Wednesday 29 June, 2016 13.00 EDT
Managing your health: a guide for people living with HIV
2. HIV … the basics
This chapter explains some basic but complex issues, including how your immune system works and the way that HIV makes you sick. We encourage you to browse these pages to understand more about topics such as CD4+ cells, seroconversion and other key concepts that will also help information in other chapters fall into place.
What is HIV?
HIV stands for human immunodeficiency virus. The term immunodeficiency means a weakened immune system. People who have been infected with HIV are called HIV-positive (sometimes written: HIV+).
HIV is a virus that weakens your immune system, which is the internal system that defends your body against disease. Your immune system is supposed to protect you from infections, but HIV can sneak past it and then attack your body from the inside. If your immune system becomes weak enough, you can become sick from other infections.
What is AIDS?
AIDS stands for acquired immunodeficiency syndrome. If HIV is not treated with anti-HIV drugs, your immune system generally becomes weaker over time. Eventually, you can become sick with a life-threatening infection, at which point you are said to have AIDS.
With proper treatment with anti-HIV drugs, most people with HIV can avoid getting AIDS and stay healthy for a long time.
What is a virus?
Viruses (like HIV) are strange. They are the very simplest and smallest of all living things—even smaller than bacteria and other germs. In fact, it’s hard to say whether viruses even count as living things at all, since they can’t reproduce on their own. To reproduce, viruses need to infect living cells and fool them into making more viruses. These newly formed viruses then go on to infect other cells.
HIV is a virus that can infect cells of the immune system, including the all-important CD4+ cells—the very cells that are supposed to fight off infections. That’s what makes HIV so dangerous.
When describing how viruses like HIV reproduce, we actually use the science-fiction-sounding word replicate. In a way, viruses really are just ultra-tiny robots—machines that do little more than make more of themselves. Unfortunately, in the process, they can cause great damage to the body they’ve infected.
How is HIV transmitted?
HIV infection happens when enough HIV from an HIV-positive person gets into an HIV-negative person’s body. This can’t happen through casual contact, such as shaking hands, sneezing or touching a doorknob or toilet seat. HIV infection only happens when body fluids with a high amount of virus get into the other person’s body. Only five body fluids can contain enough virus to infect someone else: blood, semen (including pre-cum), vaginal fluid, anal fluid and breast milk. Infection can happen during sex, during childbirth and through needle use (by sharing used needles or “works”).
There is little or no risk of HIV being transmitted through unbroken skin. However, transmission can happen much more easily through the mucosal membranes. These are the wet linings of body cavities like the vagina, rectum and urethra (the “pee hole” in a man’s penis or a woman’s vulva). HIV can infect cells in the lining of the vagina, rectum and penis even if the tissues are healthy. Having a sexually transmitted infection like herpes, gonorrhea or syphilis can make it even easier to transmit (or be infected by) HIV. So can any other damage to these tender tissues, which can easily happen during sex.
Sexual activities that can easily lead to HIV transmission are called high risk. High-risk sexual activities include vaginal or anal intercourse without a condom. Some sexual activities, such as oral sex, pose only a low risk of HIV transmission. While these activities can lead to HIV transmission, the chances are much smaller than they are with high-risk activities. Other sexual activities pose no risk for HIV transmission. These include kissing, hugging, mutual masturbation or massage.
HIV can also be transmitted if you share needles or other equipment to inject drugs such as heroin, crack, steroids or hormones.
It is important to be aware of these risks so that you can prevent spreading HIV to your sexual partners or anyone you share drugs with. It is equally important for you to protect yourself from reinfection with HIV, as this could further damage your immune system or expose you to a strain of HIV that is resistant to certain kinds of anti-HIV drugs (see Chapter 10, Treatments).
How do you know if you have HIV?
In order to find out if you have been infected with HIV, you need to have a blood test. This blood test, often incorrectly called an AIDS test, is actually a test for HIV antibodies.
Antibodies are produced by your body as a reaction to infection with HIV. An HIV antibody test looks for the presence of these antibodies in your blood. A needle is inserted into a vein in your arm and a sample of your blood is taken. It is sent to a lab to be tested for the presence of these antibodies. After about three weeks, the test results come back to the office where you had the test done.
However, there are new rapid HIV tests available. The entire process with the new tests, including taking a drop of blood from your finger, along with HIV counselling before and after the test, takes about 20 minutes. The results that you receive from the rapid test are very accurate.
Since HIV antibody tests look for antibodies and not the virus itself, you need to wait to be tested until HIV antibodies are made by your body.
The period of time from when you are infected with HIV to when antibodies appear in your blood is often called the window period. During the window period, the HIV test may give a negative result even though you have HIV. Newer methods of testing are shortening the window period. Talk to your doctor or HIV tester about the window period for the test being used.
A positive test result means that you have been infected with HIV. You can transmit the virus to people if you have unsafe sex or share needles with them. A positive test does not mean that you have AIDS or that you will get it. It does not give you any additional information about the state of your health.
How your immune system works
Germs are all around us (and often inside us). They’re not always bad. Some are even helpful: for instance, your intestinal tract is loaded with “friendly” bacteria that you need for proper digestion.
Many kinds of germs, however, can make you sick—from mild, passing illnesses like a cold, to serious or even fatal infections. Fortunately, your immune system usually protects you from germs by recognizing that don’t belong in your body and destroying them.
Your body’s first line of defence is the skin. The skin covers the outside of your body, acting as a physical barrier to germs. If there are breaks in your skin, even very small ones, they can provide vulnerable spots where viruses and other germs can enter the body.
Your mucous membranes are the soft, wet linings of your mouth, nose, genitals and anus. The mucous membranes also defend your body on the cellular level against germs. This cellular-level defence is called mucosal immunity. But mucous membranes are not a perfect barrier. Small breaks and thinning in these membranes can create entry points into the inside of your body for viruses and germs.
Luckily, there’s far more to the immune system. The immune system is made up of chemicals, cells, tissues and organs. The most important elements are white blood cells. These white blood cells patrol the body, moving through your blood and lymphatic system.
Your circulatory system, made up of your heart and blood vessels, carries blood to all the organs and tissues of the body. Your lymphatic system carries a clear fluid called lymph to different parts of the body. Lymph sweeps germs into the lymph nodes located in your armpits, neck, abdomen and groin. There, immune cells ambush the germs.
When you’re fighting off the flu or other infection, you can often feel swollen lymph nodes in your throat and groin. This is a sign that your immune system is actively fighting the infection.
Different kinds of white blood cells work as a team to recognize and destroy intruding germs. Specialized white blood cells also search for any of your own cells that are already infected. They destroy these cells to prevent infection from spreading further.
CD4+ cells play a central role in the immune system. They’re often described as the quarterbacks or generals of the body’s defensive team or army. If you’re not big on sports or the military, you can just think of CD4+ cells as central to fighting off germs. CD4+ cells help recognize infection. They also co-ordinate all the other parts of the immune system to provide an organized response.
How HIV can make you sick
Unfortunately, CD4+ cells are also one of HIV’s favourite targets. HIV attacks and destroys CD4+ cells, one of the most important parts of your immune system. This eventually leaves your immune system weak and unable to defend you against serious illnesses.
The body fights back by constantly producing new immune cells. However, over time, the virus tends to win out. The immune system becomes less and less able to suppress HIV and other infections. It also becomes less able to control the spread of certain types of cancer cells. When the immune system becomes weakened enough by HIV infection, these other infections can become serious or deadly problems.
If HIV is not diagnosed or is not treated with anti-HIV drugs, it moves or progresses through several distinct phases. Some people progress very quickly, while others live with HIV for years without developing a life-threatening infection.
With HIV treatment now available, most people remain healthy and do not go through these stages.
First stages of HIV infection
Primary infection refers to the time when you’re first infected with HIV. Many people are not aware that they are even infected with HIV at this point. Nonetheless, during this stage the virus multiplies rapidly. Within two to four weeks after infection, you may experience flu-like symptoms such as fatigue, fever, sore throat, swollen lymph nodes, headache, loss of appetite or skin rash. This illness usually lasts less than two weeks, although it can last as long as 10 weeks. (Not everybody has these symptoms, so they’re not a reliable way to tell whether or not you’ve been infected.)
During this period, the immune system is learning to recognize HIV. It has not yet developed killer proteins known as antibodies to attack the virus in any significant way. This means that:
- the amount of virus in your blood may be very high;
- your CD4+ counts may drop until your body responds to the new infection;
- standard HIV tests could show that you are not infected even though you actually are. This is because the tests look for HIV antibodies, which your body hasn’t developed at this stage;
- you can still pass HIV on to someone else. In fact, you are most likely to pass the virus on to others when you’re newly infected, because there’s so much HIV in your body.
When your body develops antibodies to HIV, this is known as seroconversion. This usually happens one to three months after infection. The blood test for HIV, which actually looks for the antibodies, not the virus itself, will only give positive results after you seroconvert.
Around this time, the amount of virus in your blood (known as your viral load) will come back down after the high spike seen during the primary infection period.
Next stages of HIV infection
You may feel perfectly well for a long time during the stage of HIV infection that follows seroconversion. Although your immune system hasn’t eliminated the infection, it is able to more or less hold its own against it, meaning the virus and your body now co-exist in a kind of standoff. Your CD4+ cell counts and viral load will remain relatively stable, although your viral load may go up if you’re fighting off other infections such as a cold or the flu. You will not have symptoms of HIV disease, which is why this stage is sometimes called asymptomatic infection.
This is the longest stage of HIV infection (see graph). In many people, it can last 10 or more years, while in others, it may be a shorter period of time. During the asymptomatic infection phase, HIV is rapidly making copies of itself (replicating) and infecting new CD4+ cells. Your body is trying to counterbalance this loss of CD4+ cells by creating new, healthy ones. As long as your body can replace those CD4+ cells infected by HIV with healthy ones, your immune system will remain strong. In most cases however, if left untreated, HIV eventually starts to win this battle.
The strength of your immune system is measured by your CD4+ cell count (see Chapter 9, Monitoring your health).
As the virus overburdens your immune system, your CD4+ cell count drops and you are at increased risk for developing symptoms of HIV infection. These can include swollen lymph nodes, night sweats, fever, diarrhea, weight loss and fatigue. You may develop infections like thrush or persistent vaginal yeast infections. These are all signs that HIV infection is progressing and requires treatment. For more information on infections associated with HIV infection, see Chapter 12, HIV-related infections and cancers.
If your HIV infection is not treated with anti-HIV drugs, you may progress to the stage known as AIDS. Experts have created a list of AIDS-defining illnesses that are used in the diagnosis of AIDS and in statistics. These illnesses are limited to more serious life-threatening infections, including bacterial infections such as Mycobacterium avium complex (MAC), fungal infections such as Pneumocystis pneumonia (PCP) or cancers such as non-Hodgkin’s lymphoma and Kaposi’s sarcoma (see Chapter 12, HIV-related infections and cancers).
For most people, AIDS is an even more frightening and loaded term than HIV. Before effective anti-HIV drugs were available, progressing to AIDS and eventually death was the inevitable outcome of HIV infection for most people. However, with effective anti-HIV drugs, HIV disease can be controlled and does not progress toward life-threatening illnesses. Anti-HIV drugs can slow down or halt the progression toward AIDS in people with HIV who are healthy and it can also help people who have become sick with AIDS-related life-threatening infections to get better and stay healthy.
The way that we refer to HIV and AIDS reflects this new reality. Many people now refer to HIV disease or chronic HIV infection, reflecting the fact that AIDS is now a much less common outcome of HIV infection. The terms HIV disease or chronic HIV infection can describe anyone, treated or untreated, at any stage of infection, neatly sidestepping the HIV-versus-AIDS question.
HIV: The Basics – A plain and simple look at HIV and the immune system, staying healthy and protecting yourself and others
The Epidemiology of HIV in Canada – a summary of the HIV statistics for Canada
Information on the biological factors that can increase or decrease the risk of sexual transmission of HIV:
These and many other relevant resources can be accessed through the CATIE Ordering Centre or by calling CATIE at 1-800-263-1638.