What are Chiggers and How do We Treat Them?
  Contributed by: Joel Bakian, Pharm.D. Candidate
                        KU School of Pharmacy

What is a Chigger?
If you have spent some time outdoors you probably have had a run-in with chiggers.  They are typically associated with itching on a person's skin and normally can not be seen by the naked eye.  Chiggers typically live for 7 to 10 weeks anytime from April until the cold fall weather begins.  Their lifecycle begins when the outdoor temperature is regularly above 60°F.  Chiggers are not blood-sucking insects, such as mosquitoes or ticks, and do not burrow into the skin.  Rather, they attach to a persons skin surface, often in a skin pore or hair follicle, and begin to digest the skin cells of that person.     

The chiggers that bite humans and other animals are the larva (or juvenile form) of harvest mites.  Harvest mites are arachnids and are related to ticks and spiders.  There are thousands of species of harvest mites around the world.  The most common species from which chiggers come in Kansas is Eutrombicula alfreddugesi.  The chigger larvae hatch from eggs that adult female mites lay on the ground.  The larvae are red in color and have six legs.  The newly hatched chiggers have one goal - to find a meal!  Chiggers climb up on the blades of grass or weeds and wait for a host.  The host can be a human or any other type of animal.  Women and children are more prone to chigger bites than men because men typically have thicker skin.  Bites can occur anywhere on the body but are most often seen on sites around shoes or where clothing fits tightly such as your ankles, back of knees, armpits, waist or belt line, and wrists.  This is why you often find chiggers in clusters rather than spread out across your skin. 

Itching can begin within several minutes of the chigger attaching to their host even if no bite marks are present.  Most often, itching begins within 3 to 6 hours after biting.  At this time redness and swelling can be seen around the bite.  Eventually an itchy, red bump will develop.  The itching is caused by histamines that are released from the digested skin cells.  Histamines also make your eyes and nose water when you have a cold or allergy.  Chiggers typically feed for 4 consecutive days.  Humans typically scratch the chigger off before feeding is complete.  After feeding is completed, the chigger larvae become adults.  The adult chiggers are also red but have 8 legs instead of 6.  The adults feed on small insects, other mites and eggs.  The adult chiggers DO NOT feed on the skin of humans or animals!

How do I prevent and treat chiggers?
Chiggers are almost invisible to the naked eye so it is hard to keep from being bitten.  Some steps you can take to protect yourself from being bit by chiggers include:

• Wearing long sleeves, pants, and boots
  
• Use of an insect repellant such as DEET or sulfur powder; Never use a flea collar because the chemicals in the collars can burn or irritate human skin
  
• Avoid high grass, tall weeds, and bushes
  
• Shower thoroughly with hot water and soap after being in areas that might be infested with chiggers; This will help remove any chiggers that haven't bitten you and wash them away
  
• Wash clothing that was worn in chigger-infested areas with hot, soapy water;  Hot water is important because

chiggers can survive in cold and warm water

Treating chigger bites is often more difficult than preventing bites.  However, there are several over-the-counter (OTC) products that can help treat chigger bites.  Once bitten, a topical anesthetic is the most effective treatment.  Topical anesthetics such as benzocaine, camphor, menthol, and phenol are the most common.  Your local pharmacist can help recommend a product that contains one of these products.  Here are a few examples:

• Chiggerex® (Benzocaine 5%)
  
• Chigarid® (Camphor 2.8%, Phenol 1.5%, and Menthol 0.1%)