Key points
- Scrub typhus is spread by chigger mite larvae. In Korea, most cases occur in October and November each year. It is also common across much of Asia and the western Pacific.
- If you develop a high fever, chills, headache and aches within 1–3 weeks of time in grassy areas, don't write it off as a cold; tell the doctor about your outdoor activity.
- A black scab (eschar) where you were bitten is an important clue. With early antibiotic treatment, most people recover well.
What is scrub typhus?
Scrub typhus is caused by the bacterium Orientia tsutsugamushi, passed on when an infected chigger (mite larva) attaches to the skin and feeds. Chiggers are only about 0.2–0.4 mm long, so bites usually go unnoticed. It does not spread from person to person.
According to the Korea Disease Control and Prevention Agency (KDCA), thousands of cases are reported in Korea every year, mainly in October and November: 6,268 in 2024 and 3,405 in 2025. In 2026, KDCA is again monitoring chiggers at 18 sites nationwide from August 26 to December 16.
By the end of September 2026, 148 cases had been reported nationwide; that is before the main autumn season, so it is too early to judge this year's size. On November 3, Cheongyang County in South Chungcheong reported 21 cases so far this year, more than double the same period last year (9). Cases are most common among people over 50, who are often involved in grass cutting at family graves, chestnut and acorn gathering, harvest work and hiking.
Main symptoms
The incubation period is usually 1–3 weeks. Because of this gap between the outing and the first symptoms, scrub typhus is easily mistaken for a cold or flu.
- Sudden high fever and chills, severe headache
- Muscle aches all over, weakness
- A black scab (eschar): the bite site swells red, then the center turns into a black crust, usually 5–20 mm across. It is often painless and not itchy, so it is easy to miss.
- A red rash that may appear a few days after the fever, starting on the trunk and spreading to the limbs
- Swollen lymph nodes, for example in the armpit or groin near the scab
Where to look for the eschar
Chiggers crawl under clothing and tend to bite where skin folds or clothing is tight. If you have a fever with no clear cause, ask a family member to help check these areas.
| Common site | How to check |
|---|---|
| Armpits and groin | The most common sites. Use a mirror or ask someone to help. |
| Under the waistband or elastic of underwear | Check all the way around the abdomen and waist. |
| Back of the knees and buttocks | Be sure to check if you sat on grass or squatted while working. |
| Neck, behind the ears, scalp | Easy to miss under hair. |
| Under the breasts | Check beneath the bra line. |
Not finding a scab doesn't rule out scrub typhus. It may be small or hidden, so a fever after outdoor activity is reason enough to see a doctor.
Scrub typhus self-check
If these apply, scrub typhus is possible and it is best to see a doctor. This does not replace a diagnosis.
- In the past 3 weeks you spent time in grass or brush: grass cutting at graves, field or harvest work, hiking or camping, or gathering chestnuts.
- You suddenly have a fever of 38°C (100.4°F) or higher, with chills, headache and aches.
- You have a painless black scab or a red rash somewhere on your body.
- Your fever hasn't come down for several days despite cold medicine or fever reducers.
Telling autumn fevers apart
Several fever illnesses linked to outdoor activity rise in Korea in autumn. Symptoms overlap and blood tests are used to tell them apart, so telling the doctor when, where and what kind of outdoor activity you did helps a great deal.
| Illness | Spread by | Features |
|---|---|---|
| Scrub typhus | Chigger larvae | Peaks in October–November; eschar and rash; treated with antibiotics |
| Severe fever with thrombocytopenia syndrome (SFTS) | Hard ticks | April–November; high fever with vomiting and diarrhea, low platelets; high fatality rate, no vaccine or specific treatment |
| Hemorrhagic fever with renal syndrome | Field-mouse droppings (inhaled in dust) | Late autumn to early winter; high fever, then bleeding tendency and reduced kidney function; a vaccine exists for high-risk groups in Korea |
| Leptospirosis | Water or soil contaminated with rodent urine | After rice-paddy work at harvest; high fever, severe calf pain, red eyes |
How is it treated?
Scrub typhus is treated with antibiotics such as doxycycline. With early treatment, the fever usually breaks within a day or two. There is no vaccine. Delayed treatment can lead to complications such as pneumonia, meningitis and reduced kidney function, so early care is especially important for older adults.
Because there are several strains, you can get it again even if you have had it before. Taking leftover antibiotics at home can delay the diagnosis, so take only what is prescribed.
See a doctor promptly if
- You develop a fever 1–3 weeks after outdoor activity and notice a black scab or rash
- Your fever lasts more than three days despite fever reducers
- You become short of breath or confused, or are urinating much less
- You have a high fever with severe vomiting or diarrhea (possible SFTS)
Prevention
Before going out
- Wear long sleeves, long pants, gloves and boots, and tuck your pant legs into socks or boots.
- Apply a tick and mite repellent to exposed skin and clothing. It lasts only a few hours, so reapply during long work.
While outdoors
- Don't sit or lie directly on grass; use a mat, then shake it out and dry it in the sun.
- Don't relieve yourself in the brush or leave clothes on the grass.
- Stay on marked trails.
After coming home
- Shower right away and check your armpits, groin, waist, the backs of your knees and behind your ears.
- Shake out the clothes you wore and wash them right away, separately from other laundry.
- Watch for fever for 3 weeks, and if one develops, tell the doctor about your outdoor activity.
Myths: true or false?
| Myth | What the evidence says |
|---|---|
| No black scab means it isn't scrub typhus | The scab may be small or hidden. A fever after outdoor activity warrants a visit even without one. |
| I didn't feel a bite, so I'm fine | Chiggers are tiny and bites are often painless and not itchy, so most people never notice. |
| Once you've had it, you're immune for life | There are several strains (serotypes), so reinfection is possible. |
| Once it gets cold, there's nothing to worry about | Chiggers stay active into late autumn until frost, and with an incubation of up to 3 weeks, cases keep appearing through late November. |
Please keep in mind
- This article is based on information checked as of the date shown above. New research or changes in official guidance may change the content, so please use it as a reference rather than as definitive advice.
- For an accurate diagnosis and advice about your own health, please see a doctor in person.