trombiculosis; trombiculiasis; trombiculidiasis; chiggers

Etiology

• infestation with larvae of trombiculid mites (chiggers)

Epidemiology

• commonly found on the tip of blades of grasses

Pathology

• chiggers feed on skin cells
• mite saliva causes pruritus & dermatitis
• risk of secondary infections with scratching

Clinical manifestations

• chiggers seem to affect warm covered areas of the body
• bites often clustered behind the knees, or beneath tight undergarments
• intense pruritus
• hard raised bumps common

* image (abdominal chiggers 36 hours after exposure)

Complications

• conjunctivitis
• may transmit Orienta tsutsugamushi in East Asia & Austronesia (Taiwan, Madagascar, Philippines, Torres Strait Islands Australia) etiologic agent of scrub typhus

Management

• local application of alcohol compresses or zinc lotions
• external application of agents containing polidocanol or glucocorticoid
• systemic antihistamines indicated to control itching

More general terms

• mite-borne infection
• infestation; ectoparasitic infection