2. Acquired immunodeficiency syndrome (AIDS) is a chronic, potentially life-threatening condition caused by the
human immunodeficiency virus (HIV). By damaging your immune system, HIV interferes with your body's ability to
fight infection and disease. HIV is a sexually transmitted infection (STI). It can also be spread by contact with
infected blood or from mother to child during pregnancy, childbirth or breast-feeding. The human body can’t get
rid of HIV and no effective HIV cure exists. So, once you have HIV, you have it for life.However, by taking HIV
medicine (called antiretroviral therapy or ART), people with HIV can live long and healthy lives and prevent
transmitting HIV to their sexual partners. In addition, there are effective methods to prevent getting HIV through
sex or drug use, including pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP).First identified in
1981, HIV is the cause of one of humanity’s deadliestand most persistent epidemics.
What is AIDS ?
AIDS is the late stage of HIV infection that occurs when the body’s immune system is badly damaged
because of the virus.
In the U.S., most people with HIV do not develop AIDS because taking HIV medicine every day as
prescribed stops the progression of the disease.
A person with HIV is considered to have progressed to AIDS when:
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
• they develop one or more opportunistic infections regardless of their CD4 count.
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.
Causative agent of AIDS
The causative agent of aids is “Human Immunodefficiency Virus (HIV)” . HIV (human immunodeficiency virus) is a virus
thatattacks thebody’s immunesystem.HIVinfectionin humanscamefroma typeof chimpanzeein Central Africa.
The chimpanzee version of the virus (called simian immunodeficiency virus,or SIV) was probably passed to humans
when humans hunted these chimpanzees for meat and came in contact with their infected blood.
Studies showthat HIV may have jumped from chimpanzees to humans as far back as the late 1800s.
Over decades, HIV slowly spread acrossAfrica and later into other parts of the world. We know that the virus has
existed in the United States sinceat leastthe mid to late1970s.
What are the stages of HIV?
3. When people with HIV don’t get treatment, they typically progress through three stages. But HIV medicine can slow or prevent
progression of the disease. With the advancements in treatment, progression to Stage 3 is less common today than in the early
days of HIV.
Stage 1: Acute HIV Infection
People have a largeamount of HIV in their blood.They are very contagious.
Some people have flu-likesymptoms. This is the body’s natural responseto infection.
But some people may not feel sick rightaway or at all.
If you have flu-likesymptoms and think you may have been exposed to HIV, seek medical careand ask for a test
to diagnoseacuteinfection.
Only antigen/antibody tests or nucleic acid tests (NATs) can diagnoseacute infection.
Stage 2: Chronic HIV Infection
This stage is also called asymptomatic HIVinfection or clinical latency.
HIV is still activebutreproduces at very low levels.
People may not have any symptoms or get sick duringthis phase.
Without takingHIV medicine, this period may lasta decade or longer, but some may progress faster.
People can transmitHIV in this phase.
At the end of this phase, the amount of HIV in the blood (called viral load) goes up and the CD4 cell countgoes down. The
person may have symptoms as the virus levels increasein the body, and the person moves into Stage 3.
People who take HIV medicineas prescribed may never move into Stage 3.
Stage 3: Acquired Immunodeficiency Syndrome (AIDS)
The most severe phase of HIV infection.
People with AIDS have such badly damaged immune systems that they get an increasingnumber of severe illnesses,
called opportunistic infections.
People receive an AIDS diagnosis when their CD4 cell countdrops below 200 cells/mm,or if they develop
certain opportunistic infections.
People with AIDS can have a high viral load and be very infectious.
Without treatment, people with AIDS typically surviveaboutthree years.
4. Symptoms of AIDS
Primary infection (Acute HIV)
Some people infected by HIV develop a flu-like illness within two to four weeks after the virus enters the body. This
illness, known as primary (acute) HIV infection, may last for a few weeks. Possible signs and symptoms include:
Fever
Headache
Muscle aches and joint pain
Rash
Sore throat and painful mouth sores
Swollen lymph glands, mainly on the neck
Diarrhea
Weight loss
Cough
5. Night sweats
These symptoms can be so mild thatyou mightnoteven notice them.However, the amountof virus in your bloodstream (viral lo ad) is
quite high at this time.As a result, the infection spreads more easilyduring primaryinfection than during the next stage.
Clinical latent infection (Chronic HIV)
In this stage of infection, HIV is still present in the body and in white blood cells. However, many people may not have
any symptoms or infections during this time.
This stage can last for many years if you're not receiving antiretroviral therapy (ART). Some people develop more
severe disease much sooner.
Symptomatic HIV infection
As the virus continues to multiply and destroy your immune cells — the cells in your body that help fight off germs — you
may develop mild infections or chronic signs and symptoms such as:
Fever
Fatigue
Swollen lymph nodes — often one of the first signs of HIV infection
Diarrhea
Weight loss
Oral yeast infection (thrush)
Shingles (herpes zoster)
Pneumonia
Progression to AIDS
Thanks to better antiviral treatments, most people with HIV in the U.S. today don't develop AIDS. Untreated, HIV typically
turns into AIDS in about 8 to 10 years.
When AIDS occurs, your immune system has been severely damaged. You'll be more likely to develop opportunistic
infections or opportunistic cancers — diseases that wouldn't usually cause illness in a person with a healthy immune system.
The signs and symptoms of some of these infections may include:
Sweats
6. Chills
Recurring fever
Chronic diarrhea
Swollen lymph glands
Persistent white spots or unusual lesions on your tongue or in your mouth
Persistent, unexplained fatigue
Weakness
Weight loss
Skin rashes or bumps
7. How Is HIV/AIDS Transmitted?
Sexual contact - HIV is spread most commonly by sexual contact with an infected partner. The virus
enters the body through the lining of the vagina, vulva, penis, rectum, or mouth during sexual activity.
Blood contamination - HIV may also be spread through contact with infected blood. However, due to the
screening of blood for evidence of HIV infection, the risk of acquiring HIV from blood transfusions is
extremely low.
Needles - HIV is frequently spread by sharing needles, syringes, or drug use equipment with someone
who is infected with the virus. Transmission from patient to healthcare worker, or vice-versa through
accidental sticks with contaminated needles or other medical instruments, is rare.
Mother-infant - HIV also can be spread to babies born to, or breastfed by, mothers infected with the virus.
Structure of HIV
Human immunodeficiency virus is a virus with icosahedral capsid symmetry and is an enveloped virus . the
envelope contains HIV glycoprotein spike structures which help the virus to get attatched to the host cell .
In a mature, infectious HIV virion, the viral genome is housed within a conical capsid core comprised of the
viral capsid (CA) protein. HIV is called a retrovirus because it works in a back-to-front way. Unlike other
viruses, retroviruses store their genetic information using RNA instead of DNA, meaning they need to 'make'
DNA when they enter a human cell in order to make new copies of themselves.
8. Pre-Exposure Prophylaxis (PrEP)
Pre-exposure prophylaxis (or PrEP) is a way for people who do not have HIV but who are at very high risk of getting HIV to preven t
HIV infection by taking a pill every day. The pill (brand name Truvada) contains two medicines (tenofovir and emtri citabine) that are
used in combination with other medicines to treat HIV. When someone is exposed to HIV through sex or injection drug use, thes e
medicines can work to keep the virus from establishing a permanent infection. When taken daily, PrEP is highly effective for
preventing HIV. Studies have shown that PrEP reduces the risk of getting HIV from sex by about 99% when taken daily. Among
people who inject drugs, PrEP reduces the risk of getting HIV by at least 74% when taken daily. PrEP is much less effective if it is not
taken consistently.
Post-exposure prophylaxis
PEP, or post-exposure prophylaxis, is a short course of HIV medicines taken very soon after a possible
exposure to HIV to prevent the virus from taking hold in your body.You must start it within 72 hours after
you were exposed to HIV, or it won’t work. Every hour counts.PEP should be used only in emergency
situations. It is not meant for regular use by people who may be exposed to HIV frequently. PEP is effective in
preventing HIV infection when it’s taken correctly, but it’s not 100% effective. The sooner you start PEP after a
possible HIV exposure, the better. While taking PEP, it’s important to keep using other HIV prevention
methods, such as using condoms the right way every time you have sex and using only new, sterile needles
and works when injecting drugs. The HIV medicines used for PEP may cause side effects in some people.
These side effects can be treated and aren’t life-threatening.If you are taking PEP, talk to your health care
provider if you have any side effect that bothers you or that does not go away.PEP medicines may also
interact with other medicines that a person is taking (called a drug interaction). For this reason, it’s important
to tell your health care provider about any other medicines that you are taking on regular basis.
Reference
A text book of microbiology by anantnarayn and paniker
www.google.com
https://stanfordhealthcare.org
https://www.cdc.gov/hiv/basics/whatishiv.html
