Molecular methods of measurement of hepatitis B virus, hepatitis C virus, and human immunodeficiency virus infection: implications for occupational health practice

Mapping the Scientific Research on Healthcare Workers' Occupational Health: A Bibliometric and Social Network Analysis

In the last few years, the occupational health (OH) of healthcare workers (HCWs) has been shown increasing concern by both health departments and researchers. This study aims to provide academics with quantitative and qualitative analysis of healthcare workers’ occupational health (HCWs+OH) field in a joint way. Based on 402 papers published from 1992 to 2019, we adopted the approaches of bibliometric and social network analysis (SNA) to map and quantify publication years, research area distribution, international collaboration, keyword co-occurrence frequency, hierarchical clustering, highly cited articles and cluster timeline visualization. In view of the results, several hotspot clusters were identified, namely: physical injuries, workplace, mental health; occupational hazards and diseases, infectious factors; community health workers and occupational exposure. As for citations, we employed document co-citation analysis to detect trends and identify seven clusters, namely tuberculosis (TB), strength training, influenza, healthcare worker (HCW), occupational exposure, epidemiology and psychological. With the visualization of cluster timeline, we detected that the earliest research cluster was occupational exposure, then followed by epidemiology and psychological; however, TB, strength training and influenza appeared to gain more attention in recent years. These findings are presumed to offer researchers, public health practitioners a comprehensive understanding of HCWs+OH research.

RT-PCR detection of HIV in Republic of Macedonia

The aim of the study was to detect HIV RNA in seropositive patients using RT-PCR method and thus, to establish PCR methodology in the routine laboratory works. The total of 33 examined persons were divided in two groups: 1) 13 persons seropositive for HIV; and 2) 20 healthy persons - randomly selected blood donors that made the case control group. The subjects age was between 25 and 52 years (average 38,5). ELFA test for combined detection of HIV p24 antigen and anti HIV-1+2 IgG and ELISA test for detection of antibodies against HIV-1 and HIV-2, were performed for each examined person. RNA from the whole blood was extracted using a commercial kit based on salt precipitation. Detection of HIV RNA was performed using RT-PCR kit. Following nested PCR, the product was separated by electrophoresis in 1,5 % agarose gel. The result was scored positive if the band of 210bp was visible regardless of intensity. Measures of precaution were taken during all the steps of the work and HIV infected materials were disposed of accordingly. In the group of blood donors ELFA, ELISA and RT-PCR were negative. Assuming that prevalence of HIV infection is zero, the clinical specificity of RT-PCR is 100 %. The analytical specificity of RT-PCR method was tested against Hepatitis C and B, Human Papiloma Virus, Cytomegalovirus, Herpes Simplex Virus, Rubella Virus, Mycobacterium tuberculosis, Chlamydia trachomatis. None of these templates yielded amplicon. In the group of 13 seropositive persons, 33 samples were analyzed. HIV RNA was detected in 15 samples. ELISA and ELFA test were positive in all samples. Different aliquots of the samples were tested independently and showed the same results. After different periods of storing the RNA samples at -70 masculineC, RT-PCR reaction was identical to the one performed initially. The obtained amplicons were maintained frozen at -20 masculineC for a week and the subsequently performed electrophoresis was identical to the previous one. The reaction is fast, simple for manipulation; with low detection level of 60 IU/ml. RT-PCR needs a small amount of RNA, as well as a small volume of sample. HIV RNA was detected in different periods of time with different clinical presentations in patients, with or without antiretroviral therapy. RT-PCR method gives the opportunity for reliable determination of HIV-1 RNA with border of detection of 60 IU/ml. The test is reproducible and has high analytical and clinical specificity.

Identification of hepatitis B virus core mutants by PCR-RFLP in chronic hepatitis B patients from Punjab, Pakistan

Chronic hepatitis B virus (HBV) infection remains a major health issue worldwide. Several factors including core gene variation are responsible for the development of chronicity of HBV infection. The present study was designed to identify the variations in the core region of the HBV genome in a local population of chronic hepatitis B patients (n = 57) using a PCR-based restriction fragment length polymorphism (PCR-RFLP) method. Fifty subjects were found to be positive for the presence of HBV DNA. For the core region genotyping, the Ava II and Msp I restriction enzymes were used. Mutations at nucleotide (nt) 2147 and nt 2362 in the HBV genome in the core region for Ava II (A4 type, 74%) and nt 2331 for Msp I (M1 type, 66%) were observed as the most common pattern. These results are different from those of previously reported studies on other populations and thus appear to be unique to the Pakistani population. This type of characterization of core mutants may be useful for the design of vaccines based on viral epitopes that are effective for the Pakistani population. Moreover, these unique genotypic patterns for the HBV core gene might be some of the main factors responsible for understanding the underlying mechanism by which HBV chronicity is developed in the Pakistani population.

Hospital transmission of hepatitis B virus in the absence of exposure prone procedures

In February and in June 1998, two people developed acute hepatitis B following in-patient care in a district general hospital. Initial enquiries indicated their infections were not attributable to staff undertaking exposure-prone procedures (EPPs). We report the findings and implications of the subsequent investigation: a multi-disciplinary, multi-agency investigation, including molecular epidemiological analysis. Occupational Health records showed that staff involved in EPPs with the patients were HBsAg negative. No contact between the patients was identified nor were there failures in sterilization. The patients' HBV strains were identical, indicating a common source. A total of 231 out of 232 staff who might have treated either patient were tested for HBsAg; the remaining doctor, working abroad, was HBsAg- and HBeAg-positive and had the same HBV strain as the patients. On two occasions the doctor's hand had been cut while breaking glass vials, but there was no documentation linking these events to the two patients. The doctor had been vaccinated in 1993 and tested for anti-HBs prior to commencing work in 1997. The doctor was recalled to Occupational Health but did not attend and was not followed up. In total, 4948 patients potentially treated by the doctor received an explanatory letter and 3150 were tested for HBsAg. Only one was positive, and HBV sequencing showed no link to the doctor. Occasionally transmission of HBV from heath-care workers can occur in a non-EPP setting and the implications of this require examination by those setting national policy. Occupational Health Services should investigate clinical heath-care workers who do not respond to vaccination. They should ensure HBV carriers are identified and offer them appropriate advice to prevent transmission to patients.

The role of molecular biology and nucleic Acid technology in the study of human infection and epidemiology

OBJECTIVE

In this review, we will focus on recent molecular typing methods that can be applied to different pathogens and assess their values and limitations.

BACKGROUND

Resistant subgroups within a species of pathogenic organisms often emerge as dominant strains under the selective pressures of antibiotics, vaccinations, and new health care practices. The emergence of resistant organisms has added to the burden and cost of health care-related infections. Pathogens derived from a common ancestry are often difficult to distinguish by conventional methods, and the practice of clinical microbiology and infectious disease epidemiology must adapt to this problem.

DISCUSSION

Conventional strain typing methods provide a limited means of distinguishing epidemic from endemic or sporadic isolates of pathogens. Nucleic acid-based methods complement conventional and serologic methods of organism isolation and typing. Often, these genomic methods offer more discrimination and details than the phenotype-based conventional methods.

RESULTS AND CONCLUSIONS

Highly sensitive molecular techniques are capable of detecting single base pair substitutions and resolving the mechanism of underlying complex variation.

Flow cytometry: an 'old' tool for novel applications in medical genetics

Flow cytometry was originally established as an automated method for measuring optical or fluorescence characteristics of cells or particles in suspension. In the meantime, flow cytometers have become user-friendlier, less expensive instruments with an increasing importance in clinical diagnostics. Besides the classical fields of application, such as immunophenotyping blood cells or analyzing the cell cycle status by measuring the DNA content, novel flow cytometric methods have been developed to identify and to quantify disease-related gene sequences. Here we give an overview of current and future applications, including the detection of viral sequences via microsphere-based PCR assays and the analysis of single nucleotide polymorphisms, reflecting individual phenotypic traits. Furthermore, flow cytometry allows the quantification of gene expression changes as well as the isolation of differentially expressed gene sequences. Flow cytometry is also convenient for multiplex analyses, e.g. when hybridizing DNA samples to a mixture of various microsphere populations each coated with different DNA probes. Last but not least, the use of magnetic beads in combination with flow cytometers coupled with automated devices enables molecular diagnostics on a large scale. Overall, this review demonstrates flow cytometry as a rapid, sensitive, and reproducible tool applicable to a wide range of medical genetic approaches.

Efficacy of consensus interferon in the treatment of chronic hepatitis C

BACKGROUND AND AIMS

Consensus interferon (CIFN) is a newly developed type I interferon. The aim of this study was to investigate the safety and efficacy of CIFN in the treatment of patients with chronic hepatitis C and to determine the predictors for sustained response.

METHODS

Patients were randomized to receive 3 micrograms or 9 micrograms CIFN three times a week for 24 weeks, followed by 24 weeks of observation. Efficacy was assessed by normalization of serum transaminase levels and disappearance of serum hepatitis C virus (HCV)-RNA at the end of treatment and at 24 weeks after stopping treatment. Histologic response was defined as a decrease of at least two points in the Knodell necroinflammatory score at week 48 and was compared with baseline.

RESULTS

There were no serious adverse effects related to CIFN therapy. Overall, 44% of patients receiving 3 micrograms and 48% of patients receiving 9 micrograms had normalization of serum transaminase levels and disappearance of HCV viremia at the end of treatment. At 24 weeks after stopping treatment, 16% of patients in receiving 9 micrograms and 12% of patients receiving 3 micrograms had sustained responses. The histologic responses in patients receiving 9 micrograms and those receiving 3 micrograms were 60% and 36%, respectively. The necroinflammatory score was significantly reduced from baseline to week 48 in both groups. In addition, bodyweight < 60 kg and pretreatment serum HCV-RNA level < 0.5 MEq/mL can serve as predictors for sustained response to CIFN treatment.

CONCLUSIONS

These findings suggest that 9 micrograms CIFN is safe and effective in the treatment of patients with chronic hepatitis C.

Transmission of hepatitis C virus in Asia: past and present perspectives

Hepatitis C virus (HCV) infection is a major public health problem. The epidemiology of HCV infection in different parts of Asia is similar, with an average seroprevalence of hepatitis C antibody (anti-HCV) less than 2.5% in healthy adults. The infection is rarely seen in children. The major routes of HCV transmission in Asia during the past few decades have been through administration of therapeutic blood products and injecting drug use, similar to the pattern observed in other parts of the world. However, obvious parenteral routes of transmission only account for 30-60% of anti-HCV-positive cases, depending on the geographic area. Other inapparent parenteral or per-mucosal exposures, including medical intervention, tattooing, acupuncture, vertical and sexual transmission, accidental needlestick and household contact, are also possible routes of HCV transmission. Although screening of blood donors for anti-HCV and improvements in infection control have significantly decreased the exposure to HCV, it is believed that HCV is still spreading in some areas of Asia because of the lack of routine screening of donated blood, injecting drug usage, traditional medicine practices or medical treatment under suboptimal hygienic conditions that involve blood contamination, and tattooing. Accordingly, until effective and safe immunoprophylaxis is available, interruption of transmission routes, such as implementation of blood donor screening for anti-HCV, adequate sterilization of surgical instruments or the use of disposable medical instruments, especially needles and syringes, and avoidance of sharing personal grooming aids remains the mainstay to prevent HCV infection in Asia today.