Introduction Insects, scorpions, spiders and ticks are members of a group of animals known as arthropods. Several species can sting or bite, transmit disease organisms, cause serious allergic reactions and are considered harmful to humans. Bees, wasps and hornets can also be the cause of injury without stinging. When accidentally disturbed or encountered, these insects can create so much excitement that people often panic and become careless while trying to escape. Individuals have been known to jump from ladders and scaffolding, abandon running machinery (bulldozers, tractors, chainsaws, etc.), throw tools and even loose control of their automobiles. The injuries sustained while trying to avoid a sting can be severe to fatal. This section describes those harmful arthropods that are encountered during everyday activities. Information about their habits has been provided and should be helpful to people who work and recreate outdoors. The medically important arthropods are found in all sorts of unexpected places. Utility workers, tree surgeons, painters and others may find themselves high above the ground when wasps appear. Children are likely to be stung or bitten while playing outside in yards, parks or school grounds. Servicemen and repairmen who crawl under buildings often encounter spiders and scorpions. Campers and hikers may find themselves far away from medical assistance when danger strikes. Avoidance is a key step in preventing bites and stings. This section has been prepared to familiarize you with the most common, medically important arthropods and where they live. Be alert and keep a watchful eye and remember most arthropods are beneficial and only attack when threatened. Always consult with your physician or health care professional for the most up-to-date treatments of bites and stings. Allergic Reactions Venom and saliva of arthropods can cause allergic reactions in humans. The severity of reactions varies and depends on the nature of the venom/saliva and the individual’s sensitivity to it. Most allergic reactions to stings and bites are brought about by the body’s own immune system. Antibodies are produced to attack the intruding allergen. The antibody most closely associated with allergies is immunoglobulin E (IgE). We all possess IgE antibodies as part of our immune systems; however, some individuals appear to produce larger quantities. When these IgE antibodies collide with the allergens, chemical substances are released one of which, is histamine. Histamine can cause a number of reactions in humans. These reactions may affect the circulatory, respiratory and other body systems. The reactions vary in severity depending on the amount of histamine released. Persons whose immune systems are producing large quantities of IgE antibodies will exhibit more intense allergic reactions and are considered to be hypersensitive. Until first exposed to an allergen, the body has not developed any allergen-specific IgE antibodies; therefore, the first exposure to a venom is usually not life threatening. After the body has been exposed to a particular allergen, it becomes sensitized to it and future stings may result in similar reactions or even more severe reactions. The venom of honey bees and certain wasps contains histamine. Therefore, when histamine is injected directly into the body, reactions can occur immediately and are not antibody mediated as described above. Honey bee stings and those of some wasps (social and solitary) contain histamine. Fortunately only a small percentage of the human population is hypersensitive. The typical response to a single sting is intense pain and burning for 10-15 minutes. A weal often forms soon after the sting (Figure 182). Some local swelling around the sting site may occur. Generally, after a day or so only an itchy spot remains at the sting site.
Non-hypersensitive individuals receiving many stings often experience the same symptoms as with a single sting except the pain and swelling are more intense and last for longer periods. These reactions are referred to as large local reactions but are not considered life threatening and require no medical attention (Figure 183). The reactions of medical concern are referred to as systemic or generalized reactions. Systemic reactions can be classified as cutaneous, vascular, or respiratory. Cutaneous reactions involve only the skin and consist of rashes, itchiness, swellings, hives and general reddening. Vascular reactions may lead to dizziness, fainting and unconsciousness. Respiratory reactions consist of swellings and/or massive buildups of fluids in the respiratory system. This causes difficulty in breathing, sneezing, tightness in the throat and chest or frothing from the mouth. Respiratory reactions are terrifying to the victim because he or she perceives they are suffocating. Other reactions often involve the gastrointestinal tract and result in nausea, vomiting, diarrhea, headache, chills or fever, weakness and a feeling of impending fear. Reactions involving the vascular and respiratory systems are of major medical concern. The inability to obtain air or a very low or absent blood pressure means oxygen deprivation is occurring to the brain that may result in possible death. Reactions, which cause congestion in the heart, brain or lungs, are anaphylactic in nature and are very serious. Hypersensitive persons can be desensitized by receiving injections of venom preparations from the arthropod species to which they are allergic. The injections are gradually increased in strength until the patient can tolerate a few stings without having an allergic reaction. This procedure is known as immunotherapy and is done by a physician (allergist). Immunotherapy is a complicated and lengthy procedure and the patient will require numerous injections. The entire program must be completed as prescribed by the physician. Recent studies indicate venom immunotherapy is highly effective in reducing the reoccurrence of a systemic reaction and is recommended for hypersensitive people. However, people who have undergone immunotherapy should continue to avoid stings and be aware that they may be one of the unfortunate few who may react to a sting at some later date. Insect sting kits are
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Forest Pests: Insects, Diseases & Other Damage Agents |
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