Chiggerosis (Scrub Typhus): A Growing Health Concern

Chiggerosis is a neglected but a widespread re-emerging vector borne zoonotic rickettsial infection. Which is caused by Orientia tsutsugamushi. This disease is spread by bite of larvae (chiggers) of Leptotrombidium mite. It was first observed in Japan. This disease is endemic to a geographically distinct region, so called tsutsugamushi triangle. In recent years its geographic range is growing as well as prevalence of the disease is increasing across the globe due to various factors, which is a matter of concern.

WHO has declared this to be one of the most underdiagnosed diseases worldwide that often necessitates hospitalization. Clinical picture consists of high-grade fever, severe headache, myalgia, dry cough, lymphadenopathy, maculopapular rash and hearing problem. A necrotic eschar at the inoculating site of the mite is pathognomic of scrub typhus (present in 10% to 50% of patients). Incubation period is 1 to 3 weeks. It is generally seen in people whose occupational or recreational activities bring them into contact with ecotypes favourable with vector chiggers. Patients may develop complication like pneumonia, meningoencephalitis, myocarditis and renal failure, if they left untreated or delay in diagnosis.

Among all available test IgM Elisa is the test of choice. Public health importance of this disease is underestimated because of difficulty in the clinical diagnosis and lack of the laboratory methods in many geographical areas. So, exact incidence of the disease is unknown. Studies reveal that proportion of Scrub typhus among patients of AUFI is 25.3%. The average community seroprevalence is 34.2%. The highest case densities are from Tamil Nadu, Himachal Pradesh, Karnataka and Uttarakhand in India. Case fatality is 7% which can be up to 30% in patients who have complication like ARDS, Myocarditis, acute renal failure and multi organ failure. Close suspicion of the disease along with the increased use of affordable and accurate test, is mandatory to improve diagnosis and treatment of this condition which can be easily treated with antibiotics. In recent years azithromycin and doxycycline are being used in treatment. No vaccine is available to prevent Scrub typhus till now.