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HCV infection in health care workers and methodic approaches to identify HCV contamination

HCV infection in health care workers and methodic approaches to identify HCV contamination. Tamara Amvrosieva , Natallia Paklonskaya, Olga Kazinethz Republican Research and Practical Center for Epidemiology and Microbiology, Minsk, Belarus.

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HCV infection in health care workers and methodic approaches to identify HCV contamination

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  1. HCV infection in health care workers and methodic approaches to identify HCV contamination Tamara Amvrosieva, Natallia Paklonskaya, Olga Kazinethz Republican Research and Practical Center for Epidemiology and Microbiology, Minsk, Belarus

  2. Potential Modes of HCV Transmission in Health Care Settings Direct contact with blood Needle stick or sharps injury Splash to eye Non-intact skin Blood transfusion/organ transplant Indirect contact with blood Hemodialysis HCW hands Re-used equipment (e.g., glucose monitoring, syringes, needles) Injectable medication, infusion, flush solution

  3. HCV Transmission in the health care setting Patient to Health Care Workespercutaneous exposure to infected patients’ blood: multiple case reports - splashes of blood onto health care workers’ (HCW) mucous membranes: few case reports Health Care Workes to Patient Patient to patient

  4. Patient to Health Care Workes Conflicting results on the risk of HCV transmission

  5. Risk of Health Care Workers HCV infection following needlestick/cut from a positive (infected) source: 1.8% (range 0%-7%) The number of health care  workers who have acquired HCV occupationally is not known. However, of the total acute HCV infections that have occurred annually 1% to 10% have been in health care workers exposed to blood in the workplace

  6. Frequency of Percutaneous Injury in Health care Personnel Frequency of percutaneous injury varies by occupational group and healthcare setting Prevalence of HCV Infection in health care workers United States Group% Infection Hospital-based (pre-1980) 1-2 Oral surgeons (1992) 2 General surgeons (1991-1992) 1 Orthopedic surgeons (1991) 1 General dentists (1992) 1 Emergency response (1991-2000) 1-3 General population of adults 1.8

  7. Factors Influencing OccupationalRisk of HCV Infection Prevalence of infection among patients Immunestatusoftheworker and specificimmuneresponseoftheinfectedindividual Thetype/routeofexposure Theamountofvirusintheinfectedbloodatthetimeofexposure Theamountofinfectedbloodinvolvedintheexposure Nature and frequency of blood exposures (for example splash to mucous membranes, cut, needlestick, skin contamination, quantity of blood involved and concentration of HCV in the blood) Whetherpost-exposuretreatmentwastaken

  8. Health Care Workes to Patient • Orthopaedic Surgery (Ross 2002) • CardiothoracicSurgery (Esteban1996) • Gynaecology (PHLS 1999, Ross 2002) • Anaesthesiology (Ross 2000) • Transmissionmechanism: • Percutaneousinjury • Injection material shared with patients

  9. HCV transmission: HCWs to patient(Gunson et al. J. Clin. Virol. 2003)

  10. Nosocomial infection Infection acquired in the hospital due to exposure to the pathogen in the hospital

  11. Problematic aspects of theHCV Transmission in Healthcare Settings Risk factors for Healthcare Settings transmission not well defined However, HCVenvironmental transmission is a proven and documented fact, although HCV rapidly degrades at room temperature Although some factors (e.g. virus titer) might be related to transmission of HCV,no methods exist currently that can reliably determine infectivity, nor do data exist to determine threshold concentration of virus required for transmission.

  12. The investigetion includes two stages: 1. Detection and identification of environmental HCV contamination (Laboratory Environmental Control) 2. Establishment of a connection between HCV contamination of health care setting and nosocomial transmission. Determine whether transmission took place

  13. 1. Lanoratory Environmental Control Main objective:envinronmental and virological investigations of health care settings to catch HCV particles and concentrate them in a small volume • The development of effective methods to identify HCV contamination in health care settings(equipment, surfaces, clothing, bedding, body of medical personnel, etc.) is an actual and poorly understoodproblem of environmental virology today.

  14. Health care setting - a very broad term and widerange of…. Equipment Devices Surfaces Medical procedures Bedding Clothes Medical personnel Patients Etc........

  15. Two main types of envinronmental samples from health care setting Swabs Extracts • Equipment • Devices • Surfaces • Etc........ • Clothes • Bedding • Bandages, cotton wool • Etc........

  16. Sample preparation Swabs processing: Specific extracting buffersshould be used to moisten swabs. Moistened swabs should be employed for all sampling of surfaces. Wherever possible the size of the area sampled should be greater than 100cm2 • Extraction: • Place blood-contaminated fragments of bedding, clothesetc. into a sterile flask with appropriate volume (1: 5 w/v) of extracting solution • Shake the flask for 20-40 min, press out. • Transfer the liquid phase into a new flask.

  17. Detection of HCV-positive environmental extracts Obtaining of environmental extracts Viral particle adsorption on powder or fiber adsorbents Elution of viral particles from adsorbent Eluate Ultracentrifugation PEG-precipitaion HCV Detection in PCR

  18. Highly effective virus adsorbent: mineral fiber “Fiban” Our experimental data showed almost 100% efficacy of enterovirusadsorbtion-elution from water with anion-exchanged mineral fiber “Fiban”

  19. Detection of HCV-positive environmental swabs Obtaining of environmental swabs with extracting buffer solutions Ultracentrifugation PEG-precipitaion or HCV Detection in PCR

  20. 2. Detection algorithm to confirm a link between environmental HCV contamination and nosocomial infection Detection of hemoglobin-contaminated environmental samples Detection of HCV-positive environmental samples Detection of HCV-positive samples from patients Amplification and sequencing of a part of HCV genome Phylogenetic reconstruction Molecular-epidemiology analysis

  21. Close phylogenetic relationship between RNA sequences from environmental samples and those isolated from patient or health care workers points out at nosocomial HCV transmission. Assessment of the results

  22. Role of Environmental Contaminationin the Risk of Hepatitis C Virus Transmissionin a Hemodialysis UnitE. Girou, et al. //Clinical Infectious Diseases 2008; 47:627–33 Blood-contaminated surfaces may be a source of HCV cross-transmission in a hemodialysis unit. Figure.Phylogenetic tree plotted with hypervariable region (HVR) 1 sequences from patients known to be infected withHCV and regularly treated in hemodialysis unit and the 5 environment surfaces that tested positive for HCV RNA

  23. Conclusion There are many issues connected with various aspects of healthcare setting related HCV infections: Long incubation period of HCV makes revealing of environmental source of infection extremely difficult or even impossible Specific approaches to detection of environmental HCV contamination are not developed no methods currently exist that can reliably determine infectivity and threshold concentration of virus required for transmission Requires further investigation to develop methods for risk assessment of nosocomial infection based on evidence of infectious properties of HCV.

  24. THANK YOU FOR YOUR ATTENTION Republican Research and Practical Center for Epidemiology and Microbiology, Minsk, Belarus Laboratory of environment virology amvrosieva@gmail.com

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