Blood borne pathogens

DR RITESH SHIWAKOTI

MScD PROSTHODONTICS

• Bloodborne pathogens are infectious microorganisms present in blood that can cause disease in humans. These pathogens include, but are not limited to, hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV), the virus that causes AIDS.

• Bloodborne infections are those where the blood contains infectious agents that can be transferred into the body of another person giving rise to infection (Advisory Committee on Dangerous Pathogens)

Factors involved in the risk of transmission include:

• The length of time that the infectious agent remains in the blood

• The amount of agent that is present

• Its virulence (i.e. its ability to cause disease) and

• The susceptibility of the recipient

OPIM “Other Potentially InfectiousMaterials” means:

1. Semen2. Vaginal secretions3. Cerebrospinal fluid4. Synovial fluid5. Pleural fluid6. Pericardial fluid7. Peritoneal fluid 8. Amniotic fluid9. Saliva in dental procedureany other body fluid that is visibly contaminated with blood

such as saliva or vomitus, and all body fluids, such as emergency response.

2. Any unfixed tissue or organ (other then intact skin) from a human (living or dead)

3. HIV – Containing cell or tissue culturesOrgan culture, and HIV- or HBV- containing culture medium or

other solutions: blood, organs, or other tissues from experimental animals infected with HIV or HBV, needle sticks, human bites, cuts, and abrasions.

Other body fluid

Excreta and secretions i.e. urine, faeces, sputum, tears, sweat and vomit are considered to present little risk from bloodborne infection unless they contain visible blood. However, they may pose a risk of infection for other reasons

Routes of transmission

Percutaneous exposure through:

Major routes

• Sharing injecting equipment

• Skin puncture by contaminated sharp objects such as needles, instruments or glass

• Transfusion of infected blood products

Less common routes

• Contamination of open wounds and skin lesions

• Human bite (transmission of HBV and HIV have been documented but not quantified)

Mucocutaneous exposure through:

Major routes

• sexual intercourse

• childbirth and/or breastfeeding in infected mothers

Less common routes

• Contamination of mucous membranes of the eye, nose or mouth (transmission of HBV and HIV following exposure of mucous membranes)

Risks to health workers

Risk of occupational transmission occurs whenever there is exposure to blood or body fluids.

• Health workers who are regularly involved in invasive procedures, i.e. any use of needles, or instruments in penetrating the body, or otherwise in contact with blood or body fluid.

• Sharps injury is by far the most commonly reported exposure amongst health workers

Examples include

• Surgery• Obstetrics and gynaecology• Dentistry• Accident and emergency work• Post-mortem• Venepuncture and phlebotomy. Ancillary and other staff may also be put at risk

through careless disposal of sharps, linen and clinical waste.

Transmission to patients during invasive procedures

• Doctors were reported as not always washing their hands or changing gloves (if worn) between cannulainsertions

• It was not usual practice for staff to wash their hands or change gloves between volunteers when taking blood samples

• Kidney dishes used to transport samples and equipment were not decontaminated or discarded between volunteers

• Equipment contaminated with blood was sometimes left on bedside lockers.

Control measures

• Universal precaution

• wash hands before and after every patient contact, and immediately after direct contact with blood or body fluids, avoid hand to mouth/eye contact

• wear gloves when contact with blood or body fluids, mucous membranes or non-intact skin is anticipated, and wash hands after their removal

• Prevent puncture wounds, cuts and abrasions in the presence of blood and body fluids

• Protect skin lesions and existing wounds by means of waterproof dressings and/or gloves

• Avoid use of, or exposure to, sharps and sharp objects when possible, but where unavoidable take particular care in their handling and disposal

• Avoid contamination of the person by use of waterproof or water-resistant clothing, plastic apron, etc.

• Wear rubber boots or plastic disposable overshoes to protect shoes; when the floor is contaminated with blood, wash hands after removing footwear

• Control surface contamination by blood and body fluids by containment and appropriate decontamination procedures

Management of exposure to blood or body fluids

• Wash off splashes on skin with plenty of soap and water; • If the skin has been punctured or broken, encourage bleeding but

without pressing or sucking the wound • Splashes to the eye, nose, or mouth should be washed out with

copious amounts of water (sterile water for the eye if available); • Record the source of contamination, i.e. name of source (if known),

type of fluid, type of injury, and how it occurred; • Report the injury to the supervisor, line manager or other person

responsible for health and safety at work, as in local policy; • Medical advice should be sought from the occupational health

department or other medical adviser without delay, in accordance with local policy.

Further action

The local plan for management of exposure should consider: • The source of contamination and the extent of

injury/exposure; • Blood sampling and/or serum sample storage; • Vaccination status; • Provision of immediate and follow-up counselling and

support; • The need for post-exposure prophylaxis; • Completion of accident forms; • Surveillance of incidents; • Review of procedures.

Human immunodeficiency virus (HIV)

• Worldwide, the majority of HIV infections are caused by human immunodeficiency virus type 1 (HIV 1).

• A second virus, HIV 2, is found mainly in West Africa but has been detected in individuals in other areas of sub-Saharan Africa, the USA, India and Europe.

• A further virus, a sub-type of HIV 1, has recently been recognized and is referred to as HIV 0.

Epidemiology

• HIV/AIDS is a global pandemic. As of 2011 approximately 34 million people have HIV worldwide .Of these, approximately 17.2 million are men, 16.8 million are women and 3.4 million are less than 15 years old.There were about 1.8 million deaths from AIDS in 2010, down from 2.2 million in 2005.

• Sub-Saharan Africa is the region most affected

• South & South East Asia (a region with about 2 billion people as of 2010, over 30% of the global population) has an estimated 4 million cases (12% of all people living with HIV), with about 250,000 deaths in 2010. Approximately 2.5 million of these cases are in India

• Since AIDS was first recognized in 1981 and by 2009 has led to nearly 30 million deaths.

• Officially, the Philippines is a low-HIV-prevalence country, with less than 0.1 percent of the adult population estimated to be HIV-positive. As of January 2013, the Department of Health (DOH) AIDS Registry in the Philippines reported 10,514 people living with HIV/AIDS.

PATH-PHYSIOLOGY

• HIV is a retrovirus.

• Retroviruses contain two strands of RNA and are able to transcribe their RNA into a DNA by means of an enzyme, reverse transcriptase.

• The HIV virus binds, with a specific cellular receptor CD4 antigen, present on the surface of certain cells.

• These CD4 receptor cells include helper T-lymphocytes, mononuclear phagocytes, macrophages and glial cells in the brain.

• After binding to a cell the HIV virus enters and forms a DNA copy through reverse transcription.

• This copy is then integrated into the host cell DNA, where it remains in a relatively inactive state.

• Over time cell damage occurs, and there is a continuing reduction in the numbers of circulating helper T-cells and other CD4 cells

• Resulting in an increasingly compromised immune response and, in some individuals, progressive brain damage.

Transmission:

• Sexual contact with infected person

• Needle-sharing during intravenous drug use

• Needle stick injury

• Transfusion of contaminated blood or blood product

• Medical injections with unsterilized equipment.

• From mother to child during pregnancy, during delivery, or through breast milk

Symptoms

Primary Infection, or Acute Retroviral Syndrome• Fever,• Myalgia (muscle pain),• Headache,• Nausea, vomiting, diarrhea,• Night sweats,• Weight loss,and• Rash.These signs and symptoms usually occur 2–4 weeks after

infection, subside after a few days, and often are misdiagnosed as influenza or infectious mononucleosis.

Clinical Latency/Asymptomatic Disease

(Clinical Stage 1)

Period of years between HIV infection and clinical signs and symptoms of AIDS.

This is when the “viral set point” is established. The viral load of the set point can be used to predict how quickly disease progression will occur and this phase may last 8–10 years

Mild Signs and Symptoms of HIV (Clinical Stage 2)

• Candidiasis,

• Lymphadenopathy,

• Molluscom contagiosum,

• Persistent hepatosplenomegaly,

• Popular pruritic eruptions,

• Herpes zoster, and/or

• Peripheral neuropathy

Advanced Signs and Symptoms of HIV

(Clinical Stage 3)

• Cryptosporidiosis ( parasitic infection )

• Pulmonary and lymph node tuberculosis,

• Wasting

• Persistent fever (longer than one month)

• Persistent candidiasis

• Recurrent bacterial pneumonia and

• Other opportunistic infections is common.

Clinical Stage 4

Investigation

• Enzyme-linked immunosorbent assay

• DNA PCR and RNA PCR

• Western blot analysis

• Immunofluorescence assay

Prevention

• Condom

• A vaginal gel containing tenofovir

• Post-exposure prophylaxis (PEP) A course of antiretrovirals administered within 48 to 72 hours after exposure for 4 week e.g. zidovudine , lamivudine , indinavir

• 2013, the prevention regimen recommended in the United States consists of three medications—tenofovir, emtricitabine and raltegravir

Vaccination

As of 2012 , single trial of the vaccine RV 144 published in 2009 found a partial reduction in the risk of transmission of roughly 30%, stimulating some hope , further trials of the RV 144 vaccine are ongoing.

Antiviral therapy

Most current HAART regimens consist of three(3) drugs: 2 NRTIs + a PI/NNRTI

Examples of NRTIs include deoxythymidine, zidovudine, stavudine, didanosine, zalcitabine, abacavir, lamivudine, emtricitabine, and tenofovir

NNRTIs, include nevirapine, delavirdine, efavirenz, and rilpivirine

HIV protease inhibitors Lopinavir,Indinavir, Nelfinavir, Amprenavir and Ritonavir

Prognosis

• Over time continuing CD4 cell depletion leads to increasing immunosuppression, opportunistic infections and eventual death for the majority

Hepatitis B virus

• It is a double-stranded DNA hepadnavirus and the whole virus is called the Dane particle.

• The hepatitis B virus is a major cause of acute and chronic hepatitis, cirrhosis and hepatocellular carcinoma worldwide.

Epidemiology

• In 2004, an estimated 350 million individuals were infected worldwide. National and regional prevalence ranges from over 10% in Asia to under 0.5% in the United States and northern Europe

• Philippines has 16 million people infected with Hepatitis B virus (HBV)

Transmission

• Sexual contact

• Blood transfusions and transfusion with other human blood products

• Re-use of contaminated needles and syringes, and

• Vertical transmission from mother to child (MTCT) during childbirth

Signs and symptoms

Acute viral hepatitis – an illness that begins• General ill-health• Loss of appetite• Nausea• Itchy skin• Vomiting• Body aches• Mild fever• Dark urine• Jaundice

Chronic infection with hepatitis B virus either may be asymptomatic or may be associated with a chronic inflammation of the liver (chronic hepatitis), leading to cirrhosis and incidence of hepatocellular carcinoma (liver cancer)

• Symptoms outside of the liver are present in 1–10% of HBV-infected people and include serum-sickness–like syndrome, acute necrotizing vasculitis(polyarteritis nodosa), membranous glomerulonephritis

Investigation

• Enzyme-linked immunosorbent assay

• DNA PCR and RNA PCR

• Western blot analysis

• Immunofluorescence assay

Prevention

Hepatitis B vaccine:

- A course of 3 vaccine injections are given with the 2nd injection at least 1 month after the 1st

dose and the 3rd injection given six months after the 1st dose.

Newborn (with carrier mothers):

- hepatitis B vaccine (HBV 1) and hepatitis B immune globulin (HBIG) within 12 hours of birth, followed by a second dose of hepatitis B vaccine (HBV 2) at 1–2 months and a third dose at and no earlier than 6 months (24 weeks)

• For carrier mothers: multiple injections of small doses of hepatitis B immune globulin or oral lamivudine in HBV carrier mothers with a high degree of infectiousness in last trimester

• Poor responses are mostly associated with being over the age of 40 years, obesity and smoking,and alcoholics, advanced liver disease. Patients on renal dialysis may respond less well and require larger or more frequent doses of vaccine.

• As of 2008, there are seven medications licensed for treatment of hepatitis B infection in the United States.

• Include antiviral lamivudine, adefovir , tenofovir , telbivudine and entecavir , and the two immune system modulators interferon alpha-2a and PEGylatedinterferon alpha-2a (Pegasys).

• The use of interferon, which requires injections daily or thrice weekly, has been supplanted by long-acting PEGylated interferon which is injected only once weekly

Hepatitis C

• HCV is a positive stranded RNA virus • Hepatitis C is an infectious disease affecting

primarily the liver.• The infection is often asymptomatic, but chronic

infection can lead to scarring of the liver and ultimately to cirrhosis.

• In some cases, those with cirrhosis will go on to develop liver failure, liver cancer or life-threatening esophageal and gastric varices.

• HCV is spread primarily by blood-to-blood contact associated with intravenous drug use, poorly sterilized medical equipment and transfusions.

Epidemiology

It is estimated that 150–200 million people, or 3% of the world's population, are living with chronic hepatitis C. About 3–4 million people are infected per year, and more than 350,000 people die yearly from hepatitis C-related diseases.

• The incubation period is in the range of 1 to 26 weeks and only about 5% of acute HCV infection is associated with signs and symptoms of acute hepatitis.

Signs and symptoms

Acute infection:

• decreased appetite

• fatigue

• nausea

• muscle or joint pains,

• weight loss and

• rarely acute liver failure

• jaundice

Chronic infection:Fatigue and mild cognitive problemsFatty liverCirrhosisHepatocellular carcinomaAscitesEasy bruising or bleedingvarices (enlarged veins)Hpatic encephalopathy

Investigation

• HCV antibody enzyme immunoassay or ELISA, recombinant immunoblot assay, and quantitative HCV RNA polymerase chain reaction(PCR)

Treatment

As of 2010, treatments consist of a combination of pegylated interferon alpha and the antiviral drug ribavirin for a period of 24 or 48 weeks

Hepatitis C is a common reason for liver transplantion