It’s the Little Things That Can Get You: Arthropod Bites and Stings
By Nancy Pietroski, PharmD, WEMT, FAWM, CTH
Summer has arrived with its balmy breezes and BBQs, but for some, the bane of outside existence – insect bites and stings. While most people suffer just annoying local reactions at a bite or sting site, some people are very allergic and may need medications to manage more severe reactions, including life-threatening anaphylaxis. And some bites or stings may do more than just bug you – there are a number of serious infectious diseases that can be carried and delivered in these tiny packages.
In the U.S., more serious diseases from mosquito bites like malaria and yellow fever aren’t around, but there are others diseases like Dengue fever virus, West Nile virus, St. Louis encephalitis, Eastern Equine encephalitis, La Crosse virus, and Jamestown Canyon virus that can cause a host of serious problems. The disease spectrum for these mosquito-borne viruses range from mild symptoms (fever, headache, muscle aches) to severe brain inflammation or shock. There is no specific treatment for these viral diseases – specific symptoms are managed with drugs like antiinflammatory agents or in more severe cases, hospitalization with supportive care may be necessary. As far as prevention, besides avoid getting bitten (which is discussed below), a dengue vaccine is available, but not for use in the U.S. right now.
There is currently no Zika or Chikungunya virus found in the U.S. And there is one important virus that has not been shown to be transmitted by mosquitoes: COVID-19.
It may be startling to learn that there are around 850 species of ticks, all ready to suck your blood, fortunately however, only a handful transmit disease-causing microbes. Global warming has increased the length of the seasons when ticks abound, and their geographic reach is expanding – they can travel on birds who fly around the world, and you can carry them back from a trip on your clothing or suitcases and gear. Closer to home, ticks may be hitching a ride on your animals that go outside; you may be protecting the dog or cat against tick attachment by treating them with tick and flea prevention products, but then the ticks fall off of them and hitch a ride on you.
When a tick attaches to an animal or human, it inserts barbs into the skin, acting sort of like a fish hook. Then it secretes saliva into the blood of its victim that includes an anticoagulant (so blood will flow more easily), an anesthetic (so you don’t feel it while it is sucking your blood), and potentially, an infectious agent. Like ticks, mosquitoes also transmit infectious agents through injection of saliva and blood sucking. Both ticks and mosquitoes that transmit these agents between animals and humans are considered disease vectors.
Lyme disease may be the most familiar tickborne illness in the U.S., but there are a whole host of others that are increasing in prevalence. The table below displays the tick, the most common regions of the U.S. where they reside, and diseases they can potentially cause.
Adapted from: https://www.cdc.gov/ticks/geographicdistribution.html
Symptoms and Treatment of Tickborne Diseases
Many tickborne diseases present with similar symptoms. The diseases below can generally be treated with the oral antibiotic doxycycline, included in the Duration Health formulary and available in Duration Health Med Kits as medically appropriate. In consultation with a physician, doxycycline may be started based on clinical suspicion of the disease, that is, the area of the country where the person lives or has traveled, a history of a tick bite, and the following clinical symptoms. Other tickborne illnesses must be confirmed with a laboratory test before treatment is started. In some cases, these illnesses can progress to more severe disease that necessitates hospitalization with intravenous antibiotics and supportive care.
Localized symptoms (early Lyme disease) include those listed below. Treatment with doxycycline (or some other oral antibiotics, such as amoxicillin) can be started by a doctor in people who present with a rash without a diagnostic lab test having to be conducted first.
• Erythema migrans (EM)—a red ring-like rash, also called a “bullseye” or “target” lesion; this classic rash is not present in all cases
• Flu-like symptoms—malaise, headache, fever, myalgia (muscle pain), arthralgia (joint pain)
• Lymphadenopathy (swollen lymph nodes)
Here's a photo of erythema migrans.
Source: By Hannah Garrison - en:User:Jongarrison, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=4282309
Lyme disease isn't the only thing that causes this "bullseye" rash. A related illness, STARI (southern tick-associated rash illness) also has a similar appearance.
When Lyme spreads to other parts of the body, it is considered disseminated, or late Lyme disease. It can cause rheumatologic problems such as arthritis, cardiac problems such as myocarditis and pericarditis, neurologic complications such as Bell’s palsy, meningitis, or encephalitis, and can also invade the eyes, liver, and spleen. A diagnostic test must be conducted before antibiotic treatment is started for disseminated Lyme disease.
Other Tickborne Diseases
The clinical symptoms of other tickborne illnesses are shown below. Doxycycline is also usually used to treat these diseases.
• Fever, chills, rigors
• Severe headache
• Gastrointestinal symptoms (nausea, vomiting, diarrhea, anorexia)
• Rash (<10%)
• Fever, chills
• Muscle pain
• Gastrointestinal symptoms (nausea, vomiting, diarrhea, anorexia)
• Altered mental status
• Rash (more commonly reported among children)
Rocky Mountain Spotted Fever
Early (1–4 days)
• High fever
• Severe headache
• Edema (swelling) around eyes and on the back of hands
• Gastrointestinal symptoms (nausea, vomiting, anorexia)
Late (5 days and beyond)
• Altered mental status, coma, cerebral edema (swelling)
• Respiratory compromise (pulmonary edema, acute respiratory distress syndrome)
• Necrosis (ie, gangrene) requiring amputation
• Multiorgan system damage (central nervous system, kidney failure)
Because Southern Tick-Associated Rash Illness (STARI) resembles early Lyme disease, treatment with doxycycline is often started based on the presence of a rash. Tularemia can be treated with doxycycline (or other antibiotics), but requires a laboratory test in addition to clinical symptoms. The decision to start treatment must be made in consultation with a doctor.
An unusual allergy to red meat that has been recently reported can develop in some people after a bite from a Lone Star tick (see table above for the regions where this tick lives), called Alpha-gal syndrome. When a tick carrying the alpha-gal sugar molecule injects it via a bite, it can result in an allergic reaction in susceptible people. When they eat red meat, the reaction can range from mild (such as sneezing, runny nose, hives) to life-threatening, such as anaphylaxis. Risk factors include spending alot of time in the outdoors, multiple bites from Lone Star ticks, and a certain immune system dysfunction.
Insect Bite Prevention
Whether you are staying home in the backyard or are traveling this summer, mosquito and tick bite prevention is the key to not contracting one of these potentially serious diseases. Follow these tips to avoid getting bitten and infected.
• Ticks hang out in grassy and wooded areas — avoid these. Know what types of ticks are living in the area where you will be outside.
• Mosquitoes like standing or stagnant water, so discourage breeding grounds by getting rid of containers that hold this.
• Treat clothing with permethrin 0.5%.
• Cover all exposed skin when possible with lightweight clothing, head nets, etc.
• Use an EPA-approved insect repellent including DEET, picaridin, IR3535, Oil of Lemon Eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone. You can find more information about repellent recommendations here.
• Do a careful tick check after you come indoors (and for the dog), including clothing and gear.
Learn to identify the ticks that live in your area and those that you remove. See the recommendations below from the CDC on proper removal. Commercial testing of removed ticks is sometimes advertised, however, this is not recommended by the CDC.
Doxycycline for Lyme disease prevention
The CDC recommends a preventative dose of doxycycline in areas with high rates of Lyme disease when a tick bite has occurred. This includes the following states: CT, DE, DC, MA, MD, ME, MN, NH, NJ, NY, PA, RI, VA, VT, WI, WV.
The idea is to treat people at high risk of contracting Lyme disease as soon as they have been bitten, even if they aren't yet showing any symptoms of the disease.
In order for doxycycline to be taken prophylactically (i.e. before symptoms appear) for a tick bite, the following conditions need to be met:
- Doxycline, a tetracycline antibiotic, cannot be contraindicated. The usual contraindication is an allergy to the drug.
- The tick is Ixodes scapularis (see photo in the table above) in the adult or nymph state.
- The time of tick attachment is approximated to be >36 hours.
- Doxycycline should be started within 72 hours of tick removal (see instructions for removal above).
A single dose of doxycycline 200mg for adults (4.4mg/kg for children weighing less than 45kg/99 pounds) should be taken. Drink with a full glass of water; try to avoid taking it with food or milk as these interfere with the absorption of the drug. It may cause stomach upset. As with any medication, the decision to take doxycycline should be made only with the advice of a physician.
Doxycyline should not be used for prevention of the tickborne illnesses discussed above: anaplasmosis, ehrlichiosis, Rocky Mountain spotted fever.
Other bites and stings
There are many other creatures out there ready to bite or sting you, such as bees, wasps, hornets, blackflies, fire ants, fleas, spiders—the whole arthropod kingdom. It can be hard to avoid getting attacked, so if you are injected with toxic venom, do the following:
• If there is a stinger, remove it and wash with soap and water, apply ice or cool compress, or baking soda to neutralize the venom.
• Local reactions may consist of swelling, redness, itching, pain. Manage with the following over-the-counter medications, included in the Duration Health formulary and available in Duration Health Med Kits.
o Antihistamine such as diphenhydrAMINE (Benadryl®)
o Antiinflammatory agent such as ibuprofen (Motrin®), naproxen (Alleve®)
o Analgesic for pain such as acetaminophen (Tylenol®)
o Topical corticosteroid such as hydrocortisone (e.g., Cortizone®)
o Topical antibiotic (if bite is scratched and gets infected) such as bacitracin/polymyxin (Polysporin®); this can also contain a topical anesthetic
• More serious reactions include hives, lip/eye/throat swelling, difficulty breathing, nausea/vomiting/stomach cramps, dizziness – which may all indicate anaphylaxis, a medical emergency. Administer EPINEPHrine (EpiPen®) if the person is carrying one (they should be if they have had a previous reaction to a sting). Call 911 or go immediately to the nearest ER. The corticosteroid prednisone is also sometimes used to treat severe allergic reaction.
Final advice: do get outside, but don’t let the little things get to you.