Chiggers

Chiggers are the very small larvae of certain mites in the Trombiculidae family. Larvae are the immature stage between an egg and an adult mite. Chiggers are also called harvest mites or red bugs in some regions.

Chiggers live outdoors, especially in damp areas with tall grass, weeds, leaf litter, brush, or low vegetation. They can attach when a person sits, walks, works, or plays in these areas. They are most active during warm seasons, although local climate affects when exposure is likely.

Chiggers are not a disease. They also are not insects. Their temporary feeding can cause a skin reaction sometimes called trombiculiasis.

Despite a common myth, chiggers do not burrow into the skin. They attach to its surface and release saliva containing enzymes that break down nearby skin cells. The larva then feeds on that tissue. It does not drink blood.

A chigger is almost too small to see without magnification. When it reaches exposed skin or crawls under clothing, it looks for a suitable feeding place. Common sites include the ankles, waist, groin, armpits, behind the knees, and areas where socks or other clothing fit closely.

The larva pierces the outer layer of skin and releases digestive enzymes. The skin responds by forming a narrow feeding tube called a stylostome. This tube is made from hardened skin material; it is not the mite itself.

The body’s immune response to the saliva and feeding tube causes inflammation and itching. The feeding is usually not noticed when it starts. Itching and red bumps often appear several hours later, by which time the chigger may already have been washed or scratched away.

Only the larval stage feeds on people and other animals. Older mite stages live in the environment and feed on small insects or organic material. Chiggers do not mature or reproduce on the human body.

Chigger exposure can produce very itchy, red, raised bumps. Some develop a small blister. The bumps may appear in groups or lines where clothing restricted the mites’ movement.

The itching can continue after the chiggers are gone because the immune reaction remains active. Persistent itching does not mean that mites are still living under the skin.

Scratching can damage the skin and allow bacteria to enter. This is the main health concern in places where chiggers do not transmit infection.

In the United States, chiggers are not known to spread disease to people. In parts of the Asia-Pacific region, however, certain chigger species can transmit scrub typhus, an infection caused by Orientia bacteria. Travel location therefore matters when a clinician assesses fever or illness after a possible exposure.

Chigger reactions can resemble other skin problems. These include flea or bedbug bites, contact dermatitis, scabies, and bites from other mites. The pattern alone may not identify the cause with certainty.

The most likely complication is a secondary bacterial skin infection caused by scratching. Conditions such as impetigo or cellulitis may cause increasing redness, warmth, swelling, tenderness, crusting, drainage, or pus.

Scrub typhus is a separate bacterial disease linked to infected chiggers in regions where the bacteria circulate. It can cause fever, headache, body aches, swollen lymph nodes, rash, or a dark scab at the feeding site. These problems should not be assumed to be an ordinary skin reaction, particularly after travel in an affected region.

A severe allergic reaction is uncommon but requires emergency care. Call emergency services for:

• Trouble breathing, wheezing, or throat tightness
• Swelling of the tongue, lips, face, or throat
• Fainting, severe weakness, or confusion

Seek prompt medical advice for fever, rapidly spreading redness, red streaks, worsening pain, pus, or marked swelling. Also seek prompt advice if you become unwell after possible chigger exposure during travel in an area associated with scrub typhus.

A routine appointment is appropriate when the cause of the bumps is unclear, itching is difficult to control, the reaction is not improving, or new bumps continue appearing without further outdoor exposure.

If exposure may have happened recently, shower with soap and change your clothes. Wash outdoor clothing before wearing it again. This can remove larvae that have not yet attached. Avoid forcefully scrubbing already inflamed skin, which can cause further damage.

For an itchy skin reaction:

• Use a cool, damp cloth on the affected area
• Avoid scratching and keep fingernails short
• Ask a pharmacist about calamine, an over-the-counter hydrocortisone product, or an antihistamine like cetirizine or loratadine
• Follow the product label and ask before use for a child, during pregnancy, or alongside other medicines

Some antihistamines cause drowsiness and may affect driving, alcohol use, or other medicines. A pharmacist can help you choose an appropriate option.

Do not apply bleach, gasoline, kerosene, pesticides, or other household chemicals to the skin. Nail polish is also unnecessary. Chiggers are not sealed beneath the skin, and these products can irritate or burn it.

To reduce future contact, avoid sitting directly in tall grass or brush when possible. Wear long trousers, socks, and closed shoes in likely habitats. An Environmental Protection Agency-registered insect repellent may be used according to its label. Permethrin products are intended for clothing and gear when the label allows; they should not be applied directly to skin.

There is no routine blood test for an uncomplicated chigger reaction. A clinician usually considers the appearance and location of the bumps, recent activities, travel, and other possible causes. Keep a record of where you were outdoors, when the itching began, and whether fever or other illness developed.

Can I see chiggers on my skin?

Usually not. They are extremely small and may be gone before itching begins. Magnification can sometimes reveal a larva during early exposure, but finding one is not usually necessary.

Do chiggers burrow into the skin?

No. They remain on the surface and feed through a temporary tube formed in the outer skin. The inflammation left behind can make it seem as though something remains inside.

Are chiggers contagious?

No. The skin reaction does not spread from person to person. Chiggers come from the outdoor environment rather than from contact with someone who has bumps.

Why are bumps often around the waist or ankles?

Chiggers may stop where clothing presses against the skin or where their movement is blocked. Sock lines, waistbands, and skin folds are therefore common locations.

Can chiggers infest a home?

They do not usually establish a continuing indoor infestation like bedbugs or fleas. Larvae may be carried inside temporarily on clothing, so laundering recently worn outdoor clothes is reasonable. Repeated unexplained bites indoors may have another cause and deserve routine assessment.

Can pets bring chiggers indoors?

Pets can encounter mites outdoors and may develop their own skin irritation. Chiggers do not normally move from a pet and establish themselves on a person. A veterinarian can assess persistent itching or skin changes in an animal.

Why does the itching continue after washing?

Washing may remove remaining larvae, but it does not immediately stop the immune reaction already underway. Seek routine advice if the reaction keeps worsening or fails to settle.