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HIV is considered to be a fragile virus when exposed to air
and room temperatures. Hepatitis B (HBV) and hepatitis C (HCV)
are both considered "stronger" viruses that can remain infectious
for a longer period of time. When these viruses are outside
the human body, much depends on environmental factors such
as heat, cold, exposure to oxygen, etc.).
HIV transmission occurs through infected blood and body fluids.
Transmission occurs primarily through infected blood, semen,
vaginal secretions or breast milk. Sweat, tears, saliva,
urine and feces are not capable of transmitting HIV unless
visibly contaminated with blood. In settings such as hospital
operating rooms, other fluids, like cerebrospinal fluid, synovial
fluid, pleural fluid, pericardial fluid and amniotic fluid
may be considered infectious if the source
is HIV positive. These fluids are generally not found outside
the hospital setting, so the most common fluids -- blood,
semen, vaginal secretions and breast milk - are considered
infectious in the "real world."
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Case Study
#1
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Mr. R. is a middle-aged married male computer salesman
who was transported to the ED after being found unresponsive
in his apartment by a neighbor. Following a thorough
exam the provider suspected a possible drug overdose,
which was confirmed when a urine drug screen was positive
for cocaine. Once stabilized, the staff offered him
an HIV test. Mr. R. adamantly refused the test saying
that he did not have any risk factors. The provider
suspected this was not true and proceeded to perform
a social history. Eventually, the provider was able
to solicit answers that indicate Mr. R. is at risk for
HIV: he has been sexually active since high school and
has not always used condoms; while he is primarily heterosexual
and has been married for almost 15 years, he has occasionally
located men on the internet that he met for dates; he
has never used intravenous drugs, but does share straws
when using cocaine; he was incarcerated for assault
when he was younger, and while in jail had used a common
needle to give himself a tattoo.
Mr. R. thought that since he had only used drugs with
people he knew and had sex with healthy looking men
he did not have risk factors for HIV. He also thought
that someone would have found out he was HIV positive
during a recent hospital admission when he had labs
drawn daily prior to and after major surgery.
The provider convinced Mr. R. that he should have an
HIV test based on the results of his assessment. He
provided him with education focusing on routes of transmission
and appropriate barrier use. He explained the risk of
having unprotected sexual relations and the fact that
you cannot tell someone has HIV/AIDS by the way they
look. The test results were negative, and the provider
stressed the importance of retesting if he engaged in
more high risk behaviors.
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HIV is transmitted through very specific ways:
- Unprotected anal, vaginal and oral intercourse;
- Sharing needles or other injection equipment;
- A mother passing the virus to her baby either
before or during birth;
- An infected woman breastfeeding her infant;
- Transfusion of HIV-infected blood or blood products
(prior to 1986);
- Accidental needlestick injuries, or other sharps
injuries, or infected body fluid coming into contact with
the broken skin or mucous membranes of another person (as
with healthcare workers);
- Sharing razors or toothbrushes, if infected blood from
one person is deposited on the toothbrush or razor, and
the blood enters the bloodstream of another person.
HIV transmission may occur during practices such as tattooing,
blood-sharing activities such as "blood brothers" rituals,
or any other type of ritualistic ceremonies where blood is
exchanged or unsterilized equipment contaminated with blood
is shared. HIV can also be transmitted from mother to infant
during the birth process.
HIV transmission may also occur in occupational settings.
Workplace exposures occur through an unintentional needlestick
injury or potentially through a splash with potentially infectious
blood or blood-contaminated material. This will be discussed
later in this course.
There are also isolated cases of transmission from healthcare
workers to patients. To date, there were three instances where
transmission of HIV may be related to the HIV-infected healthcare
provider treating the patient. At least one of these cases
occurred prior to the implementation of strict equipment disinfection.
However, the CDC reports that there has been one case of confirmed
HIV infection from healthcare worker to patient; that case
involved a dentist. Occupational exposure will be covered
in detail in Part 3 of this course.
Biting poses very little risk of HIV transmission. The possibility
only exists if the person who is biting and the person who
is bitten have an exchange of blood (such as through bleeding
gums or open sores in the mouth.) Bites may transmit other
infections, and should be treated immediately by thoroughly
washing the bitten skin with soap and warm water, and disinfecting
with antibiotic skin ointment.
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Case Study
#2
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| Ms. H. is a 20 year old African American female. She
has been sexually active since she was 15, and has been
treated several times in the past for sexually transmitted
diseases (STDs). She recently presented to the STD clinic
with c/o painful open sores on her vaginal area. She had
several partners in the past two months, but she did not
see any similar sores on any of them. The provider told
Ms. H that it is important to use barriers when having
sex to prevent STDs and also HIV. She explained that it
increases the possibility of infection when someone has
a break in their skin or mucous membranes, allowing the
virus to pass more easily from one person to another.
She also explained that, while most STDs can be treated,
HIV has no cure. Ms. H. agreed to be tested for HIV as
well as STDs. Unfortunately, her test results showed that
she had genital herpes, but was negative for HIV. Her
provider reminded her that she could have future outbreaks
of herpes that would leave her vulnerable to infection
with HIV because of the open areas on her skin. She was
provided with both male and female condoms before leaving
the clinic, and encouraged to tell her partners about
the herpes before having sex. |
The viral load is one of the predictors of how infectious
is an HIV-positive person; viral load indicates how much HIV
is present in the bloodstream. Studies show a clear connection
between higher viral load in the blood and increased transmissibility
of HIV.
Prior to the availability of a test for HIV antibodies in
1985, HIV was transmitted by:
- Artificial insemination;
- Blood or blood products transfusions;
- Organ transplants.
Testing has almost completely eliminated these risks for
transmission in developed countries.
The CDC has estimated the following probabilities of infection
following one exposure to HIV:
- Contaminated blood transfusion (prior to 1986) 95%
HIV infection rate:
- One intravenous syringe or needle exposure 0.67%
- One percutaneous exposure (e.g. a needlestick) 0.4%
- One episode of receptive anal sexual intercourse 0.1%-3%
- One episode of receptive vaginal intercourse 0.1%-0.2%
- One episode of insertive vaginal intercourse 0.03-.09%
Continue on to Transmission
of HIV, Con't.
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