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The death of a 20-year-old Anna University student in Chennai after being diagnosed with scrub typhus has drawn attention to the bacterial infection, which is often mistaken for other monsoon fevers such as dengue and malaria.
Harish, a final-year mechanical engineering student who lived at the university's Marutham Boys' Hostel, developed a fever and was initially treated at Kalaignar Centenary Super Speciality Hospital in Guindy. He was later referred to Kilpauk Medical College Hospital, where he died on Friday. Greater Chennai Corporation (GCC) officials said he had tested negative for dengue and had been diagnosed with scrub typhus, encephalopathy, acute respiratory distress syndrome (ARDS) and multi-organ failure.
The civic body said the death was the first reported scrub typhus death in Chennai this year, while 173 cases had been reported so far. Officials also clarified that scrub typhus is not a mosquito-borne disease and said there was no outbreak. Despite this, the corporation intensified vector control and fever surveillance measures across the city, including at educational institutions.
So what is scrub typhus and how does it spread?
What is scrub typhus?
Scrub typhus is a bacterial infection caused by Orientia tsutsugamushi, a bacterium found across several parts of Asia, including India. Unlike dengue, malaria and chikungunya, it is not spread by mosquitoes. Instead, humans contract the infection through the bite of infected larval mites, commonly called chiggers.
These mites are usually found in areas with thick vegetation, including overgrown grass, bushes, scrublands and agricultural fields. Rodents act as natural hosts for the mites, helping maintain the infection in the environment.
Most cases occur in rural areas where vegetation provides suitable habitats for the mites. However, even small patches of scrub vegetation can harbour them, meaning exposure does not necessarily require a person to spend time in a large forest or rural area.
Health agencies note that scrub typhus is endemic in several countries in South and Southeast Asia, including India, Sri Lanka, Bangladesh, Thailand, China and Japan. The infection can occur throughout the year in tropical regions, though cases often rise during and after the monsoon season.
What are the symptoms?
Symptoms usually appear within a week to three weeks after an infected mite bite. Fever is the most common symptom and is often accompanied by chills, headache, body pain and weakness. Some patients may also develop enlarged lymph nodes, nausea or abdominal discomfort.
Doctors also look for an eschar, a dark, scab-like mark at the site of the bite that resembles a cigarette burn. It is usually painless and can occur in areas such as the armpits, groin, waistline or neck. However, not all patients develop this mark.
Some patients develop a rash, which often starts on the abdomen and spreads to the limbs. The infection can become severe if not treated early, leading to complications such as pneumonia, encephalitis, kidney injury, respiratory distress and multi-organ failure.
Why is scrub typhus difficult to diagnose?
Doctors say scrub typhus is often underdiagnosed because its symptoms overlap with several other infections that cause fever, especially during the monsoon. Patients may initially be suspected to have contracted dengue, malaria or viral fever.
Diagnosis is usually based on symptoms, exposure history and laboratory tests. Blood tests and molecular tests such as PCR can help confirm the infection. However, medical guidelines emphasise that treatment should not be delayed while waiting for test results if doctors strongly suspect scrub typhus.
Scrub typhus is treated with antibiotics. Treatment decisions should be made by a doctor, particularly in pregnancy, severe disease or when there are complications.
Early treatment is important because untreated infection can progress to severe complications, including organ failure.
Can scrub typhus be prevented?
There is currently no vaccine available to prevent scrub typhus, so prevention focuses on reducing exposure to infected chiggers.
People spending time in areas with dense vegetation can reduce their exposure by wearing full-sleeved clothing, long trousers and closed footwear. Insect repellents containing DEET or other suitable active ingredients can also be used on exposed skin and clothing.
Keeping lawns and vegetation around homes trimmed can reduce potential mite habitats. Maintaining clean surroundings and controlling rodents can also help reduce exposure. After spending time in bushy or forested areas, people are advised to bathe and wash their clothes.
Because fever and other early symptoms can resemble several common infections, people who develop symptoms after spending time in areas where scrub typhus occurs should tell their healthcare provider about that exposure. Doctors may order tests for scrub typhus and other causes of fever, and treatment may begin before laboratory results are available.
