As public awareness about prevalent diseases like HIV increases, there is still some confusion about medical terms and the meaning of some of these words. Many people know what HIV/AIDS is in a broad sense, what it happens in the body to some extent and how it is contracted. Given the prevalence of HIV/AIDS these days, it is important to know many of the related medical terms that are widely used. Even if you do not have the diseases, understanding the meaning of these words will help you better relate to friends, family and colleagues who are living with HIV or have AIDS.
First and probably most importantly, HIV is not the same as AIDS. If you have HIV, you do not necessarily have AIDS as yet. HIV stands for human immunodeficiency virus – the virus that plays a role in AIDS. HIV infection can eventually lead to AIDS – a state where your immune system is seriously compromised. The time from contracting HIV to developing AIDS varies for every person with HIV infection. For some it can take just a few years while others may live with HIV infection for decades before reaching the point of AIDS. While medication can slow the progression of the infection and treat some of the other diseases that develop with HIV/AIDS, as yet there is no cure for HIV/AIDS.
AIDS Defining Illness
The term AIDS-defining illness/disease simply means that a person with HIV infection has developed conditions that marks the onset of AIDS. To put it in greater perspective, there are some diseases that are not commonly seen in the general public. This is because our immune systems protect us. But people with a weakened immune system are more likely to suffer with these diseases. Therefore once it is seen in a person living with HIV, then a doctor is able to verify that the the point of AIDS has been reached.
Antiretroviral therapy (ART) is the use of antiretrovirals to treat HIV infection since the virus is a retrovirus. These drugs slow down the progression of the infection by hampering replication of the virus through different mechanisms. Antiretrovirals (ARVs) are not a cure for HIV/AIDS. It is the main type of HIV medication that is widely available and recommended for the management of HIV/AIDS. Another commonly used term is HAART which stands for highly active antiretroviral therapy. It is where several ARVs are used simultaneously for HIV infection since collectively these drugs are more effective in achieving its goal.
CD4 Cell Count
There are several different types of white blood cells in the human body which are also known as leukocytes. These cells are part of the immune system and play an important role in protecting the body against foreign invaders. One group of these cells are T-lymphocytes and a subgroup of these lymphocytes is the CD4+ T-lymphocyte. It is this specific lymphocyte that HIV targets. The virus enters these cells, replicate and destroy the cell. As HIV progresses, the CD4+ T-lymphocyte cell count decreases. Therefore the CD4 count is both an indication of the progression of HIV infection and the degree to which the immune system is compromised.
There are different strains of HIV. In fact this characteristic is one of many that differs HIV from many other viruses. There is a relatively large degree of variance in its genetic structure. Most people are infected with one strain of HIV. But sometimes a person can be infected with two strains of the virus. For this reason it is referred to as “superinfection”. Initial HIV infection does not mean that you have complete protection against any other HIV infection. The genetic material of different HIV strains can combine within a T-cell and form what is known as a recombinant virus. Superinfection negatively affects the health outcome of HIV-infected people.
An HIV vaccine would be able to provide a person with immunity against the virus. This means that it could prevent infection if a person who has been vaccinated is exposed to the virus. As yet there is no viable HIV vaccine available for public use. Several vaccines have undergone different clinical trials – some have been withdrawn and the trials canceled while others are still being tested. It is hoped that someday a viable HIV vaccine will be available which can be used as part of mass immunization programs to protect people from contracting the infection. It would ultimately play a positive role in reducing the incidence and prevalence of HIV infection throughout the world.
Immunocompromised means that your immune function is compromised. Your immune system is weakened and may not be able to protect you in the way it should. This is in contrast to a person with a healthy immune system. The term ‘immunocompetent’ means that your immune system is healthy and able to protect you effectively. Although individual immunity can vary from person to person and during the course of life, a person who does not have any predisposing disease that weaken the immune system is said to be immunocompetent. It is not only HIV infection that compromises your immune system – it can happen with a host of different diseases, prescription drugs and lifestyle factors.
An opportunistic infection means that microorganisms that would otherwise not cause an infection in a healthy person, or rarely does so, is more likely to cause an infection with a weakened immune system. The human body is exposed to thousands of different microorganisms in the course of daily life. Some are in the environment and some live on or inside us. However, many are not pathogenic (disease-causing) or can be suppressed due to the activity of a healthy immune system. However, when the immune system is weakened, these microorganisms take the opportunity to replicate and infect us thereby causing disease. It is these opportunistic infections that kills a person with AIDS and not HIV itself.
Post-exposure prophylaxis (PEP) is a combination of ARV drugs that are administered to a person who has come in contact with HIV infected body fluids. PEP may be able to prevent HIV infection. It is a short duration treatment that should be taken within a few hours after exposure. Starting PEP later than 72 hours after exposure may not be as effective. This treatment is widely used in rape victims and health care professionals who have a needle stick injury. It is typically used for 28 days but it is not a guarantee that HIV infection can be prevented.
The body develops antibodies against HIV once the virus is in the system. The presence of these antibodies is the basis of many of HIV tests. A positive result for HIV antibodies means a person is infected with the virus. However, a negative result does not necessarily mean that a person is not infected with HIV. The human body takes anywhere between 3 to 12 weeks to form these antibodies to a level where it is detectable by common HIV tests. Seroconversion is the term used for when these antibodies have formed and can be detected. The period between infection and seroconversion is known as the “window period” during which you have been infected but it cannot be detected with antibody testing.
The viral load is the amount of virus in your blood. Normally there is no HIV in your bloodstream if you are not infected with the virus. But in people who have been infected, the quantity of virus gradually increases over time. The viral load is measured by the amount of the viral genetic material in the blood. With HIV, this is RNA and it is expressed as copies per milliliter (mL). Monitoring the viral load is an important tool in HIV management, along with the CD4 count discussed above. It is able to tell your doctor how the infection is progressing or how well your current drug regimen is working.