Frequency and distribution of eschar in patients with scrub typhus in India: systematic review of literature and meta-analysis

Introduction: Scrub typhus is a mite-borne tropical febrile illness with high mortality if untreated. The presence of eschar is pathognomonic, but a wide range of frequencies of eschar positivity has been reported in Indian patients. Therefore, this systematic review and meta-analysis aimed to ascertain the frequency (overall and geographic region-wise) and anatomical distribution of eschar in scrub typhus in India. Methodology: We searched articles in two databases using: [(scrub OR typhus OR Orientia) AND (eschar) AND (India)]. The articles were independently screened and critically appraised by two authors. The frequency and distribution of eschar in patients with scrub typhus were pooled using a random-effect model. Results: After the title-abstract and full-text screening, 107 articles (34002 cases of scrub typhus) were finally included. The overall pooled proportion of eschar positivity was 28.5% (95% CI: 24.1 to 32.9%). The pooled eschar positivity varied from ≤12% in Haryana, Rajasthan, Madhya Pradesh, Punjab, and Meghalaya to ≥46% in Tamil Nadu and Tripura. The pooled proportion of eschar positivity in the ‘trunk’ (39.3%), ‘groin’ (23.8%), and ‘axilla’ (16.5%) was higher than in the ‘limbs’ (9.9%) and ‘head’ (11.3%). Conclusion: Eschar is reported in less than a third of the patients with scrub typhus in India. Most eschars were in the groin, axilla, and the trunk. There is a need to create awareness amongst physicians of the need for thorough physical examination.