Prospective study to assess the treatment modalities and fever defervescence in patients with scrub typhus from a tertiary care centre in South India.

Background and objectives: Fever defervescence in scrub typhus, a zoonotic bacterial infection is used as a surrogate marker of disease resolution. Failure of fever defervescence prompts clinicians to suspect alternate diagnoses and treatment. In this observational study, various treatment regimens were correlated with clinical outcomes. Methods: All adult patients with a diagnosed scrub typhus were included; various antibiotic regimens used and clinical outcomes were studied. Data was analyzed using SPSS software for windows 16, with a 2-sided P-value of 0.05 or less was considered statistically significant. Results: In 177 hospitalized patients with scrub typhus, combination therapy (doxycycline and azithromycin) was used in 74 subjects with doxycycline and azithromycin used in 46 and 57 subjects, respectively. Incidence of delayed defervescence was seen in 31.6%, Combination therapy being preferred in sicker patients (SOFA score 8.82). Presence of respiratory dysfunction was associated with a delay in fever defervescence [risk ratio 2.50(1.18-5.3)]. Patients receiving doxycycline did better in terms of oxygen requirement and the presence of hypotension. The overall case fatality rate was 5.6%. The severity of illness rather than the choice of antibiotics predicted the outcome in scrub typhus. Interpretation & conclusion: Combination therapy with doxycycline and azithromycin is the most common regimen used. Incidence of delayed defervescence (31.6%) is increasing despite therapy and the involvement of respiratory dysfunction is an independent predictor of delayed fever defervescence.