Mohan D Gupte1, Manish Gupte2, Suchit Kamble3, Arati Mane3, Suvarna Sane3, Vijay Bondre4, Jagadish Deshpande5, Deepak Gadkari6, Manoj V Murhekar7. 1. Indian Council of Medical Research, New Delhi, India. 2. Independent Scientist, Pune, India. 3. ICMR-National AIDS Research Institute, Pune, Maharashtra, India. 4. ICMR-National Institute of Virology, Gorakhpur Unit, Uttar Pradesh, India. 5. ICMR-Enterovirus Research Centre, Mumbai, Maharashtra, India. 6. Independent Virologist, Pune, India. 7. ICMR-National Institute of Epidemiology, Chennai, Tamil Nadu, India. Correspondence to: Dr Manoj V Murhekar, ICMR-National Institute of Epidemiology, Chennai, Tamil Nadu, India. mmurhekar@nieicmr.org.in.
Abstract
OBJECTIVE: To estimate the regional cutoff of optical density (OD) values for immuno-globulin M (IgM) antibodies against Orientia tsutsugamushi in serum and cerebrospinal fluid (CSF) for clinical diagnosis of scrub typhus and immunoglobulin G (IgG) antibodies in serum for sero-epidemiology in Gorakhpur, Uttar Pradesh, India. METHODS: We used data from a serological investigation of acute encephalitis syndrome patients (n=407) during the 2016 outbreak in Gorakhpur, India to determine the cutoff for OD values for IgM antibodies, and from community-based serosurveys (n=1991) to estimate the cutoff for OD values for IgG antibodies. RESULTS: We determined regionally relevant cutoff for OD values of 0.76 for IgM antibodies in serum and 0.22 in cerebrospinal fluid for scrub typhus diagnosis. For serosurveys, IgG antibody cutoff was 1.5. CONCLUSION: We have proposed locally relevant cutoffs for scrub typhus endemic regions, which may be useful for correctly classifying infected population.
OBJECTIVE: To estimate the regional cutoff of optical density (OD) values for immuno-globulin M (IgM) antibodies against Orientia tsutsugamushi in serum and cerebrospinal fluid (CSF) for clinical diagnosis of scrub typhus and immunoglobulin G (IgG) antibodies in serum for sero-epidemiology in Gorakhpur, Uttar Pradesh, India. METHODS: We used data from a serological investigation of acute encephalitis syndromepatients (n=407) during the 2016 outbreak in Gorakhpur, India to determine the cutoff for OD values for IgM antibodies, and from community-based serosurveys (n=1991) to estimate the cutoff for OD values for IgG antibodies. RESULTS: We determined regionally relevant cutoff for OD values of 0.76 for IgM antibodies in serum and 0.22 in cerebrospinal fluid for scrub typhus diagnosis. For serosurveys, IgG antibody cutoff was 1.5. CONCLUSION: We have proposed locally relevant cutoffs for scrub typhus endemic regions, which may be useful for correctly classifying infected population.