Insect Bites

Symptoms

DEFINITION

• Itching, pain, or swelling from an insect bite
• Itchy Insect Bites: Bites of mosquitoes, chiggers (harvest mites), fleas, and bedbugs usually cause itchy, red bumps
• Painful Insect Bites: Bites of horseflies, black flies, deer flies, gnats, harvester ants, blister beetles, and centipedes usually cause a painful, red bump. Within a few hours, fire ant bites can change to blisters or pimples

Anaphylaxis

• Anaphylaxis is the medical term for a severe life-threatening allergic reaction.
• Symptoms of anaphylaxis include: feeling faint or passing out, difficulty breathing, swelling of the tongue, hives, wheezing and/or cough. Onset of symptoms is sometimes within seconds and usually within 20 minutes.
• Individuals who have had severe reactions to previous stings should have an anaphylaxis kit (e.g., Ana-Kit, Epi-Pen) and keep it nearby if there is any risk of a sting.
• Anaphylaxis can occur following fire ant stings, but rarely with other insects. It mainly occurs with bee, yellow jacket or wasp stings.

Prevention

• Wear long pants and long-sleeved shirts.
• Avoid being outside when the insect is most active. Many insects that cause itchy bites are most active at sunrise or sunset (e.g., Chiggers, No-See-Ums, Mosquitoes).
• Insect repellents containing DEET also seem to be effective in preventing many itchy insect bites. Read the label carefully.

See More Appropriate Topic (instead of this one) If

• BEE OR YELLOW JACKET STING
• SPIDER BITE
• TICK BITE 
• RASH - LOCALIZED AND CAUSE UNKNOWN, if it does not seem like an insect bite

FIRST AID ADVICE for Anaphylaxis - Epinephrine (pending EMS arrival):

• If the patient has an epinephrine autoinjector, the patient should use it now.
• Use the autoinjector on the upper outer thigh. You may give it through clothing if necessary.

Epinephrine is available in autoinjectors under trade names: Epi-Pen, Epi-Pen Jr, and Twinject. Epi-Pen is a single injection. Twinject has a second injection that can be used if there is no improvement after 5 minutes.

FIRST AID ADVICE for Anaphylaxis - Benadryl (pending EMS arrival):

• Give antihistamine orally NOW if able to swallow.
• Use Benadryl (diphenhydramine; adult dose 50 mg) or any other available antihistamine.

FIRST AID ADVICE for Anaphylactic Shock (pending EMS arrival):

• Lie down with feet elevated.

Should I Call?

WHEN TO CALL YOUR DOCTOR

Care at Home

HOME CARE ADVICE

Treatment for Insect Bites

1. Local Treatment - Itchy Insect Bites (including all mosquito bites)
   • Apply calamine lotion or a baking soda paste.
   • If the itch is severe, use 1% hydrocortisone cream. Apply 4 times a day until the itch is less severe, then switch to calamine lotion.
   • Try applying firm, sharp, direct, steady pressure to the bite for 10 seconds. A fingernail, pen cap, or other object can be used.
2. Oral Antihistamine Medication for Severe Itching: Take an antihistamine by mouth to reduce the itching. Diphenhydramine (Benadryl) is a good choice. The adult dosage of Benadryl is 25-50 mg by mouth and you can take it up to 4 times a day.
   • Do not take antihistamine medications if you have prostate enlargement.
   • Antihistamines may cause sleepiness. Do not drink, drive or operate dangerous machinery while taking antihistamines.
   • An over-the-counter antihistamine that causes less sleepiness is loratadine (e.g., Alavert or Claritin).
   • Read the package instructions thoroughly on all medications that you take.
3. Local Treatment - Painful Insect Bites
   • Rub the bite for 15 to 20 minutes with a cotton ball soaked in a meat tenderizer solution. This will usually relieve the pain (Caution: don't use near the eye).
   • If not available, use a baking soda solution on a cotton ball.
   • If neither is available, apply an ice cube for 20 minutes.
4. Pain Medicines:
   • For pain relief, take acetaminophen, ibuprofen or naproxen.
   • Acetaminophen (e.g., Tylenol):
     • Take 650 mg by mouth every 4-6 hours. Each Regular Strength Tylenol pill has 325 mg of acetaminophen.
     • Another choice is to take 1,000 mg every 8 hours. Each Extra Strength Tylenol pill has 500 mg of acetaminophen.
     • The most you should take each day is 3,000 mg.

   • Ibuprofen (e.g., Motrin, Advil):

     • Take 400 mg by mouth every 6 hours

     • Another choice is to take or 600 mg by mouth every 8 hours.

     • Use the lowest amount that makes your pain feel better.

   • Naproxen (e.g., Aleve)

     • Take 250-500 mg by mouth every 12 hours.

     • Use the lowest amount that makes your pain feel better.

   • Extra Notes

     • Acetaminophen is thought to be safer than ibuprofen or naproxen in people over 65 years old. Acetaminophen is in many OTC and prescription medicines. It might be in more than one medicine that you are taking. You need to be careful and not take an overdose. An overdose can hurt the liver.

     • Before taking any medicine, read all the instructions on the package.

5. Antibiotic Ointment: If the insect bite has a scab on it and the scab looks infected, apply an antibiotic ointment 4 times per day.
   • Cover the scab with a Band-Aid to prevent scratching and spread.
   • Repeat washing the sore, the antibiotic ointment and the Band-Aid 4 times per day until healed.
6. Expected Course: Most insect bites itch or hurt for 1 to 2 days. The swelling may last a week.
7. Call Your Doctor If:
   • Severe pain persists more than 2 hours after pain medicine
   • Infected scab doesn't look better after 48 hours of antibiotic ointment.
   • Bite looks infected (redness, red streaks, increased tenderness)
   • You become worse

West Nile Virus Information

1. Symptoms of WNV:
   • No clinical symptoms: 80% of infections.
   • Mild febrile illness: 20% of infections. Symptoms include fever, headache, body aches, and occasionally a skin rash. These symptoms last 3-6 days and resolve without any treatment (also called WNV fever).
   • Encephalitis or viral meningitis: 0.7% (1 in 150 people) of infections. Symptoms are obvious: high fever, stiff neck, confusion, coma, convulsions, muscle weakness or paralysis. The muscle weakness is often unilateral.
   • Fatal outcome: 10% of those hospitalized
   • Pediatric cases are generally mild. Most deaths and encephalitis occur in people over age 60.
2. Diagnosis of WNV:
   • Mild cases do not need to be diagnosed.
   • Severe cases (with encephalitis and viral meningitis) would all be hospitalized based upon their symptoms, and the disease would be diagnosed by tests on the blood and spinal fluid. These tests are not available for the usual mild infections seen with this virus.
3. Treatment of WNV:
   • No special treatment is needed after a mosquito bite.
   • There is no specific treatment or anti-viral agent for West Nile virus.
   • Patients who require admission are treated supportively with IV fluids, airway management and good nursing care.
   • There is no vaccine available to prevent West Nile Virus in humans.
4. WNV - Spread by Mosquito:
   • The West Nile virus is spread by the bite of a mosquito. The reservoir for the virus is infected birds.
   • Even in an area where West Nile virus has been identified, less than 1% of mosquitoes carry the virus.
   • Transmission is mosquito-to-human.
   • Person-to-person spread does not occur (eg, from kissing, touching, sharing glassware, or sexual intercourse.)
   • Mothers with mosquito bites can continue breast-feeding (CDC 2003).
   • Incubation period: 3-14 days after the mosquito bite.

Preventing Insect Bites

1. Prevention
   • Wear long pants and long-sleeved shirts.
   • Avoid being outside when the insect is most active. Many insects that cause itchy bites are most active at sunrise or sunset (e.g., Chiggers, No-See-Ums, Mosquitoes).
   • Insect repellents containing DEET are effective in preventing many itchy insect bites.
2. DEET - An Insect Repellent
   • DEET is a very effective insect repellent. It also repels ticks.
   • Higher concentrations of DEET do work better - but there appears to be no benefit in using DEET concentrations above 50%. For children and adolescents, the American Academy of Pediatrics recommends a maximum concentration of 30%. Health Canada recommends using a concentration of 5-30% for adults.
   • Apply to exposed areas of skin. Do not apply to eyes, mouth or irritated areas of skin. Do not apply to skin that is covered by clothing.
   • Remember to wash it off with soap and water when you return indoors.
   • DEET can damage clothing made of synthetic fibers, plastics (e.g., eye glasses), and leather.
   • Breastfeeding women may use DEET. No problems have been reported (CDC 2003).
   • Read the label carefully.
3. Picaridin(also called KBR 3023):
   • In 2005 the CDC added Picaridin to its list of recommended insect repellents.
   • Evidence indicates that it works just as well as DEET.
   • It has been used in other countries for years, including Europe, Australia, Latin America and Asia.
   • Read the label carefully.

And remember, contact your doctor if you develop any of the "Call Your Doctor" symptoms.

Photo Example

Source: CDC PHIL

From the CDC's Public Health Image Library (http://phil.cdc.gov), ID#1863, in the public domain.

Photo credit: James Gathany.