What are the signs and symptoms of chigger bites?

Signs and Symptoms of Chigger Bites

Chigger bites present as intensely pruritic erythematous papules and papulovesicles that develop at feeding sites, typically self-resolving within 1-2 weeks with symptomatic treatment only. 1

Primary Cutaneous Manifestations

The characteristic presentation includes:

• Pruritic erythematous papules that develop where chigger larvae attach and feed on epidermal cells 1, 2
• Papulovesicular lesions at bite sites, representing the host immune response combined with digestive enzymes secreted by the mite 2
• Intense pruritus as the hallmark symptom, which is the usual response to infestation 2

Distribution and Location Patterns

Chigger bites typically occur in areas where:

• Clothing fits tightly or where skin folds exist, as larvae seek warm, moist areas
• Exposure occurred in high grass, weeds, and low brush during outdoor activities 3
• The bites are often clustered in groups rather than isolated lesions

Progressive Immune Response with Repeated Exposure

The clinical presentation varies significantly based on prior exposure history:

• First exposure: Minimal to no macroscopic changes at attachment sites initially 4
• Second exposure: Approximately 20% develop visible reactions, though less intense than subsequent exposures 4
• Third and fourth exposures: Marked reactions consisting of erythema, epidermal thickening, and serous exudation develop 4
• Cellular infiltration: With repeated exposures, attachment sites show infiltrates of lymphocytes, eosinophils (most intense), basophils, and neutrophils 4

Important Clinical Distinctions

A critical pitfall is misidentifying chigger bites as tick bites or other arthropod bites. Patients often describe pruritic, erythematous, or ulcerated cutaneous lesions as "mosquito bites, spider bites, chigger bites, or bug bites," which can be indistinguishable from actual tick bites 3. This distinction matters because:

• Chigger bites are self-limited and require only symptomatic treatment 1
• Tick bites may require consideration of tickborne rickettsial diseases requiring antibiotic therapy 3
• The absence of systemic symptoms helps differentiate simple chigger dermatitis from tickborne illness

Severe Reactions

While most cases are self-limited, more severe reactions can occur:

• Marked cutaneous reactivity develops with repeated exposures, involving both immediate and delayed hypersensitivity responses 4
• Severe pruritus may warrant intralesional triamcinolone acetonide injection in extreme cases 1
• Secondary infection can develop from excoriation, requiring documentation of progressive redness, increasing pain, purulent discharge, fever, warmth, and tenderness 5

Potential for Disease Transmission

Although rare in the United States, clinicians should be aware:

• Certain chigger species (genus Leptotrombidium and Herpetacarus) can vector Orientia species causing scrub typhus 6
• Other pathogens including Hantavirus, Bartonella, Borrelia, and Rickettsia have been detected in chiggers, though their role in US disease transmission requires further investigation 6
• Scrub typhus presents with fever, malaise, headache, and myalgia—distinct from simple chigger dermatitis 3

Timeline and Resolution

• Feeding duration: Larvae typically engorge for 9-10 days on first exposure, decreasing to 4-5 days with subsequent exposures 4
• Symptom duration: Pruritic lesions are self-healing within 1-2 weeks in most cases 1
• Peak season: Outdoor activities during April-September in areas with high grass and brush pose highest risk 3