WHO updates fact sheet on snake antivenoms (18 September 2017)

The World Health Organization (WHO) has recently updated its fact sheet on snake antivenoms.

Key Messages:

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 envenomings.

81 000 to 130 000 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.

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.

A significant challenge in manufacturing of antivenoms is the preparation of the correct immunogens (snake venoms). At present very few countries have capacity to produce snake venoms of adequate quality for antivenom manufacture, and many manufacturers rely on common commercial sources.

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 data on the number and type of snake bites have led to difficulty in estimating needs, and deficient distribution policies have further contributed to manufacturers stopping production or increasing the prices of antivenoms.

Under-reporting of snake bite incidence and mortality is common:

In Nepal, for example, where 90% of the population lives in rural areas, the Ministry of Health reported 480 snake bites resulting in 22 deaths for the year 2000, yet figures for the same year collected in a community based study of one region (Eastern Nepal) detailed 4078 bites and 396 deaths.
Likewise, a very large community- level study of snakebite deaths in India gave a direct estimate of 45 ,900 (99% CI: 40,900-50,900) deaths in 2005, which is over 30 times higher than the Government of India’s official figure.

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

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.

Following a request by several UN member states, WHO formally listed snakebite envenoming as a highest priority neglected tropical disease in June 2017.

Two tools to help guide the development of appropriate antivenoms have been launched:

These tools will assist:

public health officials in determining what antivenoms are needed in their country and in drafting relevant national public health policies;
national regulators in prioritizing antivenoms for registration and assessing safety, quality, and efficacy of antivenoms to meet national public health needs;
procurement agencies in selecting appropriate antivenoms for national treatment needs;
antivenom manufacturers in developing plans for production and sale of appropriate antivenoms;
clinicians and health care professionals in treating snakebites; and
general population in knowing and being able to identify which venomous snakes live in their area.