Antivenom therapy of carpet viper (Echis ocellatus) envenoming: effectiveness and strategies for delivery in West Africa.

In West Africa, response to specific, geographically appropriate, antivenom is often dramatic following carpet viper (Echis ocellatus) envenoming with rapid restoration of blood coagulability and resolution of spontaneous haemorrhage. Envenoming from Australasian snakes causing similar coagulopathies may respond less dramatically and the effectiveness of antivenom is being questioned. Here we have reviewed and re-analysed all published preclinical and clinical studies on envenoming and antivenom therapy conducted in West Africa to determine the effectiveness of antivenom. 22 studies provided relevant information: 12 observational studies, 4 RCTs and 6 preclinical studies. Four comparative studies confirmed statistically significant protection against mortality ranging from 57 to 87% using specific antivenoms compared to non-specific or no antivenoms. Meta-analysis estimated combined Odds Ratio (95% CI) of 0.25 (0.14-0.45) of dying among those treated with specific antivenom or 75% (95% CI: 55-86%) protection against death. Mortality more than doubled during times when stocks of reliable antivenoms ran out, with Relative Risk (95% CI)] of 2.33 (1.26-4.06). Serum kinetics of venom antigen/antivenom levels also confirmed that decline of venom antigen levels coincided with resolution of coagulopathy while decline of antivenom levels was associated with venom antigen reappearance and recurrence of coagulopathy. Preclinical and antivenomics analysis confirmed efficacy of regionally appropriate antivenoms against E. ocellatus and related species' venoms in Sub-Saharan Africa but not against Asian Echis carinatus venom. Antivenoms raised against E. carinatus were ineffective in human studies. In West Africa, specific antivenom is effective in managing carpet viper envenoming. A centralized hub-and-spoke strategy is suggested for broadening antivenom access to endemic rural areas together with instituting quality assurance, standardization and manpower training. Benefits, risks, cost-effectiveness and feasibility of the approach should be formally assessed.

Snakebite envenoming from a global perspective: Towards an integrated approach.

Snakebite envenoming is a neglected public health challenge of compelling importance in many regions of the world, particularly sub-Saharan Africa, Asia, Latin America and Papua-New Guinea. Addressing the problem of snakebite effectively demands an integrated multifocal approach, targeting complex problems and involving many participants. It must comprise: (a) Acquisition of reliable information on the incidence and mortality attributable to snakebite envenoming, and the number of people left with permanent sequelae. (b) Improvements in production of effective and safe antivenoms, through strategies aimed at strengthening the technological capacity of antivenom manufacturing laboratories. (c) Increasing the capacity of low-income countries to produce specific immunogens(snake venoms) locally, and to perform their own quality control of antivenoms. (d) Commitments from regional producers to manufacture antivenoms for countries where antivenom production is not currently feasible. (e) Implementation of financial initiatives guaranteeing the acquisition of adequate volumes of antivenom at affordable prices in low-income countries. (f) Performance of collaborative studies on the safety and effectiveness of antivenoms assessed preclinically and by properly designed clinical trials. (g) Development of antivenom distribution programmes tailored to the real needs and epidemiological situations of rural areas in each country. (h) Permanent training programmes for health staff, particularly in rural areas where snakebites are frequent.(i) Implementation of programmes to support those people whose snakebites resulted in chronic disabilities. (j) Preventive and educational programmes at the community level, with the active involvement of local organizations and employing modern methods of health promotion. Such an integrated approach, currently being fostered by the Global Snake Bite Initiative of the International Society on Toxinology and by the World Health Organization, will help to alleviate the enormous burden of human suffering inflicted by snakebite envenoming.

Unscrupulous marketing of snake bite antivenoms in Africa and Papua New Guinea: choosing the right product--'what's in a name?'.

Snake bite envenoming, mainly caused by the saw-scaled or carpet viper (Echis ocellatus), is a neglected disease of West Africa. Specific antivenoms can save life and limb but, for various reasons, supply of these essential drugs to Africa has dwindled to less than 2% of estimated requirements. Other problems include maldistribution, inadequate conservation and inappropriate clinical use of antivenoms. In the face of this crisis, several promising new antivenoms have been developed. However, some dangerously inappropriate products of Indian origin are being marketed by unscrupulous manufacturers or distributors in Africa and Papua New Guinea, with disastrous results. A major source of confusion is labelling antivenom with ambiguous snake names that fail to distinguish the Asian species whose venoms are used in their production from the local snakes whose venoms are antigenically dissimilar.

Physical vulnerability and fatal self-harm in the elderly.

Although the high rate of suicide in elderly people is conventionally explained as being due to greater intent to die, we have noted elderly Sri Lankans dying after relatively mild poisoning. Using data from cases of yellow oleander poisoning, we investigated the effect of age on outcome in 1697 patients, controlling for gender and amount ingested. In fully adjusted models, people over 64 years old were 13.8 (95% CI 3.6-53.0) times more likely to die than those less than 25 years old. The high number of suicides in elderly people globally is likely to be due, in part, to the difficulty they face in surviving the effects of both the poisoning and its treatment.