The Case of the Mysterious Rash

A 58 year old Chinese Missionary without any chronic co-morbidity or drug allergies, presented to our ED with an intensely itchy rash to his feet and body after recent travel to Tanzania a week ago.
His vital signs were stable and there was no fever or constitutional upset.
Morphology of the rash on his foot, as per photograph shown below -




Q1. What is the diagnosis?
Q2. What is the causative agent?
Q3. What is the commonest presentation?
Q4. What is the management ?
Q5. How can it be prevented?


A1. Chiggers or Jiggers


A2. Trombiculid mite larvae (also Known as Chiggers); Chiggers attach to the host and pierce the skin injecting enzymes into the bite that aims to digest cellular contents.
A3. Three or more hrs after the bite, itching usually starts (and peaks at 1-2 days post bite) and area of the bite may be reddened and resembles a blister or a pustule.
A4. Topical anaesthetic to provide short term relief, Chiggerex ointment provides relief from both pain & itch
       Soaking bitten area in water + Epsom salts can cause the chiggers to become detached
       Topical isopropyl alcohol can also remove the chiggers
       Antihistamines orally + antipruritic lotion, such as Calamine lotion
       Topical steroids to suppress inflammatory reaction
       Treat any supervening bacterial cellulitis with antibiotics (augmentin)
       Consider Dermatology review
A5. All mosquitoe repellents, applied to skin and clothing, are effective at repelling chiggers