Download blood-borne pathogens and infection control

BLOOD-BORNE PATHOGENS, TUBERCULOSIS, AND INFECTION CONTROL
September 11, 2012
Timothy R. Cassity, Ph. D., Microbiologist
Southern Ohio Medical Center
1805 27th Street, Portsmouth, OH 45662
Human Immunodeficiency Virus (HIV)
HIV history and prevalence

AIDS was first identified in the United States in 1981 after a number of homosexual men
were diagnosed with Kaposi’s sarcoma.

Although HIV was first identified in 1983, studies of previously stored blood samples indicate
that the virus entered the U.S. population sometime in the late 1970s.

CDC estimates that about 1 million people in the United States are living with HIV or AIDS,
but 21% of these people do not know that they are infected.

In the U. S., 56,000 new infections per year, 16,000 deaths per year (net 44,000 cases/yr)

HIV patients on HAART are expected to live an additional 35 years.

Lifetime treatment cost of $400,000 per patient.
HIV Pathogenesis

HIV causes AIDS by directly inducing the death of CD4+ T cells or interfering with their
normal function.

The median time from infection with HIV to the development of AIDS-related symptoms has
been approximately 10 years in the absence of antiretroviral therapy.

Numerous studies show that people with high levels of HIV in their bloodstream are more
likely to develop AIDS-related symptoms or die than those with lower levels of virus.
HIV transmission

HIV is a fragile virus. It cannot live for very long outside the body.

HIV cannot be transmitted by shaking hands, hugging, casual kissing, toilet seats,
doorknobs, drinking fountains, dishes, glasses, food, pets, mosquitoes, saliva, tears,
sweat, or by being scratched.

Feces, nasal secretions, saliva, sputum, sweat, tears, urine, and vomitus are not
considered potentially infectious unless they are visibly bloody

HIV is primarily found in the blood, semen, or vaginal fluid of an infected person. Blood is
the primary concern. Cerebrospinal fluid, synovial fluid, pleural fluid, peritoneal fluid,
pericardial fluid, and amniotic fluid are also considered potentially infectious.

HIV is transmitted in 3 main ways:
o Having sex (anal, vaginal, or oral) with someone infected with HIV
o Sharing needles and syringes (or a needle stick) with someone infected with HIV,
o Being exposed (fetus or infant) to HIV before or during birth or through breast
feeding
Bloodborne pathogens – September 11, 2012
Page 1 of 7

The average risk for HIV transmission after a percutaneous exposure to HIV-infected
blood has been estimated to be approximately 0.3%.

The average risk for HIV transmission after a mucous membrane exposure is
approximately 0.09%.

Increased risk for HIV infection was associated with exposure to a larger quantity of blood
from the source person. The risk also was increased for exposure to blood from source
persons with terminal illness, possibly reflecting either the higher titer of HIV in blood late
in the course of AIDS.
HIV diagnosis

You cannot rely on symptoms alone because many people who are infected with HIV do
not have symptoms for many years. The only way to know whether you are infected is to
be tested for HIV.

A new testing algorithm is supposed to be published by CDC later this year. It will use
both antigen and antibody testing. This will detect infected patients earlier than antibody
alone. If the antigen or antibody screen is positive, a rapid confirmatory test capable of
distinguishing between HIV 1 and HIV 2 should be performed. The Western blot can still
be done, but takes longer and is more expensive.

Oral swabs are still acceptable for screening for HIV 1 and HIV 2.

HIV nucleic acid (RNA) detection is a Reverse transcriptase DNA polymerase chain
reaction [RT-PCR] can be used to evaluate patients that are positive with the screen but
negative by the confirmatory test. It can still be used to monitor HIV load in a known
positive patient. It is useful for determining treatment regimen and clinical course.

HIV screening should be performed on all pregnant women.

Separate written consent for HIV testing is no longer required; general consent for
medical care is considered sufficient to encompass consent for HIV testing. Patients can
still decline HIV testing. A patient’s declination should be noted in their medical record.
HIV prevention

HIV Prevention: Abstinence, fewer sexual partners, condoms, not sharing needles.

Antiretroviral drugs lessen the likelihood of transmission

Instruments that are intended to penetrate the skin should be used only once and
disposed of or thoroughly cleaned and sterilized.

Instruments not intended to penetrate the skin but which may become contaminated with
blood should be used for only one client and disposed of or thoroughly cleaned and
disinfected after each use.
HIV vaccine – non in the foreseeable future
Post-exposure testing and prophylaxis(PEP)

PEP is effective of preventing HIV infections in some circumstances.

Before initiating PEP test both the source (if available) and the employee.

If source is negative or employee is positive, non PEP is indicated.
Bloodborne pathogens – September 11, 2012
Page 2 of 7

If employee is initially negative, retest at 3 months, if 3 month test is negative, retest at 6
months. If 6 month test is negative, retest after 1 year.

PEP, if indicated, should be initiated as soon as possible, preferably within 4 hours.

For drugs for PEP, contact http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5011a1.htm
Pre-exposure prophylaxis (PrEP)

In a study conducted byCDC in partnership with the Botswana Ministry of Health, a
once-daily tablet containing tenofovir and emtricitabine reduced the risk of acquiring HIV
infection by roughly 63% in the study population of uninfected heterosexual men and
women.
Hepatitis B Virus (HBV)

Originally called serum hepatitis. The first recorded cases hepatitis B are thought to be
those that followed the administration of smallpox vaccine containing human lymph to
shipyard workers in Germany in l883.

Australia antigen, later called hepatitis B surface antigen (HBsAg), was first described in
1965, and the Dane particle (complete hepatitis B virion) was identified in 1970
Prevalence

In 1987, the CDC estimated the total number of HBV infections in the United States to be
300,000 per year.

Of these infected individuals, 18,000-30,000 (6%-10%) will become HBV carriers, at risk
of developing chronic liver disease (chronic active hepatitis, cirrhosis, and primary liver
cancer), and infectious to others.

Before use of the HBV vaccine approximately 12,000 health-care workers became
infected with HBV each year. 700-1,200 of those infected become HBV carriers.
Approximately 250 would die from liver disease.

The annual number of occupational infections has decreased >95% since hepatitis B
vaccine became available in 1982,
Hepatitis B transmission

Hepatitis B is not spread through food or water, sharing eating utensils, breastfeeding,
hugging, kissing, coughing or sneezing, or casual contact.

HBV is spread through having sex with an infected person without using a condom,
sharing needles and drug paraphernalia. needle sticks or sharps exposures on the job,
and perinatally.

Saliva of some persons infected with HBV has been shown to contain HBV-DNA at
concentrations 1/1,000 to 1/10,000 of that found in the infected person's serum, but the
potential for salivary transmission of HBV is remote.

For a susceptible person, the risk from a single needlestick or cut exposure to HBVinfected blood ranges from 6-30%.

HBeAg positive person is higher risk for transmission than a HBeAg negative person
Bloodborne pathogens – September 11, 2012
Page 3 of 7
HBV diagnosis

Frequently a person with HBV infection has no symptoms at all or doesn’t recall any.
Only a blood test can tell for sure. Order HBsAg, anti-HBs, anti-HBc. If chronic HBV is
suspected, order HBeAg and anti-HBe.

HBsAg will be detected in an infected person’s blood on the average of 4 weeks (range
1-9 weeks) after exposure to the virus.
HBV Prevention

HBV prevention includes standard precautions, careful handling of sharps, proper
disposal of infectious waste, and HBV vaccine

Hepatitis B vaccine - DHHS and the Dept of Labor stated that hepatitis B vaccine should
be provided to workers that are at risk at no charge to the worker.

Hepatitis B vaccines have been shown to be safe when administered to both adults and
children. Neither pregnancy nor breastfeeding should be considered a contraindication to
vaccination of women. Recent studies indicate that immunologic memory remains intact
for at least 23 years and confers protection against clinical illness and chronic HBV
infection.
HBV Exposure

Test source, if available, and test employee.

For an exposure to a source positive for HBsAg, the worker who has not previously been
given hepatitis B vaccine should receive the vaccine series, a single dose of hepatitis B
immune globulin (HBIG), if given within 7 days of exposure.

For exposures from an HBsAg-positive source to workers who have previously received
vaccine:

Test for antibody to hepatitis B surface antigen (anti-HBs), if negative give one dose of
vaccine and one dose of HBIG

If the source individual is negative for HBsAg and the worker has not been vaccinated,
this opportunity should be taken to provide hepatitis B vaccination.
Hepatitis C Virus (HCV)
HCV Prevalence

Hepatitis C is the leading cause of liver transplants in the United States.

Hepatitis C infects an estimated 170 million people worldwide and 4 million in the United
States. Up to 85% are unaware they are infected.

Co-infection with HIV is common. Approximately 350,000 of patients in the USA infected
with HIV are also infected with the hepatitis C virus.

There are numerous cases of Hepatitis C in southern Ohio – the highest per capita rate in
Ohio.

Prevalence among persons born between 1945 and 1965 is approximately 3.3%.
Therefore, CDC has recommended that all persons in this age group be screened for
HCV, at least once. Those that are positive should be further evaluated and treated to
prevent hepatocarcinoma.
Bloodborne pathogens – September 11, 2012
Page 4 of 7
HCV Pathogenesis

60% to 70% of people infected develop no symptoms during the acute phase, but
ensuing chronic hepatitis can result later in cirrhosis and liver cancer.

In the patients who experience acute phase symptoms, they are generally mild and
nonspecific, and rarely lead to a specific diagnosis of hepatitis C.

Approximately 20-30% of persons infected with HCV clear the virus from their bodies
during the acute phase.

70-80% of patients infected with HCV develop chronic hepatitis C, (infection lasting more
than 6 months). Among untreated patients, roughly one-third progress to liver cirrhosis in
less than 20 years, another third progress to cirrhosis within 30 years. The remainder
progress so slowly that they are unlikely to develop cirrhosis within their lifetimes.
HCV Diagnosis

The detection of anti-HCV antibodies in plasma or serum is based on the use of enzyme
immunoassays (EIA). Anti-HCV antibodies can be detected in 80% of patients within 15
weeks after exposure, >90% within 5 months after exposure, and >97% by 6 months
after exposure.

The presence of the virus is tested for using molecular nucleic acid testing methods
(PCR, TMA, or branched DNA (b-DNA)

Liver biopsy is the best test to determine the amount of scarring and inflammation.
HCV Transmission

Injection-drug use continues to be the most commonly identified risk factor for infection.
Approximately 1/3 of young IV drug users are infected with HCV.

HCV is spread inefficiently sexually, although it does occur.

HCV is not spread through casual contact, hugging or kissing, sharing eating or cooking
utensils.

HCV is spread by illicit drug use, occupational expose to blood, body piercing and
tattoos, and blood transfusions - rare today because blood supply is tested for HCV.
HCV Prevention

There is no vaccination that protects against contracting Hepatitis C.

Avoid high risk activities and contact with blood from infected individuals. Use proper
safety measures (Standard precautions)
HCV Post-Exposure

Determine status of source of exposure, if negative, no additional testing necessary

If source is positive and employee at baseline is negative, test at 3 months. If employee
was negative at 3 months, test again at 6 months.
Tuberculosis

In 1900 TB was the leading cause of death in the U.S.

Nationwide, from the late 40’s the incidence decreased until 1984. Cases decreased
such that it was thought that TB would be a historic disease by 2005.
Bloodborne pathogens – September 11, 2012
Page 5 of 7

Cases began to increase in 1985, mainly due to HIV and MDR strains.

Locally, we have a low rate of tuberculosis – 1-3 new cases per year.

Two forms of the disease:
o Latent tuberculosis - positive PPD only, no symptoms, cannot spread to others
o Active tuberculosis – symptoms are present – can spread to others if pulmonary.

Can be (and usually is) carried for a long time before onset of active disease.

Transmitted by inhaling infected droplets from a person with active pulmonary
tuberculosis.

With active TB, respiratory isolation and standard precautions are used to prevent spread
of infection.
Tuberculosis and HIV

Because HIV infection weakens the immune system, people infected with HIV and TB
have a 100 times greater risk of developing active TB disease compared to people not
infected with HIV.

TB is the cause of death for one out of every three people with AIDS worldwide.

Individuals that are HIV positive may not test correctly with PPD.
General Infection Control

Most important Aspect - Common Sense
o Use the appropriate barrier, proper hand hygiene, careful handling of sharps

Disinfectants –
o Sodium hypochlorite – a 1:10 dilution of household bleach with 5% sodium
hypochlorite is fine, but must be made fresh daily. Dispatch is stabilized Na
hypochlorite

Gloves
o Not a replacement for handwashing. Use when exposure to blood or a body fluid
is anticipated. Only single-use gloves should be used in patient care.

Sharps - Most sharps injuries are avoidable!
o Most people who are injured with sharps were not the persons using the sharp!
o Place sharps immediately into an impervious sharps container with needle facing
down Do not overfill a sharps container
Employer’s Responsibilities

Employers should make protective equipment available to all workers

Employers should ensure that the appropriate protective equipment is
used by workers

Employers should establish a detailed work practices program that includes
standard operating procedures (SOPs).
Bloodborne pathogens – September 11, 2012
Page 6 of 7

Employers should monitor the workplace to ensure that required work
practices are observed and that protective clothing and equipment are
provided and properly used.

Training records, indicating the dates of training sessions, the content of
those training sessions along with the names of all persons conducting the
training, and the names of all those receiving training should also be
maintained.

All workers whose jobs involve participation in tasks or activities with
exposure to blood or other body fluids to which universal precautions apply
should be offered hepatitis B vaccine.
References:
All of the information in the program can be found at the CDC website: www.cdc.gov
For information relating to what to do if a healthcare worker is exposed to blood, see:
http://www.cdc.gov/ncidod/dhqp/pdf/bbp/Exp_to_Blood.pdf
Bloodborne pathogens – September 11, 2012
Page 7 of 7