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

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

HCV Transmission in the health care setting

Patient to Health Care Workes percutaneous 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

Patient to Health Care Workes

Conflicting results on the risk of HCV transmission

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

Risk of Health Care Workers HCV infection following needlestick/cut from a positive (infected) source:

1.8% (range 0%-7%)

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) 1-2Oral surgeons (1992) 2General surgeons (1991-1992) 1Orthopedic surgeons (1991) 1General dentists (1992) 1Emergency response (1991-2000) 1-3General population of adults 1.8

Factors Influencing OccupationalRisk of HCV Infection

Prevalence of infection among patients

Immune status of the worker and specific immune response of the infected individual

The type/route of exposure

The amount of virus in the infected blood at the time of exposure

The amount of infected blood involved in the exposure

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)

Whether post-exposure treatment was taken

Health Care Workes to Patient

Orthopaedic Surgery (Ross 2002)Cardiothoracic Surgery (Esteban1996)Gynaecology (PHLS 1999, Ross 2002)Anaesthesiology (Ross 2000)

Transmission mechanism:Percutaneous injury

Injection material shared with patients

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

Nosocomial infection

Infection acquired in the hospital

due to exposure to the pathogen

in the hospital

Problematic aspects

of the HCV Transmission in Healthcare Settings

Risk factors for Healthcare Settings transmission not well definedHowever, HCV environmental transmission is a proven and documented fact, although HCV rapidly degrades at room temperatureAlthough 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.

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

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 understood problem of environmental virology today.

Health care setting - a very broad term and wide range of….

Equipment

Devices

Surfaces

Medical procedures

Bedding

Clothes

Medical personnel

Patients

Etc........

Two main types of envinronmental samples from health care setting

Swabs Extracts

Equipment Devices

Surfaces

Etc........

Clothes

Bedding

Bandages, cotton wool

Etc........

Sample preparationSwabs processing:

1. Specific extracting buffers should be used to moisten swabs.

2. Moistened swabs should be employed for all sampling of surfaces.

3. Wherever possible the size of the area sampled should be greater than 100cm2

Extraction:

1. Place blood-contaminated fragments of bedding, clothes etc. into a sterile flask with appropriate volume (1: 5 w/v) of extracting solution

2. Shake the flask for 20-40 min, press out.

3. Transfer the liquid phase into a new flask.

Detection of HCV-positive environmental extracts

Obtaining of environmental extracts

Ultracentrifugation

Elution of viral particles from adsorbent

Viral particle adsorption on powder or fiber adsorbents

Eluate

PEG-precipitaion

HCV Detection in PCR

Highly effective virus adsorbent: Highly effective virus adsorbent:

mineral fiber “Fiban”mineral fiber “Fiban”

1818

0 20 40 60 80 100

10

20

30

10

20

30

10

20

30

Adsorbtion efficacy, %

Ads

orbe

nt q

uant

ity,

g

А7

А6

АК22-Э

АК22-В

А5

Material Name

Characteristics

Functional group

Ion typesIon-

exchange behaviour

A-5 fiban

–N=, =NH, –COOH

CompositeCl-, HSO4

-, HCO3

-,

Anionite

A-6 fiban

–N=, –N≡ Carbonate(CO3

2-, HCO3-)

Anionite

AK-22 fiban

–NH2, =NH, –COOH

CompositeCl-, HSO4

-, HCO3

-,

Anionite

Our experimental data showed almost 100% efficacy of enterovirus adsorbtion-elution from water with anion-exchanged mineral fiber “Fiban”

Detection of HCV-positive environmental swabs

Obtaining of environmental swabs with extracting buffer solutions

Ultracentrifugation PEG-precipitaion

HCV Detection in PCR

or

2. Detection algorithm to confirm a link between environmental HCV

contamination and nosocomial infectionDetection of hemoglobin-contaminated environmental samples

Detection of HCV-positive environmental samples

Amplification and sequencing of a part of HCV genome

Phylogenetic reconstruction

Molecular-epidemiology analysis

Detection of HCV-positive samples from patients

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

Role of Environmental Contamination in the Risk of Hepatitis C Virus Transmissionin a Hemodialysis Unit

E. 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) 1sequences from patients known to be infected with HCV and regularly treated in hemodialysis unit and the 5 environment surfaces that tested positive for HCV RNA

ConclusionThere are many issues connected with various aspects of health care 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.

Republican Research and Practical Center for Epidemiology and

Microbiology, Minsk, Belarus

Laboratory of environment virology

amvrosieva@gmail.com

THANK YOU FOR THANK YOU FOR YOUR YOUR ATTENTIONATTENTION