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Scrub Typhus is an acute febrile illness caused by the bacterium Orientia tsutsugamushi, transmitted to humans through the bite of infected chiggers (larval mites). It is part of the rickettsial group of diseases.

It is zoonotic and affects people working or living in areas with heavy vegetation such as forests, farms or scrubland — hence the name “scrub” typhus.

• Pathogen: Orientia tsutsugamushi

• Vector: Infected chigger mite (Trombiculid mites) larvae

• Reservoirs: Rodents and small mammals

• Mode of Transmission: Bite of infected chiggers during outdoor activity; not person-to-person.

Scrub typhus presents with non-specific flu-like symptoms, making diagnosis difficult. Common symptoms include:

• High fever (often > 102°F)

• Headache, body ache

• Rashes (maculopapular)

• Lymphadenopathy (swelling of lymph nodes)

• Eschar: A black scab at the site of the chigger bite (diagnostically significant)

• Fatigue, muscle pain

• Cough or respiratory symptoms

• In severe cases: multi-organ dysfunction, meningoencephalitis, ARDS, myocarditis

1. Clinical suspicion (especially if eschar is present)

2. Laboratory tests:

• ELISA for IgM antibodies (commonly used)

• IFA (Immunofluorescence Assay) – gold standard but expensive

• PCR (for confirmation in advanced labs)

• Weil-Felix test (obsolete, non-specific)

Antibiotics:

• Doxycycline – first-line treatment

• Azithromycin – preferred in pregnancy and children

• Chloramphenicol – alternative option

• Early treatment prevents complications and reduces mortality

• Avoiding grassy/scrub areas

• Protective clothing, insect repellents

• Rodent control in rural areas

• No vaccine available as of now

• Frequently reported in Himachal Pradesh, Uttarakhand, Tamil Nadu, Assam, Arunachal Pradesh and Northeast India.

• Himachal Pradesh has been a hotspot during monsoon seasons, with several outbreaks and fatalities reported (e.g. Kangra, Solan, Shimla, etc.).

• Often confused with dengue or leptospirosis in early stages.

• Part of the “tsutsugamushi triangle” – covers South and East Asia, northern Australia and the Pacific islands.

• Recent increase in global attention due to:

Climate change affecting vector spread

Co-infection cases with COVID-19

Under-reported due to low awareness and diagnostic limitations