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Venomous Snakes: A Neglected Hazard for Outdoor Workers

July 9, 2019 by Stephanie Pendergrass, M.S.

Copperhead: Photo courtesy of U.S. Fish and Wildlife Service

Outdoor workers can experience a number of hazards. One often unexpected hazard is a venomous snakebite. Venomous snakes may be encountered in workplaces throughout the United States. The most likely geographic locations where outdoor workers would encounter venomous snakes is in the American South, Southwest, and West. From 2008-2015, the greatest number of deaths from venomous snakebites occurred in the southern and mid-western United States [Forrester et al., 2018]. The number of venomous snakebites is gradually increasing in most states [Schulte, 2017]. The risk of worker encounters with venomous snakes outside these areas may increase as changes in local climate allow venomous snake species to expand into ever more favorable habitats [Yanez-Arenas et al., 2016]. Additionally, extreme weather events such as hurricanes, floods and droughts, may affect the risk of worker encounters with venomous snakes [Wozniak et al., 2006]. For example, a 20-year study in California found that snakebites increased after precipitation events and decreased during droughts [Phillips et al., 2018]. Other factors affecting human-venomous snake encounters include human encroachment into snake habitat, animal displacement during and after a natural disasters (tornadoes, hurricanes, floods), and extended periods of unseasonably warm and humid weather [Fraizer, 2018; Jones and Baker, 2012].

Outdoor occupations most likely to encounter venomous snakes include: park rangers, landscapers, farmers, groundskeepers, zoo workers, foresters, gardeners, laborers, construction workers, painters, church pastors (snake handling during church services), and reptile handlers. During the period January 1, 2014 to November 5, 2015, 180 adult snakebites were reported to the ToxIC North American Snakebite Registry, of which 25 (13.9%) occurred while working [Spyres et al., 2016]. The state with the greatest number of occupational venomous snakebites was Arizona with 13 cases (17%), followed by Texas with 4 (11%) [Spyres et al., 2016]. Landscape workers (28%) and zoo workers/exotic reptile industry workers (24%) were the occupations with the greatest number of venomous snakebites [Spyres et al, 2016].

Examination of data from the American Association of Poison Control Centers, covering the time period from 2006-2015, found there were 65,695 reported venomous snake exposures with 31 deaths [Mowry, Spyker et al., 2016]. The low number of deaths in the United States is due to the availability of antivenin (antivenom) and advanced medical care [Sanders, 2015]. Contrast this with the World Health Organization’s (WHO) estimate of 1.8-2.7 million venomous snakebites worldwide and between 81,000-137,000 deaths from snakebites [WHO, 2019].

The venomous snakes that are native to the United States include rattlesnakes, copperheads, water moccasins (cottonmouth), and coral snakes. Pit Vipers, such as rattlesnakes, copperheads, and water moccasins have slit-like pupils, triangular heads (due to venom pouches), and a pit located between the eyes and nostrils). Elapids, like the coral snake, have brilliantly colored bands (red, black, and yellow), and can be confused with non-venomous snakes such as the scarlet kingsnake, Mexican milk snake, and red milk snake. To help differentiate between coral snakes and their mimics, it is helpful to remember “red on black, friend of Jack; red on yellow, kill a fellow”.

Signs and Symptoms

The signs and symptoms that develop from venomous snakebites may vary in severity based on the type and amount of venom injected. Chronic medical conditions, medications, and age may increase sensitivity to the effects of venom and worsen outcomes [Spyres et al., 2018; Tekin et al., 2015; Dubinsky, 1996]. Due to the complexity of snake venom components, the victim of a venomous snakebite may exhibit a combination of clinical manifestations ranging from localized tissue damage to life-threatening systemic effects [Parker-Cote and Meggs, 2018; Adukauskiene et al., 2011; Pizon, 2007; Cribari, 2004]:

Pain/burning sensation at the bite site that progresses away from the bite site.
Increased bleeding and bruising
Dizziness
Blurry Vision
Increased sweating
Difficulty breathing
Tingling/numbness around the mouth
Nausea and vomiting
Paleness and feeling cold (along with low blood pressure, nausea, sweating – are signs of shock and anaphylaxsis) [Esiene et al., 2019; Zad et al., 2009; Norris et al., 2007].
Decreased consciousness
Paralysis
Cardiovascular system collapse
Coma
Death

How to Prevent Venomous SnakeBites

What Employers Can Do:

Treat the possibility of venomous snakebites as a workplace hazard.

Educate employees on how to identify and avoid the venomous snakes at the worksite.

Emphasize “Situational Awareness” and educate employees about how to prevent snakebites (e.g., avoid putting hands or feet into places that cannot be visually inspected).
Consider providing employees with appropriate personal protective equipment (PPE) – snake proof boots or puncture-proof gaiters, and leather or Kevlar gloves [Gonzaga et al., 2016].
Develop and practice an emergency response plan for venomous snakebites so that employees know what they should do if bitten by a snake.
During responses to natural disasters, the leader/coordinator (e.g., Incident Commander) coordinating disaster recovery efforts should conduct a risk assessment that includes the likelihood of human-snake encounters and venomous snakebites.

What Employees Can Do:

Be aware of your surrounding environment.
If you encounter any snake, do NOT handle it (most bites occur when humans try to catch or kill venomous snakes) – Leave the snake alone and notify other workers of the snake’s location and description.
Do NOT disregard the bites of small or juvenile venomous snakes. They are born equipped with venom that is just as potent as adult venomous snakes.
Wear appropriate PPE and protective clothing such as snake-proof boots, leather gloves, and long pants when working outdoors.
Wear leather gloves and use tools to move brush piles, leaves, wood, metal, and debris by lifting the far side toward you as this creates a barrier between the worker and any venomous snakes.
Be aware that snakes are more active in warm weather and at night.
Make noise as snakes will tend to avoid it (while snakes do not have external ears, they are equipped with an inner ear that can feel vibrations from noise, e.g. footsteps, voices).
Workers [Federal Emergency Management Agency (FEMA), military, police/fire/EMS, veterinarians, U.S. Public Health Service, etc.] responding to natural disasters (hurricanes, tornados, floods, droughts, etc.) should exercise caution and understand that like people, venomous snakes will be displaced and looking for safe, dry, inhabitable areas, too [Jones and Baker, 2012; Wozniak et al., 2006].

What to Do If You or a Coworker Are Bitten

Move the bitten person away from striking distance of the snake (approximately one-half to two thirds the length of the snake) to avoid additional bites.
Stay Calm! Call 9-1-1 or have someone else call 9-1-1. Always treat snakebites as an emergency!
Notify your supervisor and other employees.
Observe the bite area for 2 puncture wounds (fang wounds). The “absence” of visible fang marks is NOT evidence of a lack of a venomous snake bite. Some venomous snakes have very small fangs (coral snakes) and the punctures may not be visible to the human eye.
Have someone identify or take a picture of the snake if possible – do not approach or attempt to catch or kill the snake! The emergency room (ER) does NOT want the snake!
Restrict movement and keep the bite area below the heart. Movement and elevation of the bite area above the heart will increase the heart rate and the rate at which the venom moves through the body.
If possible, wash the bite area with soap and water as soon as possible.
Cover wound with clean, dry bandage.
If EMS is not readily available, apply first aid (on the way to the ER if possible) and begin transport of the victim to the nearest ER.

Additional Note: After a venomous snakebite, there is the possibility that the bite victim may experience an anaphylactic reaction (severe allergic reaction) to the snake venom and in some cases, the antivenom used to treat snake bites [Rencher et al., 2018; Bebarta et al., 2010; de Medeiros et al., 2008; Cannon et al., 2008; Prescott and Potter, 2005; Brooks et al., 2004; Camilleri and Offerman, 2004]. Snake venom, basically highly modified saliva, is comprised of protein (80%) and enzymes (20%), that can trigger anaphylactic reactions in some people. Additionally, elderly workers may have increased susceptibility because co-morbidities and medications that may increase their risk of blood loss and tissue damage (Spryes et al., 2018; Feitosa et al., 2015). If the victim experiences an anaphylactic reaction, emergency medical treatment is needed.If EMS care is not immediately available, and the victim has received first aid, the spread of venom can be monitored by the location of pain and swelling. Make a mark every 15 minutes at the leading margins of the pain and swelling and note the time. This will assist the ER physician in determining how fast the venom is spreading and an idea of the amount of tissue damage.

What NOT to Do

Do not wait to seek immediate medical attention if bitten.
Do not attempt to capture or kill the snake.
Do not apply ice to the bite area.
Do not apply a tourniquet or tourniquets.
Do not immerse in water or other liquids.
Do not cut bite wounds and/or attempt to suck out the venom.
Do not drink alcohol or caffeinated beverages.

We hope that this blog will increase awareness and knowledge about the risk that venomous snakes can pose to outdoor workers. Employers and their employees should be aware of the dangers of outdoor work in areas where venomous snakes may be present. The knowledge of native snakes, along with the use of safe work practices, can prevent and lessen the risk to workers in areas where venomous snakes are prevalent. Additional information can be found on the NIOSH venomous snakes webpage. Please share with us any workplace practices, methods, procedures, or tools that have helped to protect workers from venomous snakes and related hazards. We are always interested in information that will help improve workplace safety and health.

Stephanie Pendergrass, M.S., is a research chemist, biologist, AEMT, and Herpetologist in the NIOSH Division of Science Integration.

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July 9, 2019 by Stephanie Pendergrass, M.S.