Canine Health Menu

Trombiculid Mites

Issue Description
Chiggers attach to the host, inject digestive enzymes into the bite wound, and then suck up the digested tissue. They do not burrow into the skin or suck blood, as is commonly assumed. Itching from a chigger bite may not develop until 24-48 hours after the bite, so the victim may not associate the specific exposure with the bite itself. The red welt/bump on the skin is not where a chigger laid eggs, as is sometimes believed. Warm, rainy days make these parasitic and predatory mites reproduce into large populations. Once the ground temperature is regularly above 60 °F (16 °C), the harvest mite lays eggs. Therefore, from April through early autumn up until the first frost, humans are susceptible to chigger bites. It is the larval stage that feeds on humans (as accidental host) or more commonly on other animals (small mammals, birds, reptiles, and amphibians).

Chiggers do not like sunlight or humidity. During the wet season, chiggers are usually found in tall grass and other vegetation. During dry seasons, chiggers are mostly found underneath brush and shady areas.

When carrying the parasite Orientia tsutsugamushi, chigger bites can cause scrub typhus.

Other Names
Chiggers, Harvest Mites, Red Bugs, Berry Bugs, Scrub-itch Mites


Symptoms
The main symptoms are severe itching and red pimple-like bumps (papules) or hives. The skin rash may appear on sun-exposed area only. The rash may also stop where the underwear meets the legs. This is is often a clue that the rash is due to chigger bites.

Treatment and Prevention
Keep grass short, and remove brush and wood debris where potential mite hosts may live. Keep major hosts away from the area, such as rodents and other small mammals. Secure trash cans to discourage wildlife from coming near your home. Sunlight that penetrates the grass will make the lawn drier and make it less favorable for chigger survival.

For personal protection, apply insect repellent to feet, legs, and mid-section.
To reduce the itching, an application of anti-itch cream containing hydrocortisone, calamine, or benzyl benzoate is often used. Applying fingernail polish to the affected area does not kill the chigger; the chigger is actually no longer present by the time a rash is noticed.


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