Expansion of the measles and rubella laboratory network, India.

Objective: To expand the measles and rubella laboratory network of India by integrating new laboratories. Methods: In collaboration with the World Health Organization (WHO), the Indian government developed a 10-step scheme to systematically expand the number of laboratories performing serological and molecular testing for measles and rubella. The Indian Council of Medical Research and WHO identified suitable laboratories based on their geographical location, willingness, preparedness, past performance and adherence to national quality control and quality assurance mechanisms. The 10-step scheme was initiated with training on measles and rubella diagnostic assays followed by testing of both measles and rubella serology and molecular unknown panels, cross-verification with reference laboratories and ended with WHO on-site accreditation. Findings: After extensive training, technical support, funding and monitoring, all six selected laboratories attained passing scores of 90.0% or more in serological and molecular proficiency testing of measles and rubella. Since 2018, the laboratories are a part of the measles and rubella network of India. Within 12 months of initiation of independent reporting, the six laboratories have tested 2287 serum samples and 701 throat or nasopharyngeal swabs or urine samples. Conclusion: The process led to strengthening and expansion of the network. This proficient laboratory network has helped India in scaling up serological and molecular testing of measles and rubella while ensuring high quality testing. The collaborative model developed by the Indian government with WHO can be implemented by other countries for expanding laboratory networks for surveillance of measles and rubella as well as other infectious diseases.

Detection of Immunoglobulin M and Immunoglobulin G Antibodies Against Orientia tsutsugamushi for Scrub Typhus Diagnosis and Serosurvey in Endemic Regions.

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.

Rapid disease progression in human immunodeficiency virus type 1-infected seroconverters in India.

To determine if the early immunological and virological events of HIV infection are unique in a setting with limited access to health care and HIV-1 subtype C infection, we undertook a prospective cohort study to characterize the early natural history of HIV viral load and CD4(+) T lymphocyte counts in individuals with recent HIV seroconversion in India. CD4(+) T lymphocyte counts were prospectively measured for up to 720 days in 46 antiviral drug-naive persons with very early HIV infection, documented by HIV antibody seroconversion. HIV viral RNA levels were measured subsequently on reposited plasma samples from these same time points. The median viral load "set point" for Indian seroconverters was 28,729 RNA copies/ml. The median CD4(+) cell count following acute primary HIV infection was 644 cells/mm(3). Over the first 2 years since primary infection, the annual rate of increase in HIV viral load was +8274 RNA copies/ml/year and the annual decline in CD4 cell count was -120 cells/year. Although the viral "set point" was similar, the median trajectory of increasing viral load in Indian seroconverters was greater than what has been reported in untreated HIV seroconverters in the United States. These data suggest that the more rapid HIV disease progression described in resource-poor settings may be due to very early virological and host events following primary HIV infection. A rapid increase in viral load within the first 2 years after primary infection may have to be considered when applying treatment guidelines for antiretroviral therapy and opportunistic infection prophylaxis.