Snakebite Risk Research Articles

The Global Snake Bite Initiative: an antidote for snake bite

Clinicians have for a long time witnessed the tragedy of injury, disability, and death from snake bite that is a daily occurrence in many parts of Africa, Asia, and Latin America. To many people living in these regions, including some of the world's poorest communities, snake bite is an ever present occupational risk and environmental hazard, an additional penalty of poverty. Like malaria, dengue, tuberculosis, and parasitic diseases, the risk of snake bite is always present. Unlike many of these other public health risks, however, the burden of human suffering caused by snake bite remains unrecognised, invisible, and unheard by the global public health community, forgotten by development agencies and governments alike.

Protection against Snake Bites by Sleeping under a Bed Net in Southeastern Nepal

Snake bites in persons while they are asleep indoors are associated with a high risk of fatal outcome in southeastern Nepal. The preventive impact of sleeping under a bed net was assessed in four villages in a case-control study. A case was defined as a person with a history of snake bite that occurred indoors while asleep. Cases were matched with controls by village, type of household, sex, and age category. Of the 11,176 households visited, 56 cases, including 13 (23%) with a fatal outcome and 56 controls were included in the analysis. Sleeping under a bed net was a strong protective factor (odds ratio = 0.02, 95% confidence interval = 0.007-0.07, P < 0.0001), whereas the place of sleeping in the household and the use of a cot were not associated with the risk of snake bite. These findings provide further support for use of bed nets in this region.

374. Development of a Genetic Vaccine Conferring Protective Immunity Against α-Cobratoxin Following a Single Administration of an Adenovirus Vector Encoding a Modified, Non-Toxic Cobratoxin Variant

Approximately 300,000 venomous snakebites occur throughout the world each year, almost 40,000 of which result in death. Little has changed over the past century regarding the medical approach to the risk of snakebite, and there are no vaccines available to protect against the common poisonous snakes. The present study presents a new paradigm for the development of vaccines to protect against snakebite, using knowledge of the structure and action of specific toxins combined with a gene-based strategy to deliver a toxin gene modified to render it non-toxic while maintaining its 3-dimensional structure and hence its ability to function as an immunogen. As a model for this approach, we developed a genetic vaccine to protect against α-cobratoxin (CTX), a potent, post-synaptic neurotoxin that is the major toxic component of the venom of Naja naja kathouia, the spectacled cobra. To develop the vaccine, substitutions in the CTX cDNA were introduced at 2 residues critical for binding to the nicotinic acetylcholine receptor (Asp27 to Arg, Arg33 to Gly) and a third substitution (Val37) which was silent at the amino acid level. The mutated CTX (mCTX) retained the overall antigenic structure of native CTX, while reducing receptor binding 10,000-fold (Fruchart-Gaillard et al. Proc Natl Acad Sci USA 2002; 99: 3216–3221). The mutated CTX expression cassette was delivered either as a plasmid (pmCTX) or in the context of a replication deficient adenovirus vector (AdmCTX). To assess whether expression of the mutated CTX in vivo leads to the development of protective immunity, BALB/c mice were challenged by IV administration of 2 μg of α-cobratoxin protein 21 days after IV injection of the mCTX plasmid vaccine. For animals receiving either no treatment (naive) or IV injection of Null plasmid, 80% died from the α-cobratoxin challenge. However, 100% of animals receiving a single IV dose of the mCTX plasmid vaccine survived, i.e., not only was it safe to express the mutated cobratoxin, but it evoked protective immunity. Similarly, BALB/c mice were challenged by IV administration of 2 μg of α-cobratoxin protein 21 days after IV injection of 109 particle units of AdmCTX (the vaccine in the context of an Ad vector) or AdNull (as a control). Animals receiving AdmCTX or AdNull and no challenge suffered no ill effects, but ≥80% of naive animals or those receiving AdNull died within10 min from the CTX protein challenge. In contrast, 100% of animals receiving a single IV dose of AdmCTX 21 days prior to challenge survived. The data demonstrates that both plasmid and adenovirus-based vaccines can be developed to protect against lethal challenge with α-cobratoxin. The effectiveness of this approach might serve as a basis to consider the development of a global public health program to protect the lives of those at risk for death by snakebite.

Snakebite: Epidemiology, Prevention, Clinical Presentation and Management

Snakebite: Epidemiology, Prevention, Clinical Presentation and Management

Fatal snakebite in Australia.

More than 20 venomous snakes found in Australia belong to the family Elapidae . Although their venom delivery system is less efficient than that of the Viperidae , their venoms are extremely potent. The active components of Australian elapid venoms include neurotoxins, myotoxins , hemolysins, and factors producing hypocoagulability. The groups at particular risk of snakebite are children, agricultural workers, bushwalkers , and herpetologists . A high index of suspicion must be maintained when investigating cases of sudden unexpected death in these groups. The bite wound itself may be particularly easily overlooked as there is little local reaction to many elapid bites. The necropsy findings in fatalities are predictable from the known properties of the venoms of the various species. However, these findings are non-specific and the diagnosis ultimately rests upon the demonstration of the presence of venom by immunoassay. For this purpose swabs from the bite site, the overlying clothing, the excised bite site, the local and regional lymph nodes, urine, and blood may be used.