Scrub Typhus: Symptoms, Eschar, Test Choice and Treatment

Scrub typhus is a bacterial infection caused by Orientia tsutsugamushi, spread by the bite of infected mite larvae called chiggers. It causes fever, headache, body ache and often a dark scab called an eschar at the bite site. It is common in parts of India, especially after the monsoon, and it is easy to treat when caught early: doctors start the antibiotic doxycycline as soon as they suspect it, without waiting for lab confirmation. Delay is what makes it dangerous.

Because it looks like dengue, malaria, typhoid and other fevers, scrub typhus is often missed in the first week. This guide explains how it spreads, the symptoms, how to spot an eschar, which test to ask for and when, how it is treated, what complications to watch for and how to avoid it.

How scrub typhus spreads

The bacteria live in chigger mites, which are carried by field rodents and found in scrub vegetation, grass, bushes and farmland. A chigger bites to feed on tissue fluid and, if infected, passes the bacteria into the skin. It does not spread from person to person by touch or coughing.

Common risk situations:

• Farming, harvesting and working in fields
• Walking or trekking through tall grass or forest edges
• Camping and picnics in bushy areas
• Living near overgrown land or gardens with rodents
• Children playing in grass

In India, cases are reported from many states, including the Himalayan belt (Himachal Pradesh, Uttarakhand), Haryana, Rajasthan, Tamil Nadu, Kerala, West Bengal, Assam and others. They rise in the rainy and post-monsoon months, from roughly July to November.

Symptoms

Symptoms start after an incubation period of about 6 to 21 days (commonly around 10 days).

Early features

• Sudden high fever with chills, often lasting more than a week if untreated
• Severe headache
• Body and muscle pain
• Weakness and tiredness
• Cough, nausea or vomiting
• Swollen lymph glands near the bite
• A rash, usually appearing in the second week, mostly on the trunk

The eschar

An eschar is a painless black or dark scab with a red rim, often 0.5 to 2 cm, at the site of the bite. It usually appears on a skin fold, such as the armpit, groin, waist line, behind the knee, under the breast or around the genitals, and can be easy to miss. It doesn't itch, so many people do not notice it. In reported series from India, an eschar is found in a large share of patients when doctors look carefully, though the proportion varies widely. Not having an eschar does not rule out the disease.

Always ask your doctor to examine skin folds, scalp, back and genital area. If you find a dark painless scab with a fever, say so.

Complications of untreated or late disease

• Pneumonia or lung involvement with breathlessness
• ARDS (severe lung injury)
• Meningitis or encephalitis (confusion, seizures)
• Hepatitis (raised liver enzymes, jaundice)
• Kidney injury
• Low platelet count and bleeding
• Myocarditis
• Shock and multi-organ failure

With prompt treatment, most people recover fully. Without it, complications can be serious and sometimes fatal.

Scrub typhus or dengue, typhoid, malaria?

All cause fever and body ache. Pointers that make a doctor think of scrub typhus:

• Fever lasting beyond 5 to 7 days with no clear source
• An eschar or a history of exposure to fields or bushes
• Enlarged lymph nodes
• Rash after several days
• Low platelets, raised liver enzymes and breathlessness together
• No response to standard fever treatment

Doctors often test for dengue and malaria first, because those are common, and then for scrub typhus if the fever persists. In some regions, all are checked together.

Which test to ask for

| Test | Use | Comments | |---|---|---| | Scrub typhus IgM ELISA | Most widely used test | Antibodies usually appear after about day 5 to 7 of illness, so a test in the first few days can be negative. Repeat if suspicion stays high | | PCR (from blood or eschar tissue) | Early confirmation | Can detect infection in the first week, before antibodies; availability is limited | | Immunofluorescence assay (IFA) | Reference method | Mostly in reference labs | | Rapid card tests | Quick screening | Convenience, but accuracy varies | | Weil-Felix test | Older test | Poor sensitivity and specificity; not recommended on its own | | Routine blood tests | Supportive | Low platelets, raised liver enzymes, low or normal white cell count and raised CRP are common |

Most important point: treatment should not wait for the test. A negative early IgM does not rule out scrub typhus, and doctors who suspect it based on symptoms, season and exposure usually start doxycycline right away and arrange follow-up testing.

Treatment

• Doxycycline is the first-choice antibiotic for adults and, for short courses, for children as well. The doctor decides dose and duration; typically a course of about 7 days. Fever often settles within 24 to 48 hours of starting the right drug, and that response itself supports the diagnosis.
• Azithromycin is an alternative, often used in pregnancy and for young children where doxycycline is avoided.
• Supportive care: fluids, fever control with paracetamol, oxygen when needed, and intensive care for severe disease.
• Severe cases: hospital admission, sometimes with combination antibiotics and organ support.

Don't self-medicate with antibiotics, and don't stop the course early. Avoid anti-inflammatory painkillers when platelets may be low.

Recovery

Most patients feel much better within a few days and recover over one to two weeks. Tiredness can linger. There is no vaccine, and a previous infection doesn't give lasting protection against other strains.

When to go to hospital

• Fever for more than 5 days with no explanation
• Breathlessness or fast breathing
• Confusion, severe headache, stiff neck or seizures
• Persistent vomiting or inability to drink
• Reduced urine output
• Bleeding, black stools or severe weakness
• Jaundice
• Pregnant women, young children, older adults or people with diabetes who have fever and rash

Scrub typhus in pregnancy and children

Pregnancy needs urgent attention, because the infection can cause complications for mother and baby. Doctors choose a safe antibiotic. Children can have a milder or severe course; in young children, ask for medical review early.

A typical course, day by day

Knowing the usual timeline helps you recognise when a fever is not behaving like a simple viral illness.

| Days after the bite | What often happens | |---|---| | 1 to 10 | No symptoms. A small, painless bump or scab may form at the bite and go unnoticed | | 10 to 12 | Sudden fever with chills, headache, body ache | | 3 to 5 days of fever | Eschar visible in some people, swollen glands near it, red eyes, tiredness | | Around day 5 to 8 of fever | Rash on the trunk may appear; cough or breathlessness may begin; platelets and liver tests start to change | | After day 8 to 10 without treatment | Risk of lung, brain, kidney and liver complications rises sharply | | 24 to 48 hours after starting the right antibiotic | Fever usually begins to settle |

If you have had fever for five days or more after being outdoors in the monsoon season, and your doctor has only treated you with fever tablets so far, it is reasonable to ask: "Could this be scrub typhus?"

What to tell your doctor

• Where you were in the last three weeks: farm, forest edge, trek, camping trip, village visit, overgrown garden
• When the fever began and whether it has been continuous
• Any dark scab, bite mark or sore, including in the groin, armpits, waistline, behind the ears or under the breasts
• Any rash, cough, breathlessness, confusion or vomiting
• Whether you are pregnant, diabetic or on long-term medicines
• Medicines you have already taken, especially antibiotics

This short history is often what leads a doctor to the diagnosis.

Prevention

There is no vaccine, so prevention is about avoiding bites.

• Wear long sleeves, long trousers and closed shoes in grassy or bushy areas, and tuck trousers into socks.
• Use an insect repellent containing DEET or picaridin on skin and clothing, as directed.
• Don't sit or lie directly on grass or bare ground; use a mat.
• After outdoor exposure, shower and change clothes, and check skin folds.
• Keep your yard and field edges clear of tall grass and bushes.
• Control rodents around homes and storage areas.
• Wash clothes and bedding after trekking or camping.
• Farm workers: wear protective clothing and wash after work.

Frequently asked questions

What are the symptoms of scrub typhus?

Fever with chills, severe headache, body pain, weakness, sometimes a rash, swollen glands and a painless black scab (eschar) at the bite.

How is scrub typhus diagnosed?

By clinical suspicion and tests such as IgM ELISA, PCR or IFA. Doctors usually begin treatment before the results.

Which antibiotic treats scrub typhus?

Doxycycline is the first choice; azithromycin is an alternative, for example in pregnancy.

Can scrub typhus spread from person to person?

No. It is spread only by infected chigger bites.

Is scrub typhus dangerous?

It can be if treatment is delayed, because of complications such as pneumonia, brain and kidney involvement. Early treatment gives excellent recovery.

Why is my scrub typhus test negative?

Antibodies appear late. A test in the first week can be negative. Repeat, or use PCR, and tell the doctor if fever continues.

How long does scrub typhus fever last?

Without treatment, up to two weeks or longer. With the right antibiotic, fever usually settles within two days.

When to see a doctor

See a doctor promptly for any fever lasting more than three to five days, especially after outdoor exposure, or with a rash, a dark scab, breathlessness or confusion. Do not wait for it to pass.

Care at Prakash Hospital Noida

Whether you live in Sector 18, Sector 62, Greater Noida West, or anywhere nearby, Prakash Hospital Noida is a trusted name for fever and infectious disease care in Noida. Our doctors look for the less obvious causes of prolonged fever, start treatment early and monitor for complications.

To book a consultation, call the number.

Sources: Indian Council of Medical Research and published clinical reviews on scrub typhus in India; WHO and CDC guidance on rickettsial diseases. Test sensitivity varies by timing and method.

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