Risk Management Series: Chiggers and the Dreaded Two-Week Itch

Chiggers, also known as "red bugs," are larvae of mites belonging to the Trombiculids family of insects. Trombiculids are predatory mites related to ticks and spiders. The adults are known as harvest or scrub mites. They feed on insect eggs and small invertebrates in soil or decaying wood. Depending upon the species, it takes fifty to seventy days for the mite to develop from egg to larva to nymph to adult.

Trombiculids are found in temperate and tropical areas worldwide--according to some of our students, a large population of these mite larvae live in North Carolina. The Trombiculids larvae are parasites that wait on the ground and/or on low-growing vegetation near where they hatched. When an animal passes by, the larvae leap on it and search around for a feasible feeding spot. Notably, they do not have to search far on you or I for a suitable place. For me it is anywhere and everywhere--I must have sweet fluids just under my skin.

The larva generally prefers a skin pore or hair follicle. It inserts its mouth parts and injects a digestive enzyme into its host. The digestive fluid allows the parasite to feed on a resulting liquid mixture of lymph, dissolved skin tissue and a few stray blood cells--yup, sweet stuff. A chigger normally feeds for two or three days on the protein-rich liquid, then drops off to molt into the nymph stage. A localized rash or swelling called trombidiosis continues to itch for up to two weeks, even if the chigger was only attached for a few hours. The itch is intense and I found the only way to minimize this is a very hot shower which mixes itch, pain and pleasure. Actually, the hot water (just under scalding) triggers anti-histamines that naturally and temporarily diminish the intensity of the itch just long enough for some much needed rest.

Humans are incidental hosts, chiggers are more frequently found on birds, lizards, and rodents. Chiggers prefer to attach on parts of the body where clothing fits tightly or where the flesh is thin, tender, or wrinkled. For this reason, chiggers locate in such areas as the ankles, waistline, knees, or armpits. Some people exhibit an allergic reaction to the fluid which may result in severe swelling, itching, and fever. People mistakenly believe that chiggers embed themselves in the skin or that the welts contain chiggers. Often scratching at the welt results in secondary infection.

Chiggers are easily removed from the skin by taking a hot bath or shower and lathering with soap several times. I have even shaved my legs in severe infestations. The bath will kill attached chiggers and others which are not attached. Since symptoms of contact may not appear for several hours, it is not always possible to completely prevent welts caused by chigger bites. Antiseptic should be applied to all welts which do appear. Temporary relief of itching may be achieved with nonprescription local anesthetics available at most drug stores. Studies have shown that meat tenderizer, rubbed into the welt, will alleviate itching.

If you are going into areas suspected of being infested with chiggers, wear protective clothing and use repellents. Dusting sulfur is often used as a repellent. Repellents should be applied to legs, ankles, cuffs, waist, and sleeves by clothing application or directly to the body or clothing as directed by the label.

The Risk at Earth Connection? Well, we have a few Chiggers in the fielded area, of that I can attest from personal experience. So, yes, we have them, but not as bad as they could be. Prepare yourself for class with repellents.

Source: Chiggers, ENY-212, University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS), Accessed on 28 July 2007 at http://edis.ifas.ufl.edu/IG085