Scrub Typhus (Bush Typhus)

Symptoms of scrub typhus begin with a sore on the skin with a punched-out appearance where the chigger is attached.

Scrub typhus, also known as bush typhus, is a rickettsial disease caused by the bacterium Orientia tsutsugamushi (formerly Rickettsia tsutsugamushi). It is transmitted by the bite of a mite called chigger that is infected with the bacterium.

Scrub typhus is common in people living in the rural areas of Southeast Asia, Indonesia, China, Japan, India, and northern Australia. People exposed to areas with scrub vegetation where rodents live, such as forest clearings, riverbanks, grassy areas, deserts, and rain forests, are at a high risk of this disease.

The symptoms start 6 to 21 days after exposure to the bacterium. Symptoms start with a sore on the skin with a punched-out appearance at the site where the mite is attached.

Other symptoms appear several days after the appearance of the ulcer and may include:

• Fever that increases during the first week (often from 104°F to 104.9°F)
• Chills
• Severe headache
• Severe bloodshot eyes 
• Sweating
• Swollen lymph nodes
• Rash
• Lung infection
• Vomiting 
• Diarrhea
• Cough during the first week
• Pneumonitis (may develop during the second week)

In severe cases, symptoms of scrub typhus may include:

• Increased pulse rate
• Declining blood pressure
• Confusion
• Coma
• Deafness
• Difficulty swallowing
• Enlarged spleen

Usually, the physician diagnoses scrub typhus based on the symptoms. The presence of a sore and fever can confirm scrub typhus. It is also critical to inform your doctor about any previous travel to chigger-endemic areas. It will help physicians diagnose the infection quickly and initiate treatment without losing time. Another way to diagnose scrub typhus is to send blood samples for various laboratory tests.

Other tests that may be ordered by the physicians to diagnose scrub typhus include:

• Biopsy of rash: It involves staining of rash with fluorescent antibodies to detect the organisms.
• Serologic testing: Weil-Felix test is the cheapest and most used serologic test for detecting antibodies.
• Polymerase chain reaction: They are highly sensitive and accurate. 

Symptoms of scrub typhus may be similar to those of Rocky Mountain spotted fever and epidemic typhus. However, scrub typhus is prevalent in different geographic areas compared with these epidemics.

Antibiotics are the first-line treatment of scrub typhus. They are more effective when given after the treatment has begun.

The primary antibiotics given to manage scrub typhus include:

• Doxycycline is administered in doses of 200 mg orally once followed by 100 mg two times a day in adults until the person remains feverless for 48 hours and has undergone treatment for seven days.
• In children, a course of doxycycline 2.2 mg/kg orally or two times a day intravenously is given for five days in case of mild illness and 10 days for high-risk disease.
• Pregnant women are given trimethoprim/sulfamethoxazole 160 mg/800 mg two times daily for up to 32 weeks of pregnancy.
• Pregnant women who are severely allergic to doxycycline are given azithromycin (500 mg on the first day followed by 250 mg daily for two to four days).
• Chloramphenicol is given as an alternative. The usual dose for chloramphenicol is 500 mg orally or intravenously four times a day for seven days.

As there is no vaccine available for treating scrub typhus, it is better to follow prevention measures to avoid getting infected.

Some of the ways you can prevent a scrub typhus infection include:

• Avoid traveling to areas with lots of vegetation where chiggers are commonly found.
• Use insect repellents approved by the Environmental Protection Agency and follow the instructions mentioned on the product label.
• Never use any repellents on children younger than two months.
• Always wear protective clothing and a hat that gives maximum protection against chigger bites.
• Never apply repellents directly on a child’s face. Adults should first spray insect repellents onto their hands and then apply them to their child’s faces.
• Treat your clothes with permethrin or purchase permethrin-treated items.