Seroprevalence trends of Scrub typhus among the febrile patients of Northern India

BACKGROUND: Rickettsial infections remain one of the most neglected and underdiagnosed tropical diseases in the developing countries. Scrub typhus can prove to an important diagnosis in pyrexia of unknown origin (PUO) patients and is transmitted by a species of trombiculid mites ("chiggers"). The disease leads to a plethora of symptoms like fever, rash, headache, nausea, abdominal pain, thrombocytopenia, etc. The current study was aimed to assess the seroprevalence as well as other demographic parameters of scrub typhus among patients diagnosed with PUO in the northern part of India. MATERIALS AND METHODS: This study was undertaken for a period of 3 years from September 2017 to September 2020. Serum samples of suspected cases were tested for IgM Scrub typhus along with other common febrile illnesses like Malaria, typhoid, dengue, leptospirosis, chikengunya, etc. Additional testing for COVID-19 was also planned for samples received after February 2020. RESULTS: The overall seroprevalence of Scrub typhus during the 3 year study period was noted to be 18.6% in the PUO patients. Typhoid was noted in 39.5%, malaria in 9.2%, Dengue in 13.5%, leptospirosis in 4.8%, and chikungunya in 5.3% of the patients. No cause was identified in 9.1% of the PUO cases. 3.9% of the samples were positive by RT-PCR for COVID-19. No mortality was noted in the scrub typhus positive cases. CONCLUSION: Scrub typhus is an emerging tropical rickettsial disease in the Indian subcontinent. The present study highlights the importance of screening of PUO cases for this important infection as timely institution of simple empirical treatment can prove to be life saving in such positive cases.