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Snakebite: An underestimated cause of accidental death

A snakebite is an injury caused by the bite of a snake, especially a venomous snake. A common symptom of a bite from a venomous snake is the presence of two puncture wounds from the animal’s fangs.

Human-animal conflict

To accommodate the ever-increasing human population, the habitat of animals is shrinking resulting in human-animal conflict and snakes are not an exception.

The study in 2011 of snakebite mortality in India found that about 46,000 people die of snakebite every year, eclipsing the figures provided by government hospitals of around 1,400 deaths annually.
The report said: “Thus, snakebite remains an underestimated cause of accidental death in modern India, causing about one death for every two HIV-related deaths.” In contrast, the number of human deaths caused by elephants is anywhere between 100 and 300 a year.

Experts working with snakes and among farm communities have said that the problem is largely invisible because it affects the rural poor. When rural people were asked to mention three fears of the forest, “Snakebite will feature in the first three every time.”

Key facts

Though the exact number of snake bites is unknown, an estimated 5.4 million people are bitten each year with up to 2.7 million envenoming (poisoning from snake bites).

Around 81,000 to 1,38,000 people die each year as a result of snake bites, and around three times as many amputations and other permanent disabilities are caused by snakebites annually.

The snakes responsible for a majority of deaths are highly adaptable to their surroundings and habitat are “big four” species – Russel’s viper, Indian krait, spectacled cobra and saw-scaled viper. “Out of some 300 snakes, only 10 to 15 can kill humans,” according to available information, “Out of that, only four are commonly found across the country. A large number of snakebites are non-venomous or only slightly venomous.”

A lack of awareness in general about snakebites also means that few rural doctors know how to treat such or administer antivenom. Misadministering the serum can lead to anaphylactic shock, a life-threatening allergic reaction, and death.

Snake venom and its potency differ between species, and even between snakes of the same species between regions. Bites by venomous snakes can cause paralysis that may prevent breathing, bleeding disorders that can lead to a fatal haemorrhage, irreversible kidney failure and tissue damage that can cause permanent disability and limb amputation.

Agricultural workers and children are the most affected. Children often suffer more severe effects than adults, due to their smaller body mass.

Global situation

In Asia, up to 2 million people are envenomed by snakes each year, while in Africa there are an estimated 4,35,000 to 5,80,000 snake bites annually that need treatment. The highest burden occurs in countries where health systems are weakest and medical resources sparse.

In contrast to many other serious health conditions, a highly effective treatment exists for snakebite. Most deaths and serious consequences from snake bites are entirely preventable by making safe and effective antivenoms more widely available and accessible. High-quality snake antivenoms are the only effective treatment to prevent or reverse most of the venomous effects of snake bites. They are included in the WHO List of essential medicines and should be part of any primary health care package where snake bites occur.

Challenges producing antivenoms:

A significant challenge in the manufacturing of antivenoms is the preparation of the correct immunogens (snake venoms). At present, very few countries have the capacity to produce snake venoms of adequate quality for antivenom manufacture, and many manufacturers rely on common commercial sources. These may not properly reflect the geographical variation that occurs in the venoms of some widespread species. In addition, lack of regulatory capacity for the control of antivenoms in countries with significant snake bite problems results in an inability to assess the quality and appropriateness of the antivenoms.

Poor regulation and the marketing of inappropriate or poor quality antivenoms have also resulted in a loss of confidence in some of the available antivenoms by clinicians, health managers, and patients, which has further eroded demand.

Weak health systems and lack of data

Health systems in many countries where snake bites are common often lack the infrastructure and resources to collect robust statistical data on the problem. Assessing the true impact is further complicated by the fact that cases reported to health ministries by clinics and hospitals are often only a small proportion of the actual burden because many victims never reach primary care facilities, and are therefore unreported. This is contributed to by socio-economic and cultural factors that influence treatment-seeking behaviour with many victims opting for traditional practices rather than hospital care. Under-reporting of snakebite incidence and mortality is common.

Given low demand, several manufacturers have ceased production, and the price of some antivenom products have dramatically increased in the last 20 years, making treatment unaffordable for the majority of those who need it. Rising prices also further suppress demand, to the extent that antivenom availability has declined significantly or even disappeared in some areas. The entry into some markets of inappropriate, untested or even fake antivenom products has also undermined confidence in antivenom therapy generally.

WHO response

World Health Organisation (WHO) has taken steps to raise the awareness of health authorities and policymakers on this issue. In December 2015 a programme to evaluate the potential safety and effectiveness of current antivenom products intended for use in sub-Saharan Africa was launched by the WHO. The results of this detailed technical and laboratory assessment will be published in early 2018. Following a request by the member states, WHO formally listed snakebite envenoming as the highest priority neglected tropical disease in June 2017.

WHO urges regulators, producers, researchers, clinicians, national and regional health authorities, and international and community organizations to work together to improve the availability of reliable epidemiological data on snake bites, the regulatory control of antivenoms and their distribution policies.                                      –                                                                                                           – NAVEED AHAMAD

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