WHO/David Williams
© Credits

Snakebite envenoming

    Overview

    Snakebite envenoming is a potentially life-threatening disease caused by toxins in the bite of a venomous snake. Envenoming can also be caused by having venom sprayed into the eyes by certain species of snakes that have the ability to spit venom as a defence measure.

    Inadequate past efforts to control snakebite envenoming has produced fragmented, inaccurate epidemiological data. Many victims do not attend health centres or hospitals and instead rely on traditional treatments. However, available data show 4.5–5.4 million people get bitten by snakes annually. Of this, 1.8–2.7 million develop clinical illness and 81 000 to 138 000 die from complications.

    High-risk groups include rural agricultural workers, herders, fishermen, hunters, working children, people living in poorly constructed houses and those with limited access to education and healthcare. Morbidity and mortality occur most frequently among young people and children suffer higher case fatality. Furthermore, women experience increased barriers to accessing medical care in some cultures and pregnant women are extremely vulnerable.

    An ongoing crisis restricting access to safe, effective antivenom treatment in many regions, and particularly sub-Saharan Africa, is one factor that contributes to the predisposition for seeking help through traditional medicine. 

    Symptoms

    Bites or sprayed venom from venomous snakes can cause a range of acute and serious medical emergencies. Envenoming from different types of snakes can cause different symptoms, some more serious than others. This makes the preparation of correct antivenoms an ongoing problem. Envenoming can cause severe paralysis that may prevent breathing, making immediate medical attention critical. People may also experience bleeding disorders that can lead to fatal haemorrhages or irreversible kidney failure. Severe local tissue destruction may also occur, which can lead to permanent disability and even limb amputation. Children are at higher risk of severe effects due to lower body mass than adults.

    Most deaths and serious consequences from snake bites are entirely preventable by making safe and effective antivenoms more widely available and accessible, particularly in high-risk areas. High quality snake antivenoms are the only effective treatment to prevent or reverse most of the venomous effects of snake bites.

    Treatment

    Snake antivenoms are effective treatments to prevent or reverse most of the harmful effects of snakebite envenoming and are included in the WHO list of essential medicines. The availability and accessibility of these antivenoms, along with raising awareness on primary prevention methods among communities and health workers, are the best ways to limit serious consequences and deaths from snakebite envenoming.

    After a bite by a snake suspected of being venomous, follow these steps:

    • Immediately move away from the area where the bite occurred.
    • Remove anything tight from around the bitten part of the body to avoid harm if swelling occurs.
    • Reassure the victim, as most venomous snake bites do not cause immediate death.
    • Immobilize the person completely and transport the person to a health facility as soon as possible
    • Applying pressure at the bite site with a pressure pad may be suitable in some cases.
    • Avoid traditional first aid methods or herbal medicines.
    • Paracetamol may be given for local pain (which can be severe).
    • Vomiting may occur, so place the person on their left side in the recovery position.
    • Closely monitor airway and breathing and be ready to resuscitate if necessary

     

     

    Our work

    Improving treatment for snakebite patients

    Improving treatment for snakebite patients

    Nick Ballon/Wellcome Trust
    Extracting snake venom
    © Credits

    Overview

    WHO supports countries and regions to:

    Build capacity for treatment:
    Reducing the problem of snakebite envenoming begins by improving education about its risk and providing training to medical staff and health-care workers in affected countries.
    WHO supports the development of standard treatment guidelines for medical professionals and health-care workers. WHO also participates in the creation of additional training resources for regions and countries adapted to service delivery environments and availability of local resources.

    Provide early access to safe, affordable and effective antivenoms:
    Improving access to antivenoms is essential to minimize morbidity and mortality and is a major component of WHO’s strategy to prevent and control snakebite envenoming. 
    Antivenoms remain the only treatment available to prevent or reverse the effects of snakebite envenoming when administered early and in adequate therapeutic doses. They are included in WHO’s Model List of Essential Medicines.

    Strengthen diagnostics tests and tools:
    Developing new point-of-care diagnostic tools has considerable potential to enhance surveillance of snakebite envenoming by enabling retrospective identification in pathology samples of venom immunotypes from various species of snakes. 
    Strengthened diagnostic tests and tools can improve the reporting of snakebite envenoming and assist in determining optimal antivenom needs for regions.

    Raise awareness of snakebite rehabilitation:
    Increasing awareness of snakebite envenoming as an important public health problem with organizations that work with disabled people in the developing world is essential to improving access and equity for victims. Snake bites can cause a variety of disabilities potentially leading to substantial loss of limb use or even amputation. In some countries victims become mired in poverty and may be socially ostracized.