A hepatitis C avidity test for determining recent and past infections in both plasma and dried blood spots.

BACKGROUND: DBS testing has been used successfully to detect HCV antibody positive individuals. Determining how long someone has been infected is important for surveillance initiatives. Antibody avidity is a method that can be used to calculate recency of infection. OBJECTIVES: A HCV avidity assay was evaluated for both plasma and DBS. STUDY DESIGN: To measure antibody avidity a commercial HCV ELISA was modified using 7 M urea. The plasma samples were split into: group 1 (recently infected N = 19), group 2 (chronic carrier N = 300) and group 3 (resolved infection N = 82). Mock DBS made from group 1 (N = 12), group 2 (N = 50), group 3 (N = 25) and two seroconverter panels were evaluated. 133 DBS taken from patients known to have a resolved infection or be a chronic carrier were also tested. RESULTS: The avidity assay cut-off was set at AI≤30 for a recent infection. Using sequential samples the assay could detect a recent infection in the first 4-5 months from the point of infection. Most of the false positive results (AI < 30 among cases known not to have had recent infection) were detected among known resolved infections, in both the plasma and DBS; as a result, a testing algorithm has been designed incorporating both PCR and two dilution factors. The sensitivity and specificity of the assay on plasma was 100% and 99.3%, respectively, while DBS had 100% sensitivity and 98.3% specificity. CONCLUSION: The HCV avidity assay can be used to distinguish between chronic and recent infection using either plasma or DBS as the sample type.

Decrease in health-related quality of life associated with awareness of hepatitis C virus infection among people who inject drugs in Scotland.

BACKGROUND & AIMS: Chronic hepatitis C virus (HCV) infection can significantly reduce health-related quality of life (QoL), but it is not clear if reduction is associated with the infection or with being aware of one's infection status. Understanding the impact of a HCV diagnosis on QoL is essential to inform decision-making regarding screening/testing and treatment. METHODS: Using a cross-sectional design, we assessed QoL in 2898 people who inject drugs (PWID), surveyed in Scotland during 2010 using EQ-5D. Multifactorial regression compared self-reported QoL between PWID who were (i) chronically HCV-infected and aware of their infected status, (ii) chronically HCV-infected but unaware, and (iii) not chronically infected. RESULTS: Median time since onset of injecting was 10years; not chronically infected PWID were younger and had shorter injecting careers than chronically infected PWID. Median EQ-5D was highest for the not chronically infected and the chronic/unaware groups (0.73) compared with the chronic/aware group (0.66). After adjustment for demographic and behavioural co-factors, QoL was significantly reduced in chronic/aware compared with chronic/unaware PWID (adjusted B=-0.09, p=0.005); there was no evidence for a difference in QoL between not chronically infected and chronic/unaware PWID (adjusted B=-0.03, p=0.13). CONCLUSIONS: Awareness of one's chronic HCV status was associated with reduced health-related QoL, but there was no evidence for further reduction attributable to chronic infection itself after adjusting for important covariate differences.

Examination of the risk of reinfection with hepatitis C among injecting drug users who have been tested in Glasgow.

BACKGROUND: Unsafe injecting practices put injecting drug users (IDUs) at repeat exposure to infection with the hepatitis C virus (HCV). It has not yet been determined if spontaneously clearing one's primary infection influences the risk of reinfection; our aim was to estimate the relative risk of reinfection in IDUs who have cleared the virus. METHODS: We conducted a retrospective study using a large database of HCV test results covering Greater Glasgow Health Board during 1993-2007 to calculate rates of infection and reinfection in current/former IDUs. The relative risk of (re)infection in previously infected compared with never-infected IDUs was estimated using Poisson regression, adjusting for age at study entry, sex, and calendar period of test. RESULTS: Although the rate of reinfection in IDUs who were HCV antibody-positive, RNA-negative at baseline was lower (7/100 person-years, 95% CI: 5-9) than the rate of acute infection in IDUs who were HCV antibody-negative at baseline (10/100 person-years, 95% CI: 9-12), the risk of reinfection was not significantly different than the risk of initial infection (adjusted rate ratio=0.78, 95% CI: 0.57-1.08). CONCLUSION: We found only weak evidence for a reduced risk of HCV reinfection in IDUs who had cleared their previous infection. Further research among those who have cleared infection through antiviral therapy is needed to help inform decisions regarding treatment of IDUs.

Detection of hepatitis C virus RNA in dried blood spots.

BACKGROUND: An estimated 130-170 million people worldwide are chronically infected with HCV.(1) In Europe the highest prevalence of HCV infections is in the IDU population.(2) As traditional HCV screening relies on the detection of HCV antibody or HCV RNA in blood, screening in high-risk groups such as IDU is difficult due to poor venous access caused by damaged veins. OBJECTIVES: In this study DBS was evaluated as an alternative sample type to blood for the detection of HCV RNA. STUDY DESIGN: The endpoint detection limit, inter-assay and intra-assay variability of the method were determined. The DBS method was compared to our routine frontline assay using a panel of paired DBS and blood samples. The effect of different storage temperatures and length of storage time on the stability of HCV RNA in DBS was also assessed. RESULTS: The endpoint detection limit of the method based on results from mock DBS was 250 IU/ml. The method was shown to be precise and robust. The sensitivity and specificity of the method was found to be 100% and 95.8%, respectively. No significant variation in the stability of HCV RNA in DBS over a 1 year period at a range of different temperatures was observed. CONCLUSIONS: A sensitive and stable method was developed for the detection of HCV RNA in DBS. Screening high-risk populations using DBS as a sample type may improve uptake of HCV testing by increasing opportunity for patients to be tested and consequently increasing access to treatment.

Trends in the incidence of HIV in Scotland, 1988-2009.

OBJECTIVES: To estimate temporal trends in HIV incidence and prevalence in Scotland, according to three main risk groups for infection: men who have sex with men (MSM), injecting drug users (IDUs) and heterosexuals. METHODS: The authors extracted data for all single- and multiple-tested individuals from the national HIV test database covering the period 1980-2009 and calculated the incidence of HIV infection in each risk group and estimated RRs by fitting Poisson regression models. RESULTS: 620 of 59,807 individuals tested positive following an initial negative HIV test, generating an overall incidence rate of 3.7/1000 person-years (95% CI 3.4 to 4.0); 60%, 20% and 37% of the 620 were associated with the risk behaviour categories MSM, IDU and heterosexual, respectively. The incidence rate among MSM in Scotland remained relatively stable between the periods <1995 and 2005-2009 (overall: 15.3/1000 person-years, 95% CI 13.8 to 17.0), whereas the incidence among IDUs decreased between the periods <1995 and 2005-2009, from 5.1/1000 to 1.7/1000 person-years, and also decreased among heterosexuals, from 2.9/1000 to 1.4/1000 person-years. CONCLUSIONS: The reduction in the incidence rate among IDUs suggests that harm reduction measures initiated from the late 1980s were effective in reducing HIV transmission in this risk group; however, the absence of a reduction in HIV incidence rates among MSM is disappointing and highlights the need for renewed efforts in the prevention of HIV in this major risk group.

The use of the OraSure collection device for hepatitis virus testing in health care settings.

Oral mucosal transudate (OMT) has levels of IgG and IgA that, although lower than in serum, are of the same specificity as serum. Blood can be a difficult sample to take especially from persons with an aversion to the process or with poor veins. There is also a small exposure risk to the phlebotomist. OMT has been shown to be useful in screening for a range of bloodborne viruses, however, the ELISA assays need to be modified, usually by increasing test volumes and incubation times and/or by modifying the substrate. A number of commercial serum kits have been modified successfully in this way. The major roles for these assays are for epidemiology or for screening high risk populations. If used for screening, it is imperative that any positive is confirmed by a serum test. The use of OMT samples using the OraSure(R) collection device, which is FDA approved and with which we have the most experience, has increased in recent years in community health care settings, with positive feedback from users.