Comparison of ELISA and dual stage real time RT-PCR to differentiate Sabin like and non-Sabin like poliovirus isolates.

Environmental surveillance of polioviruses has been used as an important tool in monitoring circulation of wild polioviruses and/or Vaccine derived polioviruses in sewage samples. It is important to distinguish Sabin like isolates from non-Sabin like; ELISA & dual stage real time RT-PCR have been used for the same. Current study was carried out on sewage isolates to compare ELISA & RT-PCR with sequencing to distinguish Sabin like from non-Sabin like. Out of 468 sewage specimens, 91 (19.44%) were non-polio enteroviruses positive and 377 (80.56%) were polio positive by virus isolation method. A total of 488 polio virus isolates were detected by L20B and RD route which were further subjected to ELISA and RT-PCR. The results were compared with sequencing. On comparison, the specificity of ELISA was only 66.67% in spite of very low sensitivity (3.43%). The sensitivity of RT-PCR was 97.71% which makes it a good primary screening test for detection of non-Sabin like viruses. However, the specificity was only 33.33%. RT-PCR appears to be a sensitive tool for detecting non-Sabin like viruses however; the isolates which are non-Sabin like by RT-PCR may not necessarily be mutated viruses. ELISA cannot be used for differentiation of Sabin likes from non-Sabin likes due to low sensitivity.

Environmental surveillance of polioviruses with special reference to L20B cell line.

With the eradication of poliovirus, the focus has now shifted to environmental surveillance of poliovirus to determine the circulating polioviruses in an area. L20B and RD cell lines are used for isolation of polioviruses. It is imperative to study the efficacy of these cell line in isolating polioviruses from environmental samples. The present study was carried out to determine the sensitivity and specificity of L20B cell line for isolation of polioviruses from environmental samples. L20B and RD cell lines are used for isolation of polioviruses. Molecular characterization was done by using real time RT-PCR. A total of 432 sewage samples from Delhi and Punjab were processed for the isolation of polioviruses during Jan-Dec 2015. 96.76% of the samples were positive in either of the cell lines. Non-polio enteroviruses were obtained in 50 samples on primary isolation. On RT-PCR, 347 (94.29%) samples yielded polioviruses and the rest (21) non-polio enteroviruses or non-enteroviruses. A total of 703 isolates were obtained. 635 isolates were found polioviruses by PCR (90.33%), 20 isolates were found to be NPEV (2.84%) and 48 (6.83%) were found to be NEV. Out of the 20 NPEV isolates, 14 were from RLR (RD-L20B-RD) route and six isolates were from LR (L20B-RD) route. All 48 NEV isolates were from LR route. Thus L20B cell line is more sensitive as compared to RD cell line for isolation of polioviruses however it is not absolutely specific for polioviruses.

Molecular epidemiological analysis of three hepatitis C virus outbreaks in Jammu and Kashmir State, India.

Outbreaks of hepatitis C virus (HCV) infection are associated with unsafe injection practices, intravenous drug abuse and other exposure to blood and body fluids. We report here three outbreaks of HCV infection from Jammu and Kashmir (J&K) State, India, which occurred over a period of 3 years and in which molecular epidemiological investigations identified a presumptive common source of infection, most likely a single healthcare venue. Representative blood samples collected from cases of hepatitis C were sent to the National Centre for Disease Control (NCDC) for molecular characterization. These samples were positive by HCV ELISA. Subsequently, specimens were also tested for the presence of HCV RNA by RT-PCR. Sequencing was carried out for all positive samples. A total of 812 cases were laboratory confirmed by HCV ELISA; a total of 115 samples were sent to the NCDC for RT-PCR, and 77 were positive. Subtype 3a of HCV was found in all samples from Anantnag (February 2013); and for subtype 3b, in all samples from Srinagar (May 2015). Subtypes 3a and 3g were identified from two samples from the Kulgam outbreak (July 2014). A detailed epidemiological investigation should be conducted whenever a cluster of HCV cases is revealed, as this potentially allows for the identification of larger outbreaks. Epidemiological investigations of outbreaks should be further supported by inclusion of molecular tests. Efforts to limit therapeutic injections to only those cases having strong medical/surgical indications and to restrict the use of non-sterile needles are essential to prevent transmission of HCV.

Crucial factors that influence cost-effectiveness of universal hepatitis B immunization in India.

This study examines the parameters crucial to cost-effectiveness of universal hepatitis B immunization in India. An incremental cost-effectiveness analysis was done using a decision tree (Markov model) to follow up a hypothetical cohort of 100,000 newborns for the effects of hepatitis B acquired vertically at birth. The measure of effectiveness was disability-adjusted life-years gained. Uncertainty analysis and Scenario analysis were done using Latin hypercube sampling. Hepatitis B endemicity is the most important factor, followed by the cost of vaccine. Other factors of some influence are vaccination coverage, vaccine efficacy, HBeAg positivity, and vaccine wastage.