Scrub Typhus Emerges as Leading Infectious Cause of Acute Encephalitis Syndrome in Southern India

Bengaluru, July 18, 2025 — New research highlights a concerning trend in southern India: Scrub typhus, a mite-borne bacterial infection, has rapidly become the most common infectious cause of Acute Encephalitis Syndrome (AES) among children in the region. This revelation has important implications for clinical diagnosis, public health responses, and rural healthcare infrastructure.

What is Scrub Typhus?

• Scrub typhus is caused by the bacterium Orientia tsutsugamushi and is transmitted to humans through the bite of infected larval mites, commonly known as chiggers.

• The disease is endemic in the so-called “tsutsugamushi triangle,” which encompasses parts of Asia, including large areas of India.

• Common symptoms include high fever, headache, muscle pain, rash, and swelling of lymph nodes. In severe cases, it can lead to acute respiratory distress, organ dysfunction, and neurological complications such as AES.

Findings from Southern India

• Recent systematic investigations in major hospitals across southern India, including Karnataka and Andhra Pradesh, have indicated that scrub typhus now accounts for a significant proportion of AES cases in children.

• In one pivotal study, scrub typhus was diagnosed in about 23% of pediatric AES admissions, overtaking more well-known causes such as viral infections.

• Neurological complications were observed in 20–25% of scrub typhus patients who were hospitalized, with a noteworthy percentage requiring intensive care or ventilatory support.

The Diagnostic Challenge

• AES has multiple potential causes, many of them viral (e.g., Japanese encephalitis virus), making clinical diagnosis complex.

• Laboratory tests, especially IgM and PCR for scrub typhus, are key in confirming the causative agent. Testing cerebrospinal fluid has shown promising sensitivity and specificity rates, facilitating better diagnosis.

• Routine screening for scrub typhus is being recommended for all cases of AES in affected regions, given its status as a treatable infection when diagnosed early.

Public Health Implications

• Scrub typhus remains under-recognized in rural communities, despite diagnostic availability at major hospitals.

• Experts emphasize the importance of public awareness, community-based surveillance, and wider access to diagnostic tools, particularly in high-risk periods and areas with dense vegetation and rural populations.

• Scrub typhus is highly treatable with antibiotics such as doxycycline, but delayed diagnosis can lead to severe complications and fatalities.

Expert Opinions

Researchers and clinicians are urging policymakers to intensify surveillance of scrub typhus and incorporate routine testing into all cases of AES. “Our findings suggest scrub typhus as an emerging common treatable cause of AES in children in southern India and highlight the importance of routine testing,” a study concluded.

Prevention and Awareness

• Avoiding exposure to grassy and scrubby areas where chigger mites dwell.

• Using protective clothing and repellents when in risk-prone environments.

• Timely consultation with healthcare providers if symptoms arise, particularly during the monsoon and post-monsoon months, when cases surge.

Disclaimer:
This article is based on current research and available medical literature as of July 2025. It is intended for informational purposes only and should not be substituted for professional medical advice, diagnosis, or treatment. For any health concerns, please consult a qualified healthcare provider.