isolated from these infections. A systematic literature review in five databases was carried out to assess the prevalence of snakebite infection. A meta-analysis was performed using a random-effects model to calculate the pooled prevalence and 95% CIs. Cochran's Q test and the I2 statistic were used to assess between-study heterogeneity. The pooled prevalence of infection due to snakebite was 27.0% (95% CI: 22.0-32.0%), with high heterogeneity among studies (I2 = 99.7%). The prevalence was higher in Asia (32%) than in the Americas (21%). Snakebite infections required surgical interventions in 68% (95% CI: 37.0-98.0%). The leading group of pathogens identified corresponded to Gram-negative bacteria (63%), particularly Morganella morganii (32%), but also, Gram-positive cocci (40%), especially Enterococcus spp. (23%) and Staphylococcus aureus (15%). However, multiple other pathogens, including anaerobes, were found. A high prevalence of snakebite-associated infection has been described, primarily due to M. morganii, with the corresponding implications for empirical therapy. Rational use of antimicrobials is recommended, and this should guide initial empirical treatment. Moreover, isolation and identification of the possible bacteria present in snakebite wounds is recommended in all cases to confirm or rule out associated infection.

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.

Risk factors and outcome of acute kidney injury in children with snake envenomation

Our study evaluates the risk factors of acute kidney injury (AKI) in children with snake envenomation. Out of 145 cases, 54 (37%) developed AKI. Unsurprisingly, the mortality increased with oliguria and higher levels of creatinine. Bleeding manifestations were also more common among the AKI group.

Panhypopituitarism and Central Diabetes Insipidus Almost Three Decades After Russell's Viper Envenomation: A Remarkable Case Report and Literature Review

BACKGROUND

Snakebite is a preventable yet often-neglected public health hazard with high chronic disability and mortality, mainly faced by rural communities in the tropics/subtropics. Endocrinological disorders following snakebite (especially Russell's viper in India) are notably underrecognized and can lead to remarkable morbidity, poor quality of life, and cardiovascular mortality. Anterior pituitary insufficiency has been the most common ailment following Russell's viper envenomation amid those endocrinological dysfunctions. On the contrary, the posterior pituitary and nearby hypothalamus mostly remain unharmed, so central diabetes insipidus is extremely rare following a viperid snakebite envenomation.

CASE PRESENTATION

The authors present a patient developing panhypopituitarism with evident spontaneous central diabetes insipidus 29 years after Russell's viper envenomation. Relevant investigations ruled out other possible etiologies, and he responded well to hormonal replacement therapy.

CONCLUSIONS

Panhypopituitarism with concurrent central diabetes insipidus may occur following snakebite (especially in Russell's viper envenomation). Early recognition and proper management of these complications are quintessential to preventing further misdiagnosis, under-recognition, morbidity, impaired quality of life, and mortality.

Snakebite Envenoming Diagnosis and Diagnostics

Snakebite envenoming is predominantly an occupational disease of the rural tropics, causing death or permanent disability to hundreds of thousands of victims annually. The diagnosis of snakebite envenoming is commonly based on a combination of patient history and a syndromic approach. However, the availability of auxiliary diagnostic tests at the disposal of the clinicians vary from country to country, and the level of experience within snakebite diagnosis and intervention may be quite different for clinicians from different hospitals. As such, achieving timely diagnosis, and thus treatment, is a challenge faced by treating personnel around the globe. For years, much effort has gone into developing novel diagnostics to support diagnosis of snakebite victims, especially in rural areas of the tropics. Gaining access to affordable and rapid diagnostics could potentially facilitate more favorable patient outcomes due to early and appropriate treatment. This review aims to highlight regional differences in epidemiology and clinical snakebite management on a global scale, including an overview of the past and ongoing research efforts within snakebite diagnostics. Finally, the review is rounded off with a discussion on design considerations and potential benefits of novel snakebite diagnostics.

Systematic Review of Human Poisoning and Toxic Exposures in Myanmar

The International Health Regulations (2005) promote national capacity in core institutions so that countries can better detect, respond to and recover from public health emergencies. In accordance with the ‘all hazards’ approach to public health risk, this systematic review examines poisoning and toxic exposures in Myanmar. A systematic literature search was undertaken to find articles pertaining to poisoning in Myanmar published between 1998 and 2020. A number of poisoning risks are identified in this review, including snakebites, heavy metals, drugs of abuse, agrochemicals and traditional medicine. Patterns of poisoning presented in the literature diverge from poisoning priorities reported in other lower-middle income countries in the region. The experience of professionals working in a Yangon-based poison treatment unit also indicate that frequently observed poisoning as a result of pharmaceuticals, methanol, and petroleum products was absent from the literature. Other notable gaps in the available research include assessments of the public health burden of poisoning through self-harm, household exposures to chemicals, paediatric risk and women’s occupational risk of poisoning. There is a limited amount of research available on poisoning outcomes and routes of exposure in Myanmar. Further investigation and research are warranted to provide a more complete assessment of poisoning risk and incidence.

A Bayesian phase 2 model based adaptive design to optimise antivenom dosing: Application to a dose-finding trial for a novel Russell's viper antivenom in Myanmar

For most antivenoms there is little information from clinical studies to infer the relationship between dose and efficacy or dose and toxicity. Antivenom dose-finding studies usually recruit too few patients (e.g. fewer than 20) relative to clinically significant event rates (e.g. 5%). Model based adaptive dose-finding studies make efficient use of accrued patient data by using information across dosing levels, and converge rapidly to the contextually defined 'optimal dose'. Adequate sample sizes for adaptive dose-finding trials can be determined by simulation. We propose a model based, Bayesian phase 2 type, adaptive clinical trial design for the characterisation of optimal initial antivenom doses in contexts where both efficacy and toxicity are measured as binary endpoints. This design is illustrated in the context of dose-finding for Daboia siamensis (Eastern Russell's viper) envenoming in Myanmar. The design formalises the optimal initial dose of antivenom as the dose closest to that giving a pre-specified desired efficacy, but resulting in less than a pre-specified maximum toxicity. For Daboia siamensis envenoming, efficacy is defined as the restoration of blood coagulability within six hours, and toxicity is defined as anaphylaxis. Comprehensive simulation studies compared the expected behaviour of the model based design to a simpler rule based design (a modified '3+3' design). The model based design can identify an optimal dose after fewer patients relative to the rule based design. Open source code for the simulations is made available in order to determine adequate sample sizes for future adaptive snakebite trials. Antivenom dose-finding trials would benefit from using standard model based adaptive designs. Dose-finding trials where rare events (e.g. 5% occurrence) are of clinical importance necessitate larger sample sizes than current practice. We will apply the model based design to determine a safe and efficacious dose for a novel lyophilised antivenom to treat Daboia siamensis envenoming in Myanmar.

Clinical importance of the Mandalay spitting cobra (Naja mandalayensis) in Upper Myanmar - Bites, envenoming and ophthalmia

Examination of 18 cobras brought to three hospitals in the Mandalay Region by patients bitten or spat at by them distinguished 3 monocled cobras (Naja kaouthia) and 15 Mandalay spitting cobras (N. mandalayensis), based on their morphological characteristics. We confirm and extend the known distributions and habitats of both N. mandalayensis and N. kaouthia in Upper Myanmar. Clinical symptoms of local and systemic envenoming by N. mandalayensis are described for the first time. These included local swelling, blistering and necrosis and life-threatening systemic neurotoxicity. More information is needed about the clinical phenotype and management of bites by N. mandalayensis, the commoner of the two cobras in Upper Myanmar. Since the current cobra antivenom manufactured in Myanmar has lower pre-clinical efficacy against N. mandalayensis than N. kaouthia, there is a need for more specific antivenom therapy.

Complementary DNA library of Myanmar Russell's viper (Daboia russelii siamensis) venom gland

Geographical variations of snake venoms of the same species are well-known. Exploring the components of venom from each region will give insights in its distinctive toxicities. Venom gland cDNA library of Russell's viper (RV) from Myanmar (Daboia russelii siamensis) was constructed to create a catalog of expressed sequences tags (ESTs) and to compare with sequences from RV of other countries. The cDNA library of venom gland was generated by using CloneMiner™ II cDNA Library Construction Kit. Clones were subjected to Sanger sequencing and analyses by bioinformatics tools. From 251 isolated clones, 38 ESTs were assembled into 6 clusters and 21 singlets. Toxin sequences contributed to 57.9% of all transcripts and Kunitz-type serine protease inhibitors are most abundant (45.5% of toxin transcripts). The Myanmar RV phospholipase A2 (PLA2) showed 98% and 74% identity to D. r. russelii PLA2 from India (DrK-bI) and PLA2 of D. r. siamensis from Thailand as well as Taiwan, respectively. The cysteine-rich secretory protein (CRISP) homologs from Myanmar RV were first identified here showing homology to CRISP from Taiwan RV and European vipers with 98% and 90% identity, respectively. The RV 5' nucleotidase was also first cloned. In summary, Myanmar RV showed a unique gene expression pattern and sequences. Large scale analysis by next-generation sequencing is warranted.