Predictors of severity of scrub typhus in the Indian subcontinent

Objective: To identify the factors for predicting severity in scrub typhus which is an acute febrile illness caused by Orientia tsutsugamushi. Methods: A prospective study of 220 patients with scrub typhus was conducted at Kasturba hospital during May 2012 to April 2013, out of which 116 patients were in the severe disease group and 104 in the non-severe group. Results: Using univariate analysis, the presence of the following factors, namely age>40 years, haemoglobin<12 g/L, white blood cell count>10 000 cells/mm³, platelet<150 000 cells/mm³, albumin<3.5 g/dL and the absence of eschar were correlated with severe disease. However, on multivariate analysis, haemoglobin<12 g/dL (OR=2; P=0.037; CI=1.04-3.82); white blood cell count>10 000 cells/mm³ (OR=3; P=0.001; CI=1.5-5.8), platelet<150 000 cell/mm³ (OR=6.2; P<0.001; CI=3.1-12.4) and absence of eschar (OR=0.4; P=0.01; CI=0.2-0.8) were found to be predictors of severity. Conclusions: We conclude haemoglobin<12 g/dL, WBC count>10 000/mm³, platelet<150 000/mm³ and absence of eschar to be independent predictors of severity of illness in scrub typhus.