HIV/Aids is caused by the Human Immunodeficiency Virus (HIV). HIV is mainly transmitted through sexual intercourse, but can also be passed down from mother to child, acquired via blood transfusion with infected blood, or other methods. Once a person is infected, the virus remains in the body for life. There is no cure for HIV/Aids, but there are drugs that help control the virus, enabling people with symptoms of HIV to live full and healthy lives. There are also various methods to help prevent the spread of the disease.
HIV/AIDS is caused by the Human Immunodeficiency Virus (HIV).
The virus is mainly transmitted through sexual intercourse but can also be passed down from mother to child during pregnancy, childbirth and breastfeeding, or acquired via blood transfusion with infected blood, the sharing of needles (e.g. during drug use) or through needle-stick injuries (if you’re a healthcare worker, for example).
Once you’re infected, the virus remains in your body for life. Although there currently isn’t a cure for HIV, antiretroviral treatment (ART) helps to keep the virus under control and enables people living with HIV to lead a full, productive life.
In addition, we now also know that ART helps to prevent the onward transmission of HIV – i.e. if you’re HIV-positive, and on ART, there’s a lower risk of transmitting the disease to others.
Acquired Immune Deficiency Syndrome (AIDS) is a chronic, life-threatening disease caused by the HI virus. The virus attacks and gradually destroys the immune system (which helps the body to defend itself against infection and disease). Without treatment, people with HIV become susceptible to a variety of opportunistic infections – so called because they take advantage of the body's weakened immune system.
These infections are unlikely to occur in people with healthy immune systems. AIDS develops during the final stages of HIV infection and is characterised by a CD4 cell count of less than 200 cells per mm3 or the presence of any AIDS-defining condition.
Strictly speaking, AIDS isn’t a specific illness but a collection of many different conditions that manifest in the body (or in specific parts of the body), because the HI virus has weakened the immune system to such an extent that it can no longer fight disease.
It may take years for the immune system to deteriorate to such an extent that someone living with HIV becomes ill and is diagnosed with AIDS. During this time, they may look and feel perfectly well.
This explains why so many people are unaware that they’re infected with HIV. But even though they feel healthy, they can still transmit the virus to others.
The exact origin of the HI virus has been a topic of much debate over the past few decades. We now know that, at some point in the 1970s, the virus began spreading across the globe, although it first came to the attention of medical authorities and researchers in the early 1980s. The virus was, however, born much earlier.
Recognition of the virus in the 1980s marked the beginning of the epidemic as we know it today. In South Africa, the epidemic started to explode in the early 1990s and, by the year 2000, more than 20% of the population had been infected.
Acquired Immune Deficiency Syndrome (AIDS) is caused by one of two viruses: HIV-1 or HIV-2.
HIV-1 is the predominant virus in most parts of the world, including South Africa, while HIV-2 is most commonly found in West Africa.
The two HI viruses are retroviruses that insert their genetic material into the DNA of the cells of the person they’ve infected. In this way, they can infect you for the rest of your life, while decreasing your resistance to infections and certain cancers.
The HI virus, which is circular in shape, does something that no other virus does: it attacks your CD4 cells (the most important immune cells in your body), uses them to reproduce, and then destroys them.
The immune system weakens as more CD4 cells are killed, eventually progressing to AIDS.
The choice of antiretroviral treatment (ART) for HIV-2 differs from that for HIV-1, which is why it’s important to get tested properly. ART is designed to interfere with the virus’s ability to reproduce, slowing down the progression of HIV to AIDS.
While it’s impossible to look at someone and know whether they have HIV, the majority of people will have some symptoms about three weeks after they become infected with the virus.
This is called “seroconversion illness” (or primary or acute HIV infection) and coincides with the production of antibodies to the virus. Antibodies are molecules that recognise and attach to organisms invading the body with the aim of destroying them.
HIV antibodies become detectable in the blood during seroconversion, and standard HIV tests (rapid test or ELISA) are used to determine whether they are present. The period after infection, but before the production of antibodies, is called the window period. During this time, an HIV test may be negative.
During the seroconversion illness, symptoms usually last 1–2 weeks and may include the following:
After experiencing these initial symptoms, most people don’t have any other symptoms for many years. This is why HIV/Aids is often called the “silent epidemic” and why getting tested is so important. Only a blood or fluid sample can reveal the presence of the virus.
When symptoms associated with the advance of HIV to AIDS occur, they appear roughly in the following order:
In children, the order of symptoms and the symptoms themselves differ slightly, and include:
HIV is regarded as a chronic disease because people living with HIV can live healthy and productive lives for many years before getting sick.
However, if you’re HIV-positive, you’ll need ongoing monitoring and regular clinic visits to determine the progression of the disease.
The length of time it takes for HIV to become AIDS varies from person to person and depends on your access to treatment, health status and health-related behaviours.
HIV/AIDS is treated with antiretroviral treatment (ART) and medication that helps to keep opportunistic infections (diseases that occur in people with suppressed immune systems) under control.
Without treatment, almost everyone with HIV will get AIDS. ART isn't a cure, but it can control the virus so that you can live a longer, healthier life and reduce the risk of transmitting HIV to others.
The goals of ART treatment are to:
ART involves taking a daily combination of HIV medicines, called an HIV regimen. These HIV medicines prevent the virus from multiplying (making copies of itself), which reduces the amount of HIV in the body.
Having less HIV in your body gives your immune system a chance to recover and fight off infections and cancers. It also allows you to remain symptom-free for longer.
ART is recommended for anyone who has HIV, without delay, regardless of how long they’ve had the virus or how healthy they are. If left untreated, HIV will attack the immune system and eventually progress to AIDS.
ART is strongly advised when the CD4 count is less than or equal to 350 cells per mm3, or if you have an AIDS-defining illness, irrespective of your CD4 count.
Certain groups of people, such as children under the age of five, those with HIV and TB and those with HIV and hepatitis, should receive ART as soon as possible.
If you feel unsure about taking the medicines, talk to your doctor or clinic nurse about your concerns. It might also help to talk to someone else who is using ART.
Factors to consider when starting ART:
PrEP, PEP and the race to find an HIV vaccine
If you’re HIV-negative but at ongoing risk of being exposed to HIV, it’s worth learning more about pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP).
You might also be interested to know if researchers are making progress in developing an HIV vaccine.
Pre-exposure prophylaxis (PrEP)
Prophylaxis refers to the prevention or protective treatment of disease. The WHO now recommends that people who are at substantial risk of getting HIV infection should be offered preventative antiretroviral treatment (ART), called pre-exposure prophylaxis (PrEP).
High-risk groups include sex workers, men who have sex with men, adolescents or adults engaging in condomless sex, or the HIV-negative partners of those who are HIV-positive. A drug called Truvada (a combination of emtricitabine and tenofovir disoproxil fumarate, which is licensed in South Africa for this purpose) can reduce the risk of contracting HIV by at least 90% if taken every day.
In September 2017, the Higher Education and Training HIV & AIDS (HEAIDS) national programme also announced that Truvada will be made available to university and college students across South Africa.
If you’re using Truvada to limit your risk of getting HIV, it’s important to use the drug in combination with other safer sex practices (e.g. using a condom). Make sure you still get tested for HIV every three months and talk to your doctor or clinic nurse if you experience any side effects.
You should also remember that PrEP becomes effective only after 7-20 days of taking the medicine. It takes around 7 days for the drug to reach rectal tissue, and around 20 days for the drug to reach tissues of the cervix and vagina.
PrEP should be taken for as long as you’re considered “high risk” and must be continued for 28 days after your last potential HIV exposure. It shouldn’t be taken if you think you may be HIV-positive (for example, if you’re still in the window period) or definitely are HIV-positive. Tests will be carried out before starting PrEP to ensure that you’re HIV-negative.
In the context of HIV, post-exposure prophylaxis (PEP) refers to ART that’s given to someone to help prevent HIV infection after being exposed to the virus.
Healthcare workers who are accidentally exposed to HIV through, for example, a needle-prick accident, should start taking ART as soon as possible after the incident, but no later than 72 hours after exposure.
The drugs must be taken for 28 days and you should see your doctor every two weeks, six weeks and three months after the exposure for HIV testing. Tests for hepatitis B and C, as well as syphilis, should also be done.
PEP isn’t needed if the source patient was HIV-negative. It’s also contraindicated if you’re HIV-positive. If this is the case, you should be on ART.
From analysing thousands of accidental exposures in healthcare workers, it’s been calculated that even though the risk of getting HIV infection from such an accident is quite low (0.3% of cases), taking ART reduces the risk of infection by about 80%.
The South African Government now also funds ART in the context of rape and women who have been raped should start ART as soon as possible.
Note that PEP may be difficult to obtain outside of large hospitals. If you’ve been raped, you can get in touch with a rape centre in your area or ask the local police to point you to a facility where you’ll be assisted.
A doctor or clinic nurse will assess your risk of HIV infection before starting treatment with PEP.
The race to find a vaccine
The first HIV vaccine clinical trial kicked off in Maryland, USA, in 1987.
Since then, numerous experimental vaccine trials have been conducted but none have proven effective. The first-ever vaccine to show efficacy was tested during the RV144 trial in 2009.
The trial consisted of over 16,000 participants in Thailand who received a combination of two vaccines – AIDSVAX and ALVAX. These vaccines were based on HIV strains commonly circulating in Thailand.
A total of six injections were given over six months and participants were followed up for three years. The vaccine lowered the rate of HIV infection by 31% when compared to a placebo. It was the first vaccine trial to appear effective.
There are two vaccine trials currently running in South Africa: HVTN702 is testing a vaccine to protect against the subtype C HI virus prevalent in southern African populations. The vaccine used in this trial is a modified version of the vaccine used in the RV144 trial.
It started in late 2016 and results are expected in 2020. The HVTN702 trial is a phase III trial, which means that, if successful, the drug qualifies to be licensed for medication.
A new vaccine trial was launched in 15 sites across South Africa at the end of 2017. The HVTN705 study involves a mosaic vaccine that targets different strains and sub-types of HIV-1.
It will be tested on 2,600 HIV-negative women between the ages of 18 and 35 who are at risk of HIV infection. Results are expected in 2021 but, even if the trial is successful, further studies will be required. It could take several years before a vaccine becomes available.
Other preventative methods on the horizon
Other preventative methods that are in the research pipeline include vaginal rings, gels and tablets that release antiretroviral medication to reduce the risk of getting HIV from others. None of these have been approved for use as yet.
The US National Institutes of Health (NIH) have also recently launched a trial to test a preventative injection of a drug called cabotegravir. The trial will establish whether a two-monthly injection will reduce the risk of contracting HIV.
Some 3,200 women in southern and eastern Africa, including South Africa, are participating in the trial. Half of the women will take Truvada, while the other half will receive the injection every few months. The study will run for three years and will then assess which group has fewer HIV infections.
Classes of drugs
A growing number of drug classes are being used to treat HIV. These drugs work against the virus in different ways and at different points in the growth cycle.