What are chiggers?
Chiggers are tiny insects that feed on the human skin. The skin rash caused by chigger bites is commonly mistaken for tick bites or mosquito bites. However, chiggers are a distinct species of insects that belong to the same Arachnid class as spiders and ticks.
Chiggers are mites, but are different from the mites that cause scabies. These tiny insects are also known as red mites or harvest mites. They are a common problem for outdoor explorers. In North America, chiggers are considered relatively harmless. But some of the Asian species of chiggers are known to spread diseases, such as scrub typhus.
What type of an insect is chiggers?
Chiggers are mites that belong to the Trombiculidae family. Mites of this family can be found across the globe, especially in gardens, parks, forests, and areas that are close to water. Chiggers adhere to the grass and parts of plants that are close to the ground. In these habitats, chiggers are barely visible due to their tiny size (about 1/50th of an inch).
When many mites clump together, then the group can be seen with the naked eye. The six-legged immature forms of chiggers (referred to as the larvae) bite humans and other animals. These mites have claws that allow them to attach tightly to their substrate (such as plants, skin, and clothes). After attaching, the mite may travel a short distance till it finds an area that is suitable for it to feed.
Chiggers do not infest human skin chronically. They fall off after some days. Unlike the larval forms, the adult chigger mites are harmless.
Unlike mosquitoes and ticks, chiggers do not consume human blood. Instead, chiggers feed on human skin cells. After attaching to the skin of a human host, chigger mites migrate around the body to find a suitable feeding site. The mite prefers to feed on body areas like skin folds, where the skin is thin. Once a suitable feeding site is found, the chigger mite pierces the skin and injects its saliva.
The saliva of the mite dissolves the skin cells. The chigger mite then forms a feeding tube called stylostome, which allows it to continue feeding on the dissolved human skin cells. The skin on the knees, ankles, groin, armpits and waist are the preferred feeding sites for chiggers. After feeding for a few days, the mite falls off the human host.
Read more on insect bite infection.
Unlike the scabies mite, chiggers do not burrow into the skin or lay eggs underneath the skin. Bite marks appear on areas where the mite has dissolved the skin cells and fed on them. Red bumps appear on the skin areas where the mite had fed before falling off. These bumps are itchy. The itching at the affected skin areas may persist for a few days after the mite has fallen off. The red bumps usually resolve completely within a couple of weeks.
The skin areas where the chiggers have fed is characterized by itchy red bumps. A skin rash made up of many itchy red bumps caused by chigger bites is known as a chiggers rash. The area of the skin surrounding a chigger rash may also show some redness, resembling welts or hives. Based on appearance alone, one may mistake a chigger rash for tick bites, mosquito bites or skin rash caused by poison ivy.
The red bumps on the skin begin to appear about 1-3 hours after the chigger bite. The size of the bumps and the itchiness of the skin increases over the course of the next few days (refer to picture). Scratching the skin to relieve the itch can worsen the chiggers rash by causing tiny tears in the skin. Secondary bacterial infections, mainly caused by the Staphylococci and Streptococci bacteria, may occur in the areas where the skin breaks appear.
Read more on impetigo.
An infected chiggers rash is characterized by redness, swelling, pain, and pus discharge. When the skin infection is restricted to the superficial layer of the skin, the condition is termed as impetigo. If the infection reaches the deeper subcutaneous tissues, then it may cause a serious condition known as cellulitis.
Chigger bites on the skin of the penis cause the summer penile syndrome. This condition is characterized by itching, swelling of the penis, and painful urination. People may mistake this condition for a sexually transmitted disease.
Treatment for Chiggers
In many cases, a chiggers rash may heal on its own within about 2 weeks. Simple home treatment can help in managing the condition. A vigorous skin wash with soap and water will remove any chiggers that are attached to the skin. Skin inflammation caused by chigger bites can be soothed through cold compresses. For the cold compress, a cloth soaked in cold water can be used. Ice should never be applied directly on the skin.
When the symptoms are severe, one should seek medical treatment for chigger rash. The treatment for chiggers is largely aimed at providing symptomatic relief. Calamine lotion can be applied to the affected skin areas. If itching is severe, oral antihistamines may be prescribed. Corticosteroid creams may also be prescribed for treatment of redness, swelling and itching on the skin.
If a secondary bacterial infection is present at the site of chigger rash, then antibiotics are prescribed. For superficial bacterial skin infections, an antibiotic cream may be applied. However, oral antibiotic treatment becomes necessary if the infection affects the deeper tissues (cellulitis).
Fever, severe tenderness, pain and widespread redness of the skin characterize a serious infection. Left untreated, secondary bacterial infections can become life-threatening. Intravenous administration of antibiotics may be necessary in case of very severe infections.
Eradicating chiggers from the environment is a difficult proposition. These mites are found in grassy areas and forests across the globe, where they may play important roles within the ecosystem. But one can easily eradicate these mites from human skin and clothing.
Since chiggers only feed on the skin surface, and do not burrow down into the deeper skin layers, a simple wash with soap and water should be sufficient to remove them from the skin. One should not try to use bleach, alcohol or nail polish remover for removing chiggers from the skin surface. Preventive measures against chiggers include:
- Wearing full pants, long-sleeve shirts and closed shoes when outdoors.
- Washing outdoor clothing thoroughly after soaking in hot water.
- Showering immediately after being outdoors in areas where chiggers are likely to be present.
- Using insect repellents against chiggers when outdoors.