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Safety and Health of Pacific Island Residents and Tourists

Photograph of a person holding a large snake (probably about 7 to 8 feet in length). Caption reads: 'A large brown tree snake discovered on Guam.' USGS photo by G.H. Rodda.With brown Treesnakes reaching lengths of up to 11 feet (while more commonly 3-6 feet) and attaining densities of 12,000 per square mile, it is not surprising that these mildly venomous snakes have caused problems with native Guamanians as well as tourists.  This is particularly true because the snake-plagued paradise relies heavily on the dollars generated by the tourism industry.  Indeed, only military and government expenditures rival tourism in economic importance.

An example illustrating the potential effect on travelers appeared in Mark Jaffe's novel "And No Birds Sing."  In this instance, a visiting scientist awoke to find himself staring a brown Treesnake in the eye.  Coiled on his chest, it was in pursuit of a gecko on the wall behind him.  Startled by the man's movement, the snake launched and bit him in the cheek.  "If I wasn't a herpetologist, I'd have been on the next plane out of here," he said in response to the incident.  There are also numerous cases of children being bitten in bed while sleeping, and household pets and agricultural animals becoming prey to larger snakes.

Snakes are commonly found in houses and commercial buildings and are a persistent source of irritation and fear to island residents and tourists not accustomed to living with snakes.  Many people have a deep-seated fear of snakes, and the vast majority of people resent snakes inside homes, stores, and other human environments.  The abundance of snakes in close proximity to people in Guam affects people's perceptions of the quality of life on the island.  Snakes startle tourists and power outages frequently cut short their enjoyment of Guam's nightlife in restaurants, discotheques, and shopping centers.  The invasion of homes continues to influence where people live, property values for entire neighborhoods, and decisions about staying on Guam or moving off-island.

Although a dollar amount has not been specifically assigned to the brown Treesnake's impact on Guam's economy as related to tourism, it is estimated that $1-4 million is lost annually due to power outages alone.

Incidence of Snakebite on Guam

Since only two types of snake reside on Guam, the brown Treesnake and a wormlike blind snake (Ramphotyphlops braminus), the latter of which cannot bite humans because of its small size, it is appropriately assumed that all snakebite victims on Guam were bitten by the brown Treesnake.  The majority of the reported cases of snakebites on Guam occurred with small children, although there is the possibility that, since the snake is generally considered harmless, adults that were bitten did not seek medical attention.

Photograph of brown tree snake fang showing the grooves used to inject venom.' USGS photo by K. Jackson.The brown Treesnake is a rear-fanged Colubrid.  It does not use elongated anterior fangs and a quick strike to inject its venom like the more dangerous snakes.  Instead, it utilizes an enlarged Duvernoy's gland and grooves in its rear-posited fangs to envenomate its victim.  Envenomation is accomplished through deliberate chewing to inject venom by means of capillary action along the grooved fang.  The venom is used to subdue and kill the birds, mammals, and lizards on which this snake normally feeds.  The snake often wraps its body around the prey to immobilize it while chewing on the animal.  This factor helps determine the motivation of a snake's strike.  If a snake is found chewing on and constricting its victim, it is exhibiting feeding behavior.  If only one or two quick strikes occur when the snake has been startled, it is generally reacting in defense.

Photograph of the hand of an infant bitten by a brown tree snake showing swelling, discoloration, and bleb formation.' (small water blisters).  USGS photo T.H. Fritts.When threatened, the brown Treesnake is extremely aggressive and likely to lunge and bite.  The bite frequently results in bleeding where the teeth break the human skin and causes local swelling and itching.  The reaction is similar to that of a bee sting.  Some medical risk exists to infants, elderly people, and anyone with extreme allergic reactions suffering serious bites, especially if the snake has been able to chew or hold on after the initial strike.  Children on Guam have been admitted to the hospital for snakebites exhibiting symptoms such as: lethargy, diminished sensory perceptions, drooping eyelids, swelling, discoloration, and bleb formation.  In more serious cases, respiratory problems developed, requiring medical treatment for asphyxiation.  No known human deaths have resulted from brown Treesnake bites.

Approximately 1 in 1,000 emergency room visits in Guam are for treatment of brown Treesnake bites.  Although no medically serious bites on adult humans have been recorded, the potential for serious incidents involving small children exists, especially with a large snake.  The snakes also seem to seek out small children and have been found on more than one occasion to select an infant even when the child is sleeping between both parents.  The data shows that snakes consistently attack very small children.  This has been extended to show that snakes also seem cued in to animals giving birth and birds laying clutches, which has instigated research into possible instinctual tendencies at work in the snake to alert them to vulnerable prey situations.

Precautions and Emergency Response

Photograph of brown tree snake in a defensive posture.' USGS photo by G.H. Rodda.If you are a parent living on Guam or considering visiting Guam with small children, note that there are certain precautions that should be taken.  While the brown tree snake bite is seldom serious to adults, children may be particularly susceptible to the venom.  If your child is bitten, seek medical attention, especially if symptoms such as difficulty in breathing, lethargy, or poor motor coordination are evident.  There is no specific antitoxin for the brown Treesnake, but standard emergency room procedures and treatment of medical signs and symptoms are adequate and the recommended protocol for dealing with brown Treesnake bites.  All serious bites should be reported to Guam Public Health authorities or medical personnel.

PRECAUTIONS TO SAFEGUARD SMALL CHILDREN:

1. Keep snakes out of houses and away from children
2. Seal openings around windows, plumbing fixtures, vents, and air conditioners
3. Avoid leaving children unattended in unprotected places

VICTIMS MOST AT RISK FROM THE BROWN Treesnake:

1. Young children under 3 years of age
2. Victim constricted by snake
3. Bite involves a large snake (larger than 1.3 m)
4. Evidence exists of multiple bites or chewing
5. Victim displays signs of: drooping eyelids, poor muscle tone or coordination, depressed heart rate, respiratory distress, prominent swelling or discoloration beyond the actual site of the bite

The symptoms and signs seen in victims bitten by the brown Treesnake exhibit considerable variation.  Persons meeting some or all of the above criteria for serious bites should be observed closely for at least 6 hours after the bite to allow immediate response to pronounced reactions.

 

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