Clinical profile and risk factors associated with severe scrub typhus infection among non-ICU patients in semi-urban south India.

Background & Objectives: Scrub typhus is as an emerging infectious disease that generally causes acute febrile illness, with disease spectrum ranging from mild illness to multiorgan dysfunction. This study was aimed to report the clinical profile, complications and risk factors associated with severe illness in patients with scrub typhus, outside the intensive care setting.

Methods: It was a prospective study, which involved recruitment of patients with acute febrile illness and diagnosed to have scrub typhus, who were admitted to the general medical wards of a tertiary care centre in Kanchipuram district, in semi-urban south India, over a 12 month period between June 2015 and May 2016. The diagnosis was established both clinically (with or without pathognomonic eschar) and by a positive test of IgM antibodies against scrub typhus by ELISA. The severity of scrub typhus was determined by the presence of organ dysfunction, and the factors associated with it were analyzed.

Results: A total of 50 patients with mean age of 39.6±20.5 yr (mean ± SD) were admitted. The mean duration of illness before presentation was 9.10 ± 8.6 days. The mean duration of hospital stay was 7.7±3.6 days. The symptoms included fever, abdominal symptoms, headache, dysuria, breathlessness and altered sensorium. Most common findings on physical examination were eschar (58%), crepitations in the chest (36%), hepatomegaly (34%) and lymphadenopathy (30%). Thirty two percent had respiratory complications, 4% required mechanical ventilation, 24% had shock, 16% had acute kidney injury, and 6% had dysfunction of ≥2 organs. Age of >50 yr, longer duration of illness (>7 days), residence in a rural area and the absence of eschar were found to be independent risk factors for development of severe illness.

Interpretation & Conclusion: Severe scrub typhus infection among non-ICU patients is more likely to occur in elderly patients and in those with longer duration of illness prior to presentation. The subset of patients without eschar might be more prone to develop complications.