Three years of data from Gorakhpur’s Baba Raghav Das (BRD) Medical College has confirmed that the majority of Acute Encephalitis Syndrome (AES) patients admitted to the hospital between August and October each year have scrub typhus. This finding is important, given that scrub typhus can be treated easily if detected early. The first indication of scrub typhus’ role came during a 2014 study at BRD by researchers from Karnataka’s Manipal Centre for Viral Research. But there was much scepticism about this hypothesis then.
In the following years, however, other researchers reported similar findings. In 2015, a team led by the director of Chennai’s National Institute of Epidemiology, Manoj Murhekar, found that out of 370 AES patients tested during September-October, 63% had antibodies to scrub typhus. The findings were reported in the Journal of Infection . In 2016, out of 407 AES patients during the same period, 65% had the illness.
Also, when all AES patients were given azithromycin, a treatment for scrub typhus, 35% of non-scrub-typhus patients died, while only 15% of scrub patients died, indicating that azithromycin was effective. These findings were published in the Pediatric Infectious Disease Journal in May this year. Finally, in 2017, over 50% of patients admitted to BRD in August-September were positive for scrub typhus, according to data shared with The Hindu by the Indian Council of Medical Research.
Study of mites
Further evidence for the role of scrub typhus comes from a study of trombiculid mites in eastern Uttar Pradesh by Chennai’s Vector Control Research Centre (VCRC). They found that the mites carried Orientia tsutsugumashi, the bacterium which causes scrub typhus. While this study was published in Vector Borne and Zoonotic Diseases in July 2018, P. Jambulingam, VCRC Director, also told The Hindu that unpublished research has shown an increase in infestation of rodents by trombiculid mites during August-October. This explains why scrub typhus incidence peaks during monsoon, he said.