Scrub typhus causing acute undifferentiated febrile illness and its association with clinical outcomes: An observational hospital based study from tertiary care center in North India

Abstract

Background: The clinical presentation of Scrub typhus mimics other acute undifferentiated febrile illnesses (AUFI) thus making it difficult to diagnose clinically. Methods: Patients hospitalized with acute febrile illness (2-21 days) along with clinical suspicion for scrub typhus were evaluated for specific IgM antibodies against O. tsutsugamushi by ELISA and details of demographic, clinical, laboratory and clinical complication/outcomes related parameters collected for statistical analysis. Results: Scrub typhus IgM antibodies by ELISA were detected in 88 (18.1%) patients out of 486 patients hospitalized with acute febrile illness and clinically suspected for Scrub typhus between September 2015 and January 2017. The majority sero-positive cases were found in July-December (p=0.02). Out of 88, twenty nine sero-positive Scrub typhus patients had serological evidence of co-infections. Eschar was observed in 11 (12.5%) sero-positive patients. Of 88, 23 sero-positive Scrub typhus patients died. A low platelet count (RR: 0.99; 95% CI:0.98-1.00, p=0.02), requirement of intensive care (RR: 2.26; 95% CI: 0.19-26.5, p = 0.01), need for mechanical ventilation (RR: 3.8, 95% CI: 1.35-10.86, p =0.003) and metabolic acidosis (RR: 3.47; 95% CI: 0.9-13.4, p = 0.03) were associated with mortality among sero-positive Scrub typhus patients. An appropriate antibiotic administration (n=46/88) was associated with clinical recovery/discharge (n=42/46; p=0.002). Conclusion: Our results emphasize early diagnosis and administration of appropriate antibiotic for the management of scrub typhus in view of multiple etiologies in the initial diagnostic workup of patients presenting with AUFI. Thrombocytopenia, metabolic acidosis, need for mechanical ventilation and intensive care were associated with adverse clinical outcome among patients with Scrub typhus.