| Introduction |
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The human immunodeficiency virus (HIV) is transmitted
from person to person via the following routes:
- Sexual contact during which body fluids are exchanged.
- Transfusion of infected blood and blood products.
- Perinatal transmission from mother to child.
- Contact with infected needles and body fluids.
This write-up discusses the risks of acquiring HIV
infection faced by medical personnel when caring for
HIV-infected patients, and how these risks can be evaluated.
Various measures to prevent such transmission are also
suggested.
The Centers for Disease Control (CDC) based in Atlanta,
USA, has issued clear guidelines for prophylactic treatment
for doctors and other medical personnel who are at risk
of acquiring HIV infection after coming in contact with
HIV-infected blood and body fluids. These guidelines,
along with the drugs and dosing regimens, are presented
herewith.
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| What is 'Occupational
Exposure' to HIV infection ? |
Medical personnel caring for HIV-infected
patients may be at risk for acquiring HIV infection through
contact with HIV-infected blood and body fluids. This
is referred to as 'occupational exposure' to HIV.
Apart from HIV, other blood-borne pathogens that may be
occupationally acquired are the hepatitis B and C viruses. |
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| Who is at risk for 'Occupational
Exposure' ? |
| All healthcare personnel (HCP) who come
in contact with blood or bloody fluids of HIV-infected
patients in hospitals or laboratories are at risk for
occupational exposure to HIV. This includes nurses, laboratory
workers, doctors, residents, paramedical staff, emergency
doctors, medical students and others. |
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| What is the risk of occupational
exposure ? |
It should be emphasized that HCP are not
at an extremely high degree of risk of acquiring HIV from
their patients.
The risk varies depending on the type of exposure. A percutaneous
injury refers to an injury resulting from a needle prick,
or a cut with a sharp object. The risk after percutaneous
exposure is estimated to be about 0.3% i.e. 3 out of a
thousand needle pricks may result in HIV infection.
The risk after a mucous membrane exposure is estimated
to be lower; about 0.09%. This includes contact with the
mucous membranes of the eyes, nose and mouth, or contact
with chapped, abraded or inflamed skin.
Any kind of direct contact with concentrated HIV in a
laboratory is also considered risky.
Contact of HIV-infected blood with intact skin for a prolonged
period, or over an extensive area of the skin, may carry
a risk, although isolated skin exposure for a short period
probably does not pose a risk.
Till June 2000, 56 documented cases and 138 possible cases
were reported to the Centers for Disease Control (CDC)
in the USA. Of the documented episodes, the majority of
HCP were percutaneously exposed to HIV-infected blood.
The percutaneous exposures most frequently involved hollow-bore
and solid needlestick injuries; a few involved other sharp
objects.
Most reported occupationally acquired infections have
occurred in nurses and laboratory workers. Percutaneous
and other exposure are also common during surgical procedures.
Factors posing a risk to the surgeon are the length of
the procedure, the volume of blood loss, and whether the
operation involves major vascular or intraabdominal/gynaecologic
surgery. |
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| Which factors influence
the risk ? |
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Various factors increase the risk of acquiring HIV
infection. These include:
- The depth of the injury (in case of a sharp object).
- Whether the device was visibly contaminated with
blood.
- Whether the procedure involved placing a needle
directly in an artery or vein
- Whether the needle was a hollow bore needle or
a solid needle (e.g. suture needle).
- The size of the needle (large versus small gauge)
- The patient's viral load (i.e. amount of HIV in
circulation).
- The amount of blood or infectious fluid involved
in the exposure.
- The duration of the exposure.
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| Which body fluids transmit
HIV ? |
| Blood and bloody fluids are considered
infectious. Potentially infectious materials include semen,
vaginal secretions, CSF, pleural, peritoneal, pericardial,
amniotic fluids or tissue. Exposure to saliva, tears,
sweat, non-bloody urine or faeces is not believed to pose
a risk. |
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| Which are the most frequent
areas of contact for the HCPs ? |
| The most frequent areas of contact are
the hands. Face contacts are common in orthopaedics and
obstetrics. Eye or mucous membrane contacts may occur
in cases where there is splattering of blood. |
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| How can risks be reduced
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There are several preventive measures to reduce the
risk of HIV transmission. These include:
- The use of universal precautions, which also reduce
risk of transmission of other blood-borne pathogens.
- The use of two pairs of gloves by surgeons. The
obstetrician may use barriers such as face shields,
impervious gowns and impervious shoe covers. Goggles
can prevent eye contact.
- Care should be taken during procedures such as
endoscopy, ENT surgery, and other situations where
splattering of blood is anticipated.
- Avoiding recapping of needles
- The use of impervious needle-disposal containers.
- Transport of samples in sealed containers.
Contingency plans for dealing with occupational exposures
in hospitals should be available. These include:
- Protocols for evaluation, counseling and treatment
of occupational exposures.
- Access to clinicians during all working hours.
- Availability of antiretroviral agents on-site or
easily.
- Availability of trained personnel for post-exposure
counseling.
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| How is an occupational
exposure evaluated ? |
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An occupational exposure is evaluated based on the
following factors:
- What is the source material?
- What is the risk of exposure?
- What is the status of the source person/specimen?
(HIV positive, end-stage disease, primary HIV infection,
unknown)
- Is the HCP pregnant?
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| What immediate measures
should be taken after an occupational exposure ? |
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The immediate measures to be taken after an occupational
exposure include:
- Use soap and water to wash any wound or skin site
that came into contact with infected blood or fluid.
- Flush exposed mucous membranes with water
- Irrigate an open wound with sterile saline or disinfectant
solution
- Eyes should be irrigated with clear water, saline
or sterile eye irrigants.
- Report to the concerned authority.
- Counselling
- Use antiretroviral therapy.
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| What is 'post-exposure
prophylaxis ? |
| The term 'post-exposure prophylaxis' (PEP)
refers to treatment of occupational exposures using antiretroviral
therapy. The rationale is that antiretroviral treatment
which is started immediately after exposure to HIV may
prevent HIV infection. |
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| What are the current
guidelines for PEP ? |
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The currently recommended guidelines state that:
- Therapy should be recommended after exposure
- Therapy should be initiated within one to two hours
of exposure, for a period of 4 weeks
- 2- and 3-drug PEP regimens that are based on the
level of risk for HIV transmission represented by
the exposure are recommended
- Reevaluation of the exposed person should be considered
within 72 hours post-exposure, especially as additional
information about the exposure or source person becomes
available
- If the source patient's HIV status is unknown at
the time of exposure, decide whether to give PEP on
a case-to-case basis after considering the type of
exposure and clinical/epidemiological likelihood of
HIV infection in the source
- If a source person is determined to be HIV-negative,
PEP should be discontinued
- Follow-up counseling and HIV testing should be
carried out periodically for at least 6 months (i.e.
at baseline, 6 weeks, 12 weeks and 6 months). It is
estimated that 95% of HCP seroconvert within 6 months
of exposure. The development of HIV antibody is considered
a reliable indicator of HIV infection, and HIV antibody
testing is currently considered the gold standard
for following up exposed HCP. The routine use of direct
virus assays (e.g. HIV p24 antigen or tests for HIV
RNA) to detect infection in exposed HCP generally
is not recommended due to the infrequency of seroconversion
and expense.
- Baseline HIV testing should be carried out to rule
out any existing HIV infection at the time of exposure.
- Potential benefits of PEP must be balanced against
potential toxicities.
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| What are the recommended
regimens for PEP ? |
Basically, 2 types of
regimens are recommended for PEP: a "basic"
2-drug regimen that should be appropriate for most HIV
exposures and an "expanded" three-drug regimen
that should be used for exposures that pose an increased
risk for transmission.
The following algorithm is used to evaluate the level
of risk for HIV transmission posed by a particular exposure.
Accordingly, a basic or expanded regimen may be recommended,
as appropriate.
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