HIV病毒和其引起的疾病AIDS的生物学特点。影响这一疾病的传播和预后的社会、经济和政治因素。科学研究和治疗手段的发展情况。关于艾滋病的恐惧和希望的来源。(想预览课程论坛上已有的材料，请前往@AIDSFAH或#AIDSFAH)
02.04 - Non-Sexual Transmission of HIV
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來自 University of Michigan 的課程
AIDS：恐惧与希望
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從本節課中
Unit 2 - Transmission, Gender, Politics
Transmission, Gender, More Memories
與講師見面
Richard Meisler, Ph.D.Lecturer
Department of American Culture, University of Michigan
Today's topic is the non-sexual transmission of HIV.
Here's a list of the non-sexual modes of transmission.
Blood transfusion, and the use of blood products.
Injection drug use with contaminated equipment.
Accidental needle sticks in health-care settings.
And mother-to-child transmission.
I've placed mother to child transmission at the end of
the list not because it's the least important.
In fact, it's very important.
I listed the other three modes first because they have something in common, and
understanding how they transmit HIV is conceptually very simple.
We know that transmission means that HIV from an outside source
has reached the bloodstream of a new person.
When we discuss sexual transmission we needed to understand how the HIV would
gain access to the blood through mucus membranes or damaged tissue.
In these three cases, the first three items on our list,
the HIV is introduced directly into the blood.
The transmission of HIV through transfused blood, or
blood products, is of interest mainly for historical purposes.
The blood supply all over the world now is carefully screened for HIV.
But when the AIDS epidemic began, its cause was unknown.
It took several years for scientists to identify HIV as the cause.
And then it took some time for a test for HIV to be developed.
During that interim period, the blood supply was contaminated, and
some patients who received blood transfusions were infected.
The case of hemophiliacs was even more widespread and dramatic.
Hemophilia is an inherited bleeding disease.
When the AIDS epidemic started in the U.S.
in the 1980s, the standard treatment for hemophiliacs was to
give them a blood product that was prepared from the blood of many donors.
This blood product was contaminate, contaminated with HIV and
almost every hemophiliac who received it was infected with HIV.
But again the blood supply and blood products are now quite safe.
A problem that has not been solved is the use of
contaminated equipment by injected drug users.
It is common worldwide for drug users to share needles and syringes.
This is an extremely efficient way for HIV to spread.
The blood from an infected user may well have a high viral content.
And it will be injected directly into the bloodstream of one or more other people.
Later in the course we will talk about risk reduction strategies,
like needle exchange programs.
And we will also talk about the nature of addiction which is central to
understanding the epidemic.
Let's move on now to another mode of transmission that
involves introducing HIV directly into the blood stream of a recipient.
In healthcare settings, workers use protective gloves, yet they also use
sharp instruments like needles and scalpels that easily penetrate the gloves.
There are millions of instances of using these instruments safely, but
there are inevitably some events in which a healthcare worker is accidentally cut
by a sharp instrument that is contaminated with HIV infected blood.
Almost all health care facilities in medically advanced countries have well
defined procedures for
the immediate treatment of workers who are put at risk by needle sticks.
They involve a course of antiretroviral drugs
that radically decreases the chances of HIV infection.
And they generally work, though there are rare exceptions.
That brings us to mother-to-child transmission.
This happens in several ways.
During pregnancy, HIV can cross the placenta and enter the baby's bloodstream.
This risk can be reduced if the mother is in treatment and
her viral load is reduced.
The baby can also be infected during birth.
The birth pro, process can produce abrasions and
cuts that may also come into contact with the mother's blood.
This is another root of infection.
It too can be reduced if the mother is in treatment and
if the baby is given a short course of drug treatment right after birth.
Lastly, the breast milk of an infected mother can contain HIV and
a baby who nurses can become infected.
I'll mention a few other rare non-sexual modes of transmission.
In some cultures, adults pre chew food for infants.
In rare instances, blood from an infected adult's mouth
can infect the baby who eats the pre chewed food.
People wonder whether being bitten by a person with HIV,
or having such a person spit on them presents a risk.
There have been a few documented cases of biting that have led to infection,
but they involve to severe trauma and
extensive tissue damage, and a lot of blood.
There are no documented cases of transmission by spitting.
Lastly, if a person's mucous membranes or
broken skin comes into contact with infected blood or
other bodily fluids, it is extremely rare for that person to be infected.
That does it.
I think we've covered every mode of HIV transmission as well as talking about
quite a few ways, sexual and nonsexual, that HIV is not transmitted.
