Scrub Typhus in a Tertiary Care Hospital in Visakhapatnam

BACKGROUND Scrub typhus is a serious public health problem in the Asia-Pacific area including, India. It is a zoonotic disease and usually presents with acute febrile illness along with multi-organ involvement caused by Orientia tsutsugamushi. It is transmitted to humans by the bite of the larvae of trombiculid mites (Chiggers) which feed on forest and rural rodents. The mites are both vector and natural reservoir. Human infection follows a chigger bite. Incubation period is 6- 21 days. Onset of scrub typhus is characterised by fever, headache, myalgia, cough and gastrointestinal symptoms. A primary lesion which later crusts to form a flat black eschar may be present which is pathognomonic feature of scrub typhus. If the condition is not treated, serious complications may occur involving various organ systems. Owing to potential for severe complications, diagnosis and decision to initiate treatment should be based on clinical suspicion and confirmed by serological tests. The recommended treatment for scrub typhus is doxycycline. Our aim was to study the magnitude of scrub typhus antibodies among febrile patients for a period of one year in a tertiary care hospital and to assess clinical features and outcomes of serologically positive patients. METHODS Blood was collected aseptically from 131 patients with request for investigation of scrub typhus from various departments. Screening for scrub typhus was done by rapid Immunochromatographic test to identify antibodies. RESULTS During the 1-year study period, a total of 131 serum samples presenting with fever were tested for scrub typhus. Of these, 46 samples were found seropositive. Among these patients, Eschar was found only in 4.3% of cases. In one patient tuberculosis and in 3 patients dengue was found as co-infection. Seasonally the highest number of cases were observed in the cooler months of the year. Male to female ratio was not significant. The percentage of patients positive for scrub typhus was highest (17.6%) in the age group 16-25 years followed by (15.4%) in 26-35 year. None among the age group of 0-15 year was positive. CONCLUSIONS Prompt diagnosis, timely antimicrobial therapy and intensive supportive care are important to prevent life-threatening complications. Scrub typhus detected by immunochromatography can be utilized as part of initial investigation to guide the clinicians. In the present study we found that our results highlight that scrub typhus infection is an important cause of fever and active surveillance is necessary to access exact magnitude and distribution of the disease.