A STUDY ON THE DIAGNOSTIC METHODS OF SCRUB TYPHUS COMPARITIVELY

Scrub typhus is one of the causes of acute undifferentiated fever. During the study period from October 2012 to August 2014, a total of 633 cases of suspected Scrub typhus presented to our hospital. Out of these, 95 serum samples were positive for scrub typhus either by Weil Felix or by ELISA (IgM antibody to Orientia tsutsugamushi). Predominant clinical feature was fever with an average of 10 days followed by headache, vomiting, cough, myalgia, breathlessness, loose stools, reduced urine output, abdominal pain and nausea. Eschar was observed in 6 out of the 95 patients (6.3%) in our study. The percentages of patients with Scrub typhus having eschars were variable with different studies citing different results. In our study we observed an almost equal incidence of Scrub typhus in both genders. Other studies showed variable reports with some showing male predominance and others showing female predominance. Maximal incidence of Scrub typhus according to our study was in the age group 41 – 50 yrs with decreasing incidence as one goes further from this peak to either side. Increased numbers of Scrub typhus cases were observed from September to February, which coincided with the cooler months of the year. Scrub Typhus diagnosis is made more complex by the presence of dual infections. Dual infections should be suspected when the patients present with atypical clinical features of either disease or when patient responds poorly to treatment. The platelet levels were low in Scrub typhus, but it was lower when the patient was infected with both Scrub typhus and Dengue infection. Main stay of Scrub typhus diagnosis remains serology. The gold standard for the diagnosis is Indirect Fluorescence Antibody assay. Both Weil Felix and ELISA tests were done and compared with IFA in 100 samples. The sensitivity of Weil Felix OX K at a break point of 1:160 was found to be 40% and specificity 94%, Positive predictive value was 86.9% and negative predictive value 61.0%. The ELISA tests showed sensitivity to be 96% and specificity 88%, Positive predictive value was 88.8% and negative predictive value 95.6 %. All currently available serological methods have their limitations. There is an urgent need for newer diagnostic methods. The treatment given is Doxycycline or azithromycin. Most of our cases responded to these drugs except one case where combination therapy was attempted. Scrub typhus responds well to treatment and if not treated in time the patient can go in for complications emphasizing the need for early diagnosis and treatment.