Insect stings and bites Diagnosis

  • Diagnosis

    A variety of insects sting or bite humans. Stings or bites from bees, yellow jackets, wasps, hornets, ants, spiders, and ticks are common, and are usually harmless. However, allergic reactions to stings or bites can be serious. Figure 01. For most people, bug bites or stings are not a major event. They may hurt for a little while and leave a swollen, red mark that eventually goes away. But for about 3% of the population, bug bites or stings can be quite serious -- even fatal. Some people are highly allergic to substances contained in the venom of certain insects — particularly that of bees, wasps, hornets, and fire ants — and may require emergency treatment. Others may acquire infections secondary to insect stings or bites or pick up an infection transmitted by an insect such as a tick.

    Click to enlarge: Brown recluse spider

    Figure 01. Brown recluse spider

    After an insect sting or bite, part of the immune system overreacts to substances in an insect’s venom. When the immune system encounters foreign proteins from an insect’s venom (allergens), it releases histamine and other chemicals that cause inflammation of surrounding tissues. Red welts (hives) may show up on the skin. Sometimes deeper tissues are affected. In highly sensitive individuals, this type of allergic reaction can cause a reaction called anaphylactic shock, in which the airways becomes constricted, breathing becomes difficult, and blood pressure drops.

    Some ticks harbor infections that can be transmitted to humans Figure 02. Ticks survive by feeding on the blood of animals and humans. Some ticks carry organisms that cause illnesses such as Rocky Mountain spotted fever (carried by wood ticks and dog ticks), Lyme disease (carried by deer ticks), ehrlichiosis (rare, often mild with few symptoms, but sometimes severe; carried by deer ticks and Lone Star ticks), and babesiosis (a rare, potentially fatal disease for humans, carried by deer ticks). It usually takes hours or even days of attachment for an infectious agent to be passed from the tick’s saliva to the human bloodstream.

    Click to enlarge: Tick

    Figure 02. Tick

    Insect stings or bites may cause a short-term skin reaction or trigger a more widespread allergic response Figure 03. In the majority of cases, an insect sting or bite hurts for a little while. There may even be some swelling and redness at the site that usually goes way within a few hours. In a hypersensitive person, however, hives can appear within minutes of a sting or bite. A large (more than 10 centimeters or more in diameter), red, painful swelling lasting anywhere from two to five days might also occur. A person who is extremely sensitive could develop swelling in the tongue, eyes, or throat, and have a hard time breathing. Nausea, faintness, heartbeat abnormalities, and loss of consciousness are other serious consequences.

    Tick infections produce flu-like symptoms, including fever, chills, fatigue, muscle pain, and headaches. Body aches and pains, fever, and headaches are traits of many illnesses. Because tick bites are not painful and typically happen in obscure places like behind the ears, on the scalp, or in the groin area, people may not even realize that they have been bitten, and attribute their symptoms to other things.

    While rash is a common feature of tick infections, not every case produces one. Rocky Mountain spotted fever sometimes brings out a rash that starts as flat, pink spots on the wrists and ankles and spreads to the palms and soles of the feet and eventually to the trunk. A tell-tale sign of Lyme disease is the so-called bull’s eye rash (a large round red spot with a white center) around the bite site that accompanies flu-like symptoms. Ehrlichiosis and babesiosis may not involve the skin; these tend to produce severe headaches and nausea and vomiting.

    Symptoms of The Most Common Tick Infections Disease Carried by... Symptoms Rocky Mountain

    Spotted Fever
    Wood ticks Fever, headache, rash within a few days of infection.
    Dog ticks Lyme Disease Deer ticks Bull’s eye rash, flu-like symptoms (fever, chills, fatigue, muscle pain), stiff neck, sore throat within a month of infection. Ehrlichiosis Deer ticks Fever, severe headache, chills, body aches and pains, nausea and vomiting within 2 weeks of infection. Lone Star ticks Babesiosis Deer ticks Fever with night sweats, nausea, headache within six weeks of infection.
    Click to enlarge: Bite from a tick

    Figure 03. Bite from a tick

    Geography plays a role in insect stings and bites Figure 04Figure 05. Despite the name, just 2% of people who get Rocky Mountain spotted fever live in the Rocky Mountain area. The illness has been reported in every state in the country. Lyme disease, named after the Connecticut town (Old Lyme) in which it was first discovered, affects New Englanders mostly. However, the illness has been reported up and down the east coast as well as in the mid-Atlantic and midwestern regions of the country. One type of ehrlichiosis is prevalent in the same places as Lyme disease, and the other shows up in southeastern states. Babesiosis rears its head in northeastern vacation spots such as Nantucket, Martha’s Vineyard, and Fire Island. Scorpions reside in Florida and in the southwest. The southern states are infested with fire ants, and colonies have been seen in New Mexico, Arizona, and California as well. Bees and other flying insects are prevalent throughout the United States.

    Time of year is another factor in insect stings and bites. April through September is prime tick season. Stings from bees, yellow jackets, hornets, wasps, and ants more commonly occur during summer months.

    Click to enlarge: Distribution map for fire ants within the US

    Figure 04. Distribution map for fire ants within the US

    Click to enlarge: Distrubution map for Lyme disease

    Figure 05. Distrubution map for Lyme disease

    Allergy skin tests can reveal precisely which insects you are allergic to. If you have had a serious or body-wide reaction to an insect sting or bite, you might want to consider allergy skin testing. This is especially true for the stinging insects, bees, wasps, yellow jackets, hornets, and ants. For such a test, your doctor or allergist will dilute an extract of insect venom and inject a small amount into your skin. If you are allergic, you will develop redness and swelling around the injection site within 20 minutes. You can then receive a series of injections (venom vaccines) to immunize you to prevent reactions in the future. If you are not allergic, no redness or swelling will occur.

    Your doctor may be able to identify which type of insect stung or bit you by the type of wound or skin rash you have. A sting from a fire ant can produce hives almost immediately in some people, and a pustule usually develops at the site within a day or so. Spider bites sometimes result in skin ulcerations that are slow to heal and lead to scarring. If you notice any blue or purple surrounding a bite, it is possible that a black widow or brown recluse spider was the culprit. Stings from bees and other flying insects typically create swelling and redness -- sometimes across a very large area. And in some cases, a tick bite will cause a rash.

    Avoid nests to prevent ant, bee, wasp, yellow jacket, and hornet stings. If you are allergic to bees or other stinging insects, be on the lookout for nesting insects and do not to disturb them. Hornets usually nest in trees, and wasps often choose the eaves of a house or under an overhang for nesting. Yellow jackets have an affinity for old logs and dirt piles. They are drawn to outdoor venues where food is served, such as hot dog stands and picnics, so be careful when you eat outside. When using public trash cans, look before you toss. Yellow jackets could be buzzing around them.

    When you are outside, use protective clothing and screens to create a barrier against bugs.

    • Wear shoes that cover your entire foot (not sandals) to avoid stepping on a bee or picking up a tick
    • When walking through woods or tall grasses, wear long-sleeved shirts and long pants
    • Tuck your shirt in and pull your socks up around the bottom of your pant legs to deny ticks entry
    • Wear gloves when collecting wood for a fire
    • Use screens when you open the windows and doors of your house on nice days
    • Keep in mind that perfumes and deodorants may attract insects. You may want to avoid using them if you are planning on spending the day outdoors

    Apply insect repellant before doing outside work and activities. Repellants that contain DEET or permethrin will deter most insects and ticks. Although used safely by millions each year, a very small number of seizures and other neurological problems have been reported. Follow directions for application carefully.

    • Apply repellant to your clothes and any exposed skin areas (avoiding cuts, wounds, and other irritated areas)
    • Take special care when applying insect repellant to your face, and try to avoid getting it in your eyes and mouth
    • Do not spray your face; spray your hands and use them to apply the repellant to your face
    • Put insect repellant on your kids rather than having them do it themselves. Avoid placing repellant on a child’s fingers, which are likely to have contact with eyes and mouth
    • When you return home for the day, shower or bathe to wash the repellant off your skin

    There are other repellents on the market that do not contain DEET but are effective at keeping bugs away. The main ingredient in these products is usually citronella, a pungent oil that many insects are repelled by.

    If you are at high risk for Lyme disease, you may want to consider the Lyme disease vaccine. If you live in an area where Lyme disease is prevalent and you are outdoors frequently for extended periods of time, you are considered to be at high risk. Under these circumstances, your doctor may recommend the newly approved Lyme disease vaccine (Limerix) if you are between the ages of 15 and 70. However, the vaccine is only 76% effective, so you need to stay on guard against tick bites. Also, the vaccine has not been available long enough to demonstrate long-term safety and efficacy.

    Spiders tend to live in places that are left undisturbed. Elimating cluttered areas in basements, closets, attics, and other areas may help remove spiders. Shake out towels, sheets, clothing and shoes that have not been used for a long time before using them again. Get rid of trash, old boxes, piles of lumber, old clothing, and other unwanted items from around your home. Do not handle firewood without gloves. Install screens on doors and windows to prevent spiders and other insects from entering your home. Seal cracks and crevices where spiders might crawl through.

  • Prevention and Screening

    Avoid nests to prevent ant, bee, wasp, yellow jacket, and hornet stings. If you are allergic to bees or other stinging insects, be on the lookout for nesting insects and do not to disturb them. Hornets usually nest in trees, and wasps often choose the eaves of a house or under an overhang for nesting. Yellow jackets have an affinity for old logs and dirt piles. They are drawn to outdoor venues where food is served, such as hot dog stands and picnics, so be careful when you eat outside. When using public trash cans, look before you toss. Yellow jackets could be buzzing around them.

    When you are outside, use protective clothing and screens to create a barrier against bugs.

    • Wear shoes that cover your entire foot (not sandals) to avoid stepping on a bee or picking up a tick
    • When walking through woods or tall grasses, wear long-sleeved shirts and long pants
    • Tuck your shirt in and pull your socks up around the bottom of your pant legs to deny ticks entry
    • Wear gloves when collecting wood for a fire
    • Use screens when you open the windows and doors of your house on nice days
    • Keep in mind that perfumes and deodorants may attract insects. You may want to avoid using them if you are planning on spending the day outdoors

    Apply insect repellant before doing outside work and activities. Repellants that contain DEET or permethrin will deter most insects and ticks. Although used safely by millions each year, a very small number of seizures and other neurological problems have been reported. Follow directions for application carefully.

    • Apply repellant to your clothes and any exposed skin areas (avoiding cuts, wounds, and other irritated areas)
    • Take special care when applying insect repellant to your face, and try to avoid getting it in your eyes and mouth
    • Do not spray your face; spray your hands and use them to apply the repellant to your face
    • Put insect repellant on your kids rather than having them do it themselves. Avoid placing repellant on a child’s fingers, which are likely to have contact with eyes and mouth
    • When you return home for the day, shower or bathe to wash the repellant off your skin

    There are other repellents on the market that do not contain DEET but are effective at keeping bugs away. The main ingredient in these products is usually citronella, a pungent oil that many insects are repelled by.

    If you are at high risk for Lyme disease, you may want to consider the Lyme disease vaccine. If you live in an area where Lyme disease is prevalent and you are outdoors frequently for extended periods of time, you are considered to be at high risk. Under these circumstances, your doctor may recommend the newly approved Lyme disease vaccine (Limerix) if you are between the ages of 15 and 70. However, the vaccine is only 76% effective, so you need to stay on guard against tick bites. Also, the vaccine has not been available long enough to demonstrate long-term safety and efficacy.

    Spiders tend to live in places that are left undisturbed. Elimating cluttered areas in basements, closets, attics, and other areas may help remove spiders. Shake out towels, sheets, clothing and shoes that have not been used for a long time before using them again. Get rid of trash, old boxes, piles of lumber, old clothing, and other unwanted items from around your home. Do not handle firewood without gloves. Install screens on doors and windows to prevent spiders and other insects from entering your home. Seal cracks and crevices where spiders might crawl through.

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