Threat of Scrub Typhus: Symptoms, Transmission, and Prevention

With the recent uproar about ticks, there has been a surge in patients suffering from scrub typhus due to mite infestations. Scrub typhus, which is transmitted through mites, can be treated with antibiotics, so it’s crucial to seek medical help as soon as symptoms are suspected. Since there is no vaccine available, the best preventative measure is to avoid being bitten by mites. We have looked into what symptoms appear when infected with scrub typhus and whether there are any other treatment methods apart from antibiotics.

Recent Increase in Scrub Typhus Patients by More Than Five Times

Scrub typhus caused by mites usually starts to spread around December. While it’s rare for the disease to be transmitted from person to person, it can be contracted through contact with the blood or bodily fluids of an infected patient. Also, pets can get infected from grass or lawns during walks.

Classified as a Grade 3 Infectious Disease

Scrub typhus is classified as a ‘Grade 3 Infectious Disease’ and is a febrile disease that occurs mainly in Asian regions such as Korea, Japan, China, and Indonesia. It happens when you are bitten by a mite carrying the scrub typhus bacteria. The disease primarily occurs between late autumn and early winter when the larvae are most active, with more than half of the patients contracting the disease during this period.

What Are the Symptoms of Scrub Typhus?

The incubation period for scrub typhus infection is about 10 days, and it can last up to three weeks. Symptoms similar to the common cold, such as fever, chills, headache, muscle pain, and rash, may occur, making it easy to overlook. However, a characteristic feature is the appearance of a spotted rash on the body or limbs about 3-7 days after the onset of the disease, which disappears after 1-2 weeks.

Large Scars Form

Scrub typhus leaves a large scar known as an ‘eschar,’ which is a significant finding for diagnosis. The bite mark initially forms a papule, which then turns into a vesicle and ulcer, and is finally covered with a black eschar. The eschar is typically surrounded by a red rash, and typical eschar forms around the time symptoms appear. It mainly spreads on the front of the body, with men often showing it within about 12 inches around the navel, and women often showing it above the navel and below the chest.

Larvae Are More Dangerous Than Adults

Mites live parasitically during their larval stage and live freely as nymphs or adults. After hatching, the larvae stay on the ground until they meet a host, then they attach to the skin. In humans, they usually attack near the socks or waist. They create a blood-sucking tube on the skin, fill it with saliva, and continue sucking blood for several days. After the blood-sucking is over, they leave the tube in and fall to the ground, where they go through the nymph stage and become adults.

Do All Mites Cause Scrub Typhus?

Not all mites cause scrub typhus. Of the 51 species of mites identified in Korea, seven are known to be vectors of the scrub typhus bacteria. In addition, only the larvae of mites infected with the scrub typhus bacteria can cause another infection, with the ‘Leptotrombidium pallidum’ being the most common species.

Diagnosis of Scrub Typhus

Typically, a blood test shows a decrease in white blood cells and platelets, accompanied by hypoalbuminemia, hematuria, and proteinuria. A positive result in the antibody test through serum reaction and a four-fold or more increase in antibody values over time confirm the diagnosis. Also, through chest X-ray imaging, you can see inflammation spreading from the center of the lung to the peripheral tissue. The X-ray image shows a blurry and unclear boundary, indicating lung infiltration.

Will There Be No Re-Infection Once Infected?

Patients who recover from scrub typhus gain immunity to the same serum type for a certain period, but only temporary immunity to other serum types of the bacteria. Therefore, there is always a possibility of re-infection, and in fact, those living in an area where scrub typhus is prevalent may experience multiple re-infections.

Early Treatment is Important

Scrub typhus is not a disease that is transmitted from person to person, but early treatment is very important. Especially for people with underlying diseases such as liver, kidney, or lung diseases, it’s necessary to be cautious due to complications. Tracking studies on people infected with scrub typhus have shown that the risk of cardiovascular disease increases, so the best measure is to prevent being bitten by mite larvae.

Avoid Outdoor Activities and Picnics

It’s best to avoid outdoor activities as much as possible, and if you must, wear clothing that minimizes exposure to mites. Long-sleeved clothes, hats, scarves, socks, and gloves in light colors are essential and do not leave clothes on the grass or sit on the grass without a mat. It’s good to frequently spray insect repellent and wash clothes immediately upon returning home.

By. Shin Young Jeon