Human immunodeficiency virus mostly regarded as HIV is a viral disease that attacks the immune system, which is the body security against foreign bodies.
In the pathophysiology of HIV, we will understand how untreated HIV infects and kills CD4 cells, making the body prone to other diseases
Before the introduction of antiretroviral drugs, HIV is a nightmare to the world and has led over 30 million people to early grave.
This pathogen is spread by contact with certain bodily fluids of a person infected with HIV, most commonly during unprotected sex.
Routes of HIV transmission in the pathophysiology of HIV
- vaginal and rectal fluids
- breast milk
Stages of HIV infection
In the pathophysiology of HIV, there are three distinct stages involved namely:
1st stage (acute HIV infection)
2nd stage (chronic HIV infection)
3rd stage (AIDS [Acquired Immune Deficiency Syndrome])
In the early stage of HIV, infected People have a large amount of this virus in circulation in their blood thus are very contagious.
Although, flu-like symptoms may be experienced in some people which is the body’s natural response to the virus.
In most cases such symptoms are usually neglected and some people remain asymptomatic (no symptom) unless diagnosed.
This early or 1st stage is followed by the chronic HIV infection stage which can also be regarded as clinical latency. Here, HIV is still active but reproduces at very low levels and most people remain asymptomatic during this stage.
The chronic HIV infection period may last a decade or longer (10 years or more), but some may progress faster. That is why is of utmost importance you get tested in frequent times.
At the end of this stage, the amount of HIV in the blood (called viral load) goes up and the CD4 cell count goes down.
The person may have symptoms as the virus levels increase in the body, and the person moves into 3rd stage which is the detrimental stage.
Although the god news is, if you follow the guide lines as approved by WHO that will be given to you in this article “pathophysiology of HIV” you can never progress to this detrimental stage called AIDS (Acquired Immunodeficiency Syndrome)
This 3rd stage is the most severe stage of HIV infection. People with AIDS have such badly damaged immune systems that they get an increasing number of severe illnesses, called opportunistic infections regardless of their CD4 count.
Here, the number of their CD4 cells falls below 200 cells per cubic millimeter of blood (200 cells/mm3). (In someone with a healthy immune system, CD4 counts are between 500 and 1,600 cells/mm3.) OR
Without HIV medicine, people with AIDS typically survive about 3 years. Once someone has a dangerous opportunistic illness, life expectancy without treatment falls to about 1 year.
HIV medicine can still help people at this stage of HIV infection, and it can even be lifesaving. But people who start ART soon after they get HIV experience more benefits—that’s why HIV testing is so important and can never be over emphasized.
Pathophysiology of HIV and Symptoms
The symptoms of HIV and AIDS vary, depending on the stage of infection.
1st stage (Acute HIV Infection)
The acute HIV infection may present symptoms for few weeks which can be so mild that you might not even notice them. They may include:
- Muscle aches and joint pain
- Sore throat and painful mouth sores
- Swollen lymph glands, mainly on the neck
- Weight loss
- Night sweats
In the 2nd stage of infection,
HIV is still present in the body and in white blood cells. However, many people may not have any symptoms of infection during this time. This stage can last for many years if you are not receiving antiretroviral therapy (ART). Although if symptoms are available they will be similar to that of the acute stage.
The 3rd stage AIDS (acquired immunodeficiency syndrome)
Untreated, HIV typically turns into AIDS in about a decade or more
The signs and symptoms of some of these infections may include:
- Recurring fever
- Chronic diarrhea
- Swollen lymph glands
- Persistent white spots or unusual lesions on your tongue or in your mouth
- Persistent, unexplained fatigue
- Weight loss
- Skin rashes or bumps
- Different opportunistic infections like tuberculosis
Risk factors on the pathophysiology of HIV
One is at the greatest risk of contracting HIV if you:
- Are promiscous Use a new latex or polyurethane condom every time you have sex. Anal sex is more risky than is vaginal sex. Your risk of HIV increases if you have multiple sexual partners.
- Infected with an STD Many STDs produce open sores on your genitals. These sores act as doorways for HIV to enter your body.
- Use IV drugs People who use IV drugs often share needles and syringes. This exposes them to droplets of other people’s blood.
Pathophysiology of HIV
Viruses generally are non living thus, cannot replicate without a host, and can only do so inside a living cell. Considering the viral structure, viruses lack the complex components present in bacterial or human cells, so HIV is not an exemption.
One similarity of a virus to bacterium and human is that it possesses genetic material that contains all the information needed to build and maintain an organism.
In humans and bacteria, this is called deoxyribonucleic acid (DNA), where as in viruses such as HIV, genetic data is organised into single strands; this is called ribonucleic acid (RNA) which is protected by capsid.
Outside the capsid are enzymes the virus uses to infect its host and replicate. These structures are surrounded by an envelope comprising glycoproteins, which help the virus identify and bind to its target cell.
After the virus enters the body, there is a period of rapid viral replication, leading to an abundance of virus in the peripheral blood.
During primary infection, the level of HIV may reach several million virus particles per milliliter of blood.
The human immune system has many vital cells that fight infection and destroy abnormal cells; this includes lymphocytes called T-cells, which determine the immune system’s response to foreign antigens.
HIV targets and infects a particular type of T-cell called CD4 ‘helper’ cells. These are so called because they do not kill or neutralise foreign antigens but, instead, signal and recruit other immune cells to do so.
The virus mars the function of the CD4 cells, turning them into factories that produce multiple new copies of the virus.
Once infected, CD4 cells develop a much shorter lifespan and are eventually destroyed. The cytotoxic T cells accounts for CD4+ T cell depletion, although apoptosis may also be a factor.
The CD8+ T cell is also an essential antibody in the pathophysiology of HIV. Its response is thought to be important in controlling virus levels.
During the chronic phase, the consequences of generalized immune activation coupled with the gradual loss of the ability of the immune system to generate new T cells appear to account for the slow decline in CD4+ T cell numbers.
Summary of how HIV invades the CD4 cells in the pathophysiology of HIV
Binding and entry –
The virus seeks out the CD4 cell and attaches itself to receptors on the cell’s outer membrane, it then fuses itself to the cell and releases viral RNA and enzymes into it
Reverse transcription –
The virus converts its single-stranded viral RNA into double-stranded DNA using an enzyme called reverse transcriptase
The virus integrates its newly created viral DNA into the CD4 cell’s nucleus using an enzyme called integrase; by integrating its genetic instructions, it invades the CD4 cell
The CD4 cell starts to build new copies of the virus; this process can sometimes be clumsy, causing mutations and variations in the new virions
Budding and maturation –
The new HIV virions migrate towards the outer membrane of the CD4 cell. An enzyme called protease helps convert the immature virions into mature, infectious virions.
They then push themselves out of the cell, which is called budding, and seek out other CD4 cells to repeat the process
A vigorous immune response eventually controls the infection and initiates the 2nd stage or clinically latent phase or chronic HIV infection.
However, CD4+ T cells in mucosal tissues remain depleted throughout the infection, although enough remain to initially ward off life-threatening infections.
Continuous HIV replication results in a state of generalized immune activation persisting throughout the chronic phase.
Immune activation, which is reflected by the increased activation state of immune cells and release of pro-inflammatory cytokines, results from the activity of several HIV gene products and the immune response to ongoing HIV replication.
Another cause is the breakdown of the immune surveillance system of the mucosal barrier caused by the depletion of mucosal CD4+ T cells during the acute phase of disease.
This results in the systemic exposure of the immune system to microbial components of the gut’s normal flora, which in a healthy person is kept in check by the mucosal immune system.
Eventually, the minimal number of CD4+ T cells necessary to maintain a sufficient immune response is lost, leading to AIDS.
The virus, entering through any route, acts primarily on the following cells:
- CD4+ T-Helper cells(main target cell)
Certain endothelial cells-
Central nervous system-
- Microgliaof the nervous system
- Neurones– indirectly by the action of cytokines and the gp-120
Prevention of HIV in the pathophysiology of HIV
There is no vaccine to prevent HIV infection and no cure for AIDS. But you can protect yourself and others from infection through:
Use treatment as prevention (TasP).
If you’re living with HIV, taking HIV medication can keep your partner from becoming infected with the virus. Using TasP means taking your medication exactly as prescribed and getting regular checkups.
Consider post-exposure prophylaxis (PEP) if you’ve been exposed to HIV
If you think you’ve been exposed to the VIRUS, Taking PEP as soon as possible within the first 72 hours can greatly reduce your risk of becoming infected with HIV. You will need to take medication for 28 days.
Use a new condom every time you have sex
Use a new condom every time you have anal or vaginal sex. Women can use a female condom
Consider pre-exposure prophylaxis (PrEP)
The combination drugs emtricitabine plus tenofovir (Truvada) and emtricitabine plus tenofovir alafenamide (Descovy) can reduce the risk of sexually transmitted HIV infection in people at very high risk.
Tell your sexual partners if you have HIV
It’s important to tell all your current and past sexual partners that you’re HIV-positive. They’ll need to be tested.
Use a clean needle
If you use a needle to inject drugs, make sure it’s sterile and don’t share it.
If you are pregnant, get medical care right away
If you are HIV-positive, you may pass the infection to your baby. But if you receive treatment during pregnancy, you can significantly cut your baby’s risk.
Consider male circumcision
There’s evidence that male circumcision can help reduce the risk of getting HIV infection.
Diagnoses of HIV in the pathophysiology of HIV
Antibody/antigen tests are the most commonly used tests. They can show positive results typically within 18–45 days after someone initially contracts HIV.
These tests check the blood solely for antibodies. Between 23 and 90 days after transmission, most people will develop detectable HIV antibodies, which can be found in the blood or saliva.
Other antibody tests can be done at home:
- OraQuick HIV Test. An oral swab provides results in as little as 20 minutes.
- Home Access HIV-1 Test System. After the person pricks their finger, they send a blood sample to a licensed laboratory. They can remain anonymous and call for results the next business day.
Nucleic acid test (NAT)
This expensive test isn’t used for general screening, it is for people who have early symptoms of HIV or have a known risk factor. This test looks for the virus itself. It takes from 5 to 21 days for HIV to be detectable in the blood.
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