chiggers

Chiggers are the larval stage of certain mites in the family Trombiculidae. They are tiny (often less than 1 mm to a few millimeters), and although most species feed on small animals, some attach to humans who pass through grassy or brushy habitats. Adults and nonfeeding life stages live in the environment and do not require a host.

During feeding, a chigger larva attaches to the skin and injects saliva containing enzymes that break down skin cells. This creates a feeding site rather than a bite in the traditional sense. The larva then feeds on the dissolved tissue for a few days and eventually detaches. The irritation and itch that follow are caused by the host’s reaction to the enzymes and other components in the larva’s saliva, not by the mite itself remaining embedded.

Symptoms typically appear hours to days after exposure and include intense itching and clusters of small red bumps or blisters at exposed sites such as the waist, ankles, groin, and armpits. The lesions are not contagious. Diagnosis is usually based on history of outdoor exposure and the characteristic itching and skin reaction; there is no specific test for chigger bites in most cases.

Treatment focuses on relieving itching and preventing secondary infection. Options include cool compresses, oatmeal or calamine baths, and short courses of topical corticosteroids or oral antihistamines. Cleaning the skin and avoiding scratching help prevent infection. Infections should be treated by a healthcare provider. Most bites resolve within several days to a week.

Prevention includes avoiding contact with tall grass and brush, using insect repellents containing DEET, treating clothing with permethrin, and showering after outdoor activities. Chiggers are found worldwide, with disease risk varying by region; in some areas, certain species can transmit scrub typhus, a serious illness, highlighting regional differences in risk.