Stung by a Bee

Bee sting allergy is an important cause of severe allergic reactions worldwide. Honeybees, bumblebees, wasps, hornets, and yellow jackets each possess a stinger that is used to introduce venom into the victim. A recent study showed that the yellow jacket species Vespula maculofrons, which tends to live in large underground nests, is more likely to cause a severe reaction than is the species Vespula germania. However, it is impossible to predict which victims will suffer severe reactions, so one must always be prepared for the worst.

The honeybee carries a doubly barbed stinger attached to a venom sac that pumps venom into the victim. When the bee attempts to escape after the sting, the stinger and sac remain in the victim and may continue to inject venom. Wasps, yellow jackets, hornets, and bumblebees can sting their victims multiple times.

If a victim suffers a severe allergic reaction to an insect bite or sting, it may be necessary to administer epinephrine (adrenaline). This is injected subcutaneously (just under the skin). The drug is available in allergy kits, such as EpiPen and EpiPen Jr. A new product that allows second dose administration of epinephrine for an allergic reaction is the Twinject auto-injector, that comes in two dosage sizes: 0.3 mg per dose or 0.15 mg per dose. In addition to epinephrine, the stung victim may benefit by taking an antihistamine (e.g., diphenhydramine [Benadryl]). If the stinger (and venom sac) is still felt to be present, it should be removed as quickly as possible, using the most convenient method (scraping, tweezer) available.

If a person is stung or bitten by an insect and shows any sign of a severe allergic reaction (e.g., difficulty breathing, wheezing, facial swelling, tongue thickness, weakness), he or she should seek immediate medical attention.

Tags: bee sting, wasp, epinephrine, medical, physician, health, wilderness medicine, outdoor medicine, healthline

photo by Paul Auerbach

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Shelf Life of Antivenom

A reader asks: "What's the shelf life of antivenom and does it have to be refrigerated? Can I take it hiking?" This is a common and important question. To answer the first question, for the newest North American antivenom product, CroFab™ [Crotalidae Polyvalent Immune Fab (Ovine)], used for treatment of pit viper (e.g., rattlesnake) bites, the antivenom is provided in vials that contain the antivenom, which is mostly composed of fragile proteins, in lyophilized ("freeze-dried") form. The freeze-dried product has a shelf life of 2 to 3 years when stored protected from light and in a cool place (at a temperature of 2 to 8 degrees C, or 36 to 48 degrees F). To administer the antivenom to a human, the health care provider mixes ("reconstitutes") it with liquid, so that it can be injected into a vein of the recipient. Once it is reconstituted, it must be used within a few hours or it loses its effectiveness.

The second question is more important. Should you carry it with you when hiking, presumably for administration in the field in the event of a snake bite? That question is sometimes asked by medical professionals. The answer to them is that it depends on the snakes that might be encountered, which antivenom they propose to carry, the situation in which it will be deployed, how far they will be from advanced medical care, and their qualifications as health care providers. The traditional answer has always been "No": that is, administering antivenom in the field is considered too dangerous, because there has always been a high risk for a serious (potentially fatal) allergic reaction to antivenom, which is composed of animal (usually horse) serum. The newer antivenom products, like CroFab™, while more pure than the previous products, still carry with them the risk for an allergic reaction when given to a person. So, a doctor must balance the benefit of the antivenom against the risk for the allergic, or other adverse, reaction. The only circumstances of which I am aware when antivenin has been carried to be administered in the field have been where the expedition was traveling into extremely venomous snake country quite far from help or the ability to rapidly evacuate a victim, trained doctors were present to administer the antivenom and to treat any adverse reaction, proper medical equipment was carried, and persons experienced in identification of indigenous medical snakes and snake bite treatment were present. Even then, it is done with trepidation, because the mantra is always, "First, do no harm," and a bad allergic reaction to antivenom could easily be much worse than the effects of a snake's venom.

So, for a layperson, the answer remains, "No - do not take antivenom with you on a hike." However, always have a plan for what you will do in the event that you or someone with you becomes bitten by a venomous snake. This generally means a plan for rapid transport to a hospital where antivenom can be given, if necessary, by trained medical professionals.

Tags: snake bite, snakebite, antivenom, medical, physician, health, wilderness medicine, outdoor medicine, healthline

photo by Sherman Minton

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Insights on Repellents

At Tropical Medicine 101, we had a wonderful lecture about insect repellents from Dr. Scott Carroll, a biologist from the University of California, Davis who studies insect behavior and evolution. One of the more interesting points he made is the fact that "lemon eucalyptus," which is marketed as a repellent and felt to be as effective as 7.5% DEET, is actually not from eucalyptus, but is actually a product from the lemon-scented gum tree Corymbia citriodora (pictured here).
The product is water-distilled from the leaves, and the repellent is found in the spent fraction as para-menthane-3,8-diol (PMD). Of particular note, true eucalyptus oil does not work as an insect repellent.

Other repellents that are effective contain DEET, or N, N-diethyl-m-toluamide, which is the active ingredient that is most widely used in commercially available insect repellents. A concentration of 20 to 30% is sufficient. Picaridin (KBR 3023 or Bayrepel), also in a 20% concentration, is an excellent repellent, as is 20% IR 3535 (sold as Avon Skin So Soft BUG GUARD PLUS IR3535® EXPEDITION™ Insect Repellent Aerosol). Picaridin and IR 3535 (ethyl butylacetylaminopropionate) may have more favorable safety profiles compared to DEET, but all three are still highly recommended.

Tags: insect repellent, DEET, picaridin, IR 3535, lemon eucalyptus, medical, physician, health, wilderness medicine, outdoor medicine, healthline

photo of Scott Carroll by Jenella Loye

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Contact Lens Solution

Bausch & Lomb recently had a recall on its ReNu multi-purpose contact lens solution, because it was linked to serious eye infections caused by fungus of the genus Fusarium. A few researchers believe that the multi-purpose solutions in general are more prone to transmitting infection, for reasons that have yet to be clearly determined.

Regardless of whether or not multi-purpose solutions are riskier than single-purpose solutions, outdoor enthusiasts should note that contact lenses may be more difficult to manage in a wilderness environment for the following reasons:

1) Should a contact lens become displaced (e.g., fall out of the eye), it may be more easily lost than eyeglasses.
2) Contact lens solution can degrade or become contaminated by exposure to extreme temperatures, dehydration, or passing over dust and dirt that can accumulate on the threads of bottle caps.
3) Handling contact lenses with dirty hands can introduce bacteria and fungi to lens or tissues of the eyes.
4) It may not be easy to change out contact lenses quickly if needed for a different refraction or environmental (e.g., sun or wind exposure) condition.
5) Once an eye becomes infected, contact lenses must be removed. They should not be re-used if removed because of infection.

For these reasons, it’s important to carry at least one, and preferably two, pairs of eyeglasses. If you need reading glasses, carry these as well. Also, be sure that you have sunglasses that block out as much ultraviolet light as possible. Include side shields if you are going to be at high altitude, on snowfields, on the water’s surface, or traversing other highly reflective terrain, such as bright sand.

Tags: contact lens, contact lens solution , wilderness medicine, outdoor medicine, healthline

photo by Paul Auerbach

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Questions About Snake Bite

A reader asks: “Do all hospitals have antivenom serums? Also, is it true that sucking out the venom from the wound of a snake bite prevents poisoning?”

With regard to hospitals in North America, some hospitals stock antivenom products in their pharmacies, but most do not. The hospitals that tend to have the antivenoms are those in locations where snake bites are more commonly seen, such as the southwestern U.S. On occasion, antivenom is stored in locations (e.g., zoos) where snakes are housed for display. In the event that someone is bitten by a venomous snake and requires antivenom, the treating physician can locate antivenom by calling a regional poison control center for assistance. In the United States, assistance in finding antivenom can be obtained 24 hours a day from the University of Arizona Poison and Drug Information Center (telephone: 520-626-6016).

There is no good evidence that sucking out the venom from the wound of a snake bite prevents poisoning. This includes using suction from one’s mouth or a mechanical device. Although many items, such as rubber suction cups, plastic extraction devices, electrical stun guns, and other gadgets have been recommended at one time or another to either remove venom or to neutralize its effects, none of these has been proven to be of any benefit. Furthermore, if their application causes the victim to delay in seeking definitive medical care (e.g., antivenom if needed), they can actually be harmful. The current recommendations from snake bite experts do not advocate using suction as a method to minimize or prevent the effects of a snake bite.

Tags: snake bite, snakebite, antivenom, medical, physician, health, wilderness medicine, outdoor medicine, healthline

photo by Sherman Minton

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Tropical Medicine 101

I just returned from a week in Panajachel, Guatemala, where I served as one of the faculty members teaching at a continuing medical education (CME) program entitled “Tropical Medicine 101.” The course is the brainchild of Dr. Gil Mobley, who has participated in extraordinary work with the the Hospitalito Atitlan and the Lake Atitlan Medical Project (LAMP) for many years.

In describing this experience, it is difficult to know where to begin, so I will use this particular post to simply describe the setting, and use future posts to go into greater detail about some of what we learned, both medically and with regard to the remarkable people of the immediate region.

Lake Atitlan sits in the western highlands of Guatemala, the result of a volcanic explosion some 85,000 years ago that created a huge caldera. It is a magnificent place, tropical in its jungle foliage, yet temperate in climate. The enormous lake, one of the largest in the world and of the order of Lake Tahoe and Crater Lake, is surrounded by volcanoes, all currently dormant. The conference was held at the Hotel Atitlan in Panajachel (“Pana”), a bustling town maintained by colorful and industrious locals. However, the current political calm of the city is a relatively recent phenomenon, as we learned in an incredible evening presentation by Bonnie Dilger, author of the book Blood in the Cornfields. I will write more about this in a future post.

The faculty members were phenomenal, and I look forward to highlighting some of what I learned. This was wilderness medicine at its best, because it took into account not only the clinical aspects of what we must do, but also the social context in which it should be done. The tour of the temporary hospital that serves the people of the lake region as they await a replacement facility for their hospital that was devastated in the mudslides last year, and a walk through the camp in which the families displaced by that tragedy left deep and life-changing impressions on many of the participants, including me.

Tags: Tropical Medicine 101, Guatemala, travel medicine, medical, physician, health, wilderness medicine, outdoor medicine, healthline

photo by Paul Auerbach

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Indian National Snakebite Conference

My good friend Bob Norris, M.D., who is Chief of Emergency Medicine at Stanford and an internationally-recognized authority on venomous snake bites, recently participated in the Indian National Snakebite Conference. This was the first such conference to be held in India. The leading experts in India, plus some international experts, joined herpetologists, statisticians, and researchers to provide advice about improving current snakebite management and research in India.

Ian Simpson of the World Health Organization (WHO) Snakebite Treatment Group reports that the Conference was a fruitful event, as the participants developed an evidence-based protocol for both first aid and treatment of venomous snake bites, which was heretofore lacking in a country that witnesses a large number of bites with significant morbidity (serious medical effects) and mortality (death). The protocol stresses reassurance, immobilization of the bitten body part without compression or tourniquets, and prompt transport to a location where antivenom can be administered. It was also recommended that adrenalin (epinephrine) be readily available for intramuscular injection in the event of an allergic reaction to antivenom.

For a country with one billion people and the highest snakebite mortality in the world, the conference was a breakthrough. The government of India and the WHO are reviewing the protocol for implementation in India. Literature will be sent to hospitals with treatment protocols, a booklet on first aid techniques, a booklet for doctors on "Snakes of Medical Significance," and posters to aid in snake identification and first aid.

Tags: snake bite, snakebite, Bob Norris, India, Ian Simpson, wilderness medicine, outdoor medicine, healthline

photo of Bob Norris with king cobra by Ian Simpson

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A Global Partnership for Snake Bite

In Volume 3, Issue 6 (June 2006) issue of the Public Library of Science (PLOS) Medicine, which is a peer-reviewed, open-access journal, there was an article entitled “Confronting the Neglected Problem of Snake Bite Envenoming: The Need for a Global Partnership.” The authors, led by Jose Maria Gutierrez, pointed out that poisoning from snake bites is an international problem that requires more attention and standards of first aid and medical care, particularly in Africa, Asia, Oceania, and Latin America.

The current situation is that there is not very reliable reporting of snake bites, but from what is known, it appears that the high death rates are related to scarcity of antivenoms, poor health services, and lack of swift access to health centers. This is particularly the case with children, who are common victims of snake bites.

The authors point out that the species causing the greatest numbers of bites and fatalities are Echis species (saw-scaled vipers) in northern Africa, Bothrops species (lance-headed vipers) in Central and South America, and Naja species (cobras) and Bungarus species (kraits) in Asia. The photos here are from the original article, and depict (A) saw-scaled viper from Nigeria; (B) cobra from Sri Lanka; and (c) terciopelo from Costa Rica.

At the current time, horse- or sheep-derived antivenom administered intravenously is the only specific treatment for snake bite poisoning. This is often effective at saving life and limb, but frequently at the cost of an allergic reaction.

Finally, the authors call for a global partnership in order to foster international collaboration that will lead to better epidemiological information about all aspects of snake bite, to promote the development of improved antivenoms, and to provide antivenoms in regions where they are not currently available.

Tags: snake bite, snakebite, antivenom,wilderness medicine, outdoor medicine, healthline

photos A and B by David Warrell; photo C by Mahmood Sasa

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