Scrub typhus is endemic in India. Right now scrub typhus is enjoying its status as a re-emerging disease and is often causing trouble in diagnosis due to absence of specific rash or eschar. In our institution, we observed a seasonal rise of febrile illnesses that coincided with monsoon rain, and decided to investigate the probable etiological role of scrub typhus among the undiagnosed fever cases. This prospective study was conducted from the middle of May to the end of August in 2019. All febrile patients who tested negative for malaria, dengue, urinary tract infections, enteric fever and other pyogenic infections were included in this study. Those who became serologically reactive for Scrub typhus IgM antibody by ELISA were considered as established cases of scrub typhus. The seroprevalence of scrub typhus among undiagnosed fever cases was 33.9% with a resultant mortality of 11.8%. Fever (100%), headache (92%) and myalgia (62%) were the commonest symptoms followed by lymphadenopathy, vomiting, diarrhea, pain abdomen, rash and rarely eschar. Meningoencephalitis (12%) was the commonest complication followed by acute kidney injury which along with hepatitis often led to fatal multi organ failure. Thus, scrub typhus should be considered at the earliest in the differential diagnoses for acute undiagnosed fever with nonspecific features in endemic countries like ours.

Keywords: Scrub typhus, IgM ELISA, undiagnosed fever, non-specific features, meningoencephalitis.

1. Chunchanur Sk. Scrub Typhus in India- an impending threat! Ann Clin Immunol Microbiol. 2018;1,(1):1003 tropical med 3010011
2. Ju Jiang, Allen L. Richards. Scrub Typhus: No longer restricted to the Tsutsugamushi triangle. Trop Med Infect Dis. 2018,3,11; doi: 10.3390/tropicalmed3010018
3. Alison Luce-Fedrow, Marcie L.Lehman, Daryl J. Kelly, et al. A Review of Scrub Typhus (Orientiatsutsugamushi and Related Organisms): Then, Now and Tomorrow. Trop Med Infect Dis. 2018, 3(1),8; doi:10.3390/tropicalmed3010008
4. Varghese GM, Trowbridge P, Janardhanan J, et al. Clinical profile and improving mortality trend of scrub typhus in South India. Int J Infect Dis. 2014 Jun;23:39-43.doi:10.1016/j.ijid.2014.02.009.Epub 2014 Mar 21
5. Mahajan SK, Rolain JM, Kashyap R, et al. Scrub typhus in Himalayas. Emerg Infect Dis. 2006;12: 1590-2
6. Chrispal A, Boorugu H, Gopinath KG et al. Scrub typhus: an unrecognised threat in South India- clinical profile and predictors of mortality. Trop Doc.2010;40: 129-33
7. Batra HV. Spotted fever and typhus fever in Tamil Nadu. Indian J Med Res. 2007; 126: 101-3
8. Chakraborty S, Sarma N. Scrub typhus: An emerging threat. Indian J Dermatol. 2017; 62: 478-85
9. Watt G., Parola P, Scrub typhus and tropical rickettsioses. Curr Opin infect Dis. 2003;16: 429-436
10. Sharma PK, Ramakrishnan R, Hutin YJ, et al.Scrub typhus in Darjeeling, India: Opportunities for simple, practical prevention measures. Trans R Soc Trop Med Hyg. 2009; 103v:1153-8. 
11. Ray Laskar A, Suri S, Acharya AS. Scrub Typhus: Re-emerging Public Health Problem in India. J Dis. 2015; 47 (3):19-25.
12. Thomas R, Puranik P, Kalal B et al. Fie-year analysis of rickettsial fevers in children in South India: Clinical manifestations and complications, J Infect Dev Ctries.2016;10 (6): 657-61
13. Li T, Yang Z, Dong Z, et al. Meteorological factors and risk of scrub typhus in Guangzhou, sothern China, 2006-12. BMC infect Dis.2014; 14:139
14. Mathai E, Rolain JM, Verghese GM, et al. Outbreak of Scrub typhus in Southern India during cooler months. Ann NY Acad Sci.20003;990:359-64
15. Vivekanandan M, Mani A, Priya YS et al. Outbreak of scrub typhus in Pondicherry. J Assoc Physicians India.2010; 58: 24-8
16. Kim DM, Won KJ, Park CY et al. Distribution of eschars on the body of scrub typhus patients: a prospective study. Am J Trop Med Hyg.2007;76:806-9
17. Varghese GM, Abraham OC, Mathai D, et al. Scrub typhus among hospitalised patients with febrile illness in South India: magnitude and clinical predictors. J  2006; 52:56-60
18. Kumar K, Saxena VK, Thomas TG, et al. Outbreak investigation  of scrub typhus in Himachal Pradesh (India). J Commun Dis 2004; 36:277-83
19. Attur RP, Kuppasami S, Bairy M, et al. Acute kidney injury in scrub typhus.  2013; 17:725-29
20. Peter JV, Sudarshan TI, Prakash JAJ, et al. Severe scrub typhus infection: Clinical features, diagnostic challenges and management. World J Crit Care Med. 2015 Aug 4; 4(3): 244-250.

Dr Purba Mukherjee

Assistant Professor, Department of Microbiology, Calcutta National Medical College, Kolkata