Clinical characteristics of acute Q fever, scrub typhus, and murine typhus with delayed defervescence despite doxycycline treatment

Doxycycline is the recommended antibiotic for acute Q fever, scrub typhus, and murine typhus and defervescence often occurs within 3 days of treatment. Patients with delayed defervescence (> 3 days) are troublesome for clinicians. To investigate the characteristics of such patients, 18 and 88 cases with and without delayed defervescence, respectively, were studied. By univariate analysis, absence of headache (P = 0.004), jaundice (P = 0.030), icteric sclera (P = 0.030), relative bradycardia (P = 0.003), and pulmonary involvement on chest x-ray (P = 0.028) were significant findings in patients with delayed defervescence. By multivariate analysis, absence of headache (odds ratio [OR] = 8.310; 95% confidence interval [CI] = 1.990-34.706, P = 0.004), jaundice (OR = 6.242; 95% CI = 1.374-28.365, P = 0.018), and relative bradycardia (OR = 10.449; 95% CI = 2.137-51.088, P = 0.004) were the independent characteristics of patients with delayed defervescence. In treating acute Q fever, scrub typhus, and murine typhus with doxycycline, clinicians should be aware that delayed defervescence may occur in patients presenting with jaundice, relative bradycardia, and absence of headache.