What Is Scrub Typhus?

Medically Reviewed by Melinda Ratini, MS, DO on July 13, 2023
Written by Shishira Sreenivas
5 min read

Scrub typhus, also known as bush typhus, is a disease caused by bacteria called Orientia tsutsugamushi. You can get it if an infected chigger – larvae that grow into mites – bites you. Chiggers often pick up the bacteria when they feed on the skin cells of infected rats or mice. 

Chiggers are so tiny that they’re practically invisible to the naked eye. Chiggers are usually red, yellow, or orange in color. 

Scrub typhus is typically found in: 

  • Rural southeast Asia
  • Indonesia
  • China
  • Japan
  • India
  • Northern Australia 

It also was detected in North Carolina in July 2023. 

The disease affects people of all ages and genders equally. Globally, it’s estimated that around 1 million cases of scrub typhus occur each year.

You’re more likely to get it if you come in contact with or are exposed to areas where the chiggers tend to stay. This can include rural or forested areas that have overgrown lawns and weeds, shrubs and bushes, leaf litter, berry patches, edges of woodlands, and other areas that are damp and have shade. 

The bugs are often more active during the late spring and summer seasons. 

 

When the infected chigger bites you, it’s often painless and you might not notice it. But within a few hours, you’ll start to itch intensely and see a small, reddish welt or sore around the bite. 

The bacteria’s incubation period inside your body is about 6-10 days. Scrub typhus symptoms may start suddenly at around 10-12 days after the bite. 

This can include:

  • Fever
  • Chills
  • A black or dark scab over the bite mark known as “eschar” that usually forms after you get the fever
  • Rashes
  • Headaches
  • Body aches and muscle pain
  • Confusion
  • Swollen lymph nodes
  • Bloodshot eyes
  • Vomiting
  • Diarrhea
  • Lung infection

In severe cases, if you don’t get timely medical help, you can go into a coma or have organ failure. You could have bleeding and other complications.

Call your doctor right away if you notice any symptoms, especially if you've traveled to areas with high levels of scrub typhus-infected chiggers.

Your doctor will look at the bite mark and check for other visible signs of scrub typhus. They may also take a biopsy (a sample) of the rash and run tests to check for antibodies from the bacteria to confirm. 

Scrub typhus is often underdiagnosed as a cause of tropical fever. For an accurate diagnosis, they’ll need to rule out other conditions like malaria, typhoid fever, dengue, and leptospirosis.

Sometimes, if they aren’t able to diagnose you properly, they may have to redo the blood tests 1-3 weeks later to check for spikes in antibody levels. In such cases, your doctor may start your treatment early while you wait for results.  

 

Antibiotics are the most effective treatment for scrub typhus. The earlier you start treatment, the faster you’ll get better.

Your doctor will most likely give you doxycycline (Doxy-100, Monodox, Oracea). It’s a drug you take by mouth two times a day for 7 days or more. You can also get the drug through an IV in your vein. 

For most children, the CDC recommends a shorter course of 5 days if they have a mild illness. This helps to avoid drug side effects like teeth staining or weak tooth enamel. 

If you're pregnant or allergic to this antibiotic, there are other options. Azithromycin (Zithromax, Zithromax Z-Pak, Zmax) is effective.

Chloramphenicol may be another option.  

If the disease and symptoms are left untreated, it can trigger severe organ complications. These include:

Heart problems. The condition can disrupt your heart rhythm and cause issues like atrial flutter, fibrillation, sinus tachycardia, and bradycardia. This can be seen with an electrocardiogram (EKG). 

You can also develop myocarditis. That's when your heart wall becomes inflamed. It’s rare and can cause fever, breathing difficulty, heart palpitations, or sudden cardiac death.

Gut issues. It’s possible to develop stomach problems 3 to 7 days after your fever starts. This can include vomiting, nausea, diarrhea, liver issues, bleeding in your gut, and pancreatitis. Your stomach might feel tender, have pain, and have indigestion. Doctors don’t know what exactly causes this.

Breathing problems. In severe cases of scrub typhus, you could develop acute respiratory distress syndrome (ARDS), a life-threatening condition in which you have lung injury and fluid leaks in your lungs. This makes it very hard for you to breathe and get the proper amount of oxygen into your body.

Kidney injury. Scrub typhus can cause an underdiagnosed complication called acute kidney injury (AKI). This can cause your kidneys to fail and lead to septic shock. You’re more likely to get it if you have other co-existing health problems when you develop scrub typhus. 

Neurological issues. The bacterial infection can cause problems with your central nervous system, such as scrub typhus meningitis (inflammation around the brain that can also cause severe headaches). You could also get a more severe condition called meningoencephalitis, which can cause seizures and changes in your thinking and behavior. You may also develop visual hallucinations and nerve pain. But getting treated early can ease symptoms and help you get better faster.

Call your doctor or head to the emergency room ASAP if you have any of these symptoms.

There’s no vaccine to prevent scrub typhus.

The best way to lower your odds of scrub typhus is to take precautions to prevent getting a chigger bite or contact in any form.

If you’re hiking or exposed to areas with a high chigger population, you should:

  • Cover your arms and legs. Reduce exposed skin.
  • Use insect repellent like DEET on exposed skin and clothes.
  • Don’t sit on the grass directly.
  • Apply sunscreen after you put on the repellent.

For babies and children, cover their arms and legs. If you’re using a stroller or carrier, make sure to cover it with a protective net. 

Don’t spray insect repellent directly onto your child’s skin, especially if they have any cuts or wounds. Spray it onto your hands and spread it on their skin. For children under 2 years of age, check with their doctor first before applying insect repellent.

If you’ve been exposed, wash all of your clothes and gear in hot water for about 30 minutes. Take a hot shower and use soap to scrub exposed areas well. 

You can also pre-treat your clothing, boots, and other outdoor gear with 0.5% permethrin or purchase permethrin-treated items before you head outdoors to add a layer of protection. This can kill chiggers and the treatment can protect multiple washes. 

Closely read the product information and instructions. Don’t use it on your skin. It’s meant for clothing and gear only.