Scrub Typhus

Scrub typhus is a severe infectious disease caused by the rickettsial bacterium, which displays high levels of antigenic variation. The disease is a serious public health concern in the Asia-Pacific region, including, but not limited to, the region known as the "tsutsugamushi triangle." Spanning over 8 million square kilometers and affecting more than 1 billion people across countries such as Pakistan in the west, Australia in the south, and Japan in the east, this triangular area poses a significant public health threat with a high risk of fatality.  A systemic review on the burden of scrub typhus in India, located within the "tsutsugamushi triangle," revealed that scrub typhus accounts for at least 25.3% of individuals with acute undifferentiated febrile illness. Despite being one of the common pathogens of the cause of such encountered illness, scrub typhus remains a neglected disease in terms of research and healthcare policy formulation. The infection is transmitted to humans through the bite of larval trombiculid mites, leading to disseminated vasculitis, perivascular inflammation, vascular leakage, and end-organ injury. Travelers to endemic regions and individuals of all ages are susceptible to this disease. Clinical features usually arise after an incubation period of 6 to 21 days and manifest as fever, headache, myalgia, and gastrointestinal symptoms. An "eschar" is a distinct characteristic of scrub typhus, which generally begins as a primary papular lesion at the site of the bite. However, it may later crust to form a black ulcer with central necrosis. However, the presence of the eschar may vary by region. The decision to initiate treatment should be based on clinical suspicion and later confirmed by serological tests.