HIV is a virus that causes immunodeficiency (the loss of immune function). It progressively kills disease-fighting white blood cells, called CD4 T-cells, leaving the body vulnerable to an ever-widening range of opportunistic infections (OIs). The types of OIs a person can get corresponds to how much the immune system has been destroyed.

The three stages of HIV infection are:

Primary infection Clinical latency Acquired immunodeficiency syndrome (AIDS)

This article describes the possible signs and symptoms of HIV at the different stages of infection. It also explains why different population groups are more likely to experience symptoms of AIDS than others.

Stage 1: Primary Exposure (Acute HIV)

Stage 1 is the phase when HIV enters the body and causes flu-like symptoms as the immune system launches its frontline defense. Also known as acute HIV, primary HIV, acute seroconversion, or acute retroviral syndrome, stage 1 is characterized by the body’s efforts to bring HIV under control.

In fighting the virus, the immune system will release chemicals that trigger whole-body inflammation. This can lead to flu-like symptoms in two of every three cases, usually within two to four weeks of exposure to the virus.

Early symptoms of HIV include:

Fever Chills Headache Sore throat Fatigue Muscle pain Joint pain Night sweats Swollen lymph nodes Mouth ulcers

One in five people may also develop an “HIV rash.” The rash will usually involve raised, reddened areas of skin covered with small, pimple-like bumps. The rash will often affect the upper body and may be accompanied by ulcers in the mouth and on the genitals.

The acute stage can last for around two to four weeks, after which symptoms will spontaneously clear as the body brings the infection under control. The virus is not gone but instead moves into the next phase known as clinical latency.

Stage 2: Clinical Latency (Chronic HIV)

Stage 2 is when the acute HIV symptoms have cleared, but the infection persists “silently” at lower levels. The infection is no longer considered acute (meaning severe and sudden) but is now regarded as chronic (meaning persistent).

Causes for this disparity include stigma, racism, higher rates of poverty, lack of access to quality healthcare, and distrust in public health institutions.

During this prolonged stage, many people do not realize that they’ve been infected and will end up passing the virus to others. There may be certain non-specific signs during this stage, such as swollen lymph nodes (lymphadenopathy), but these also tend to clear within several months.

Even though the infection is largely “silent,” the virus will continue to deplete CD4 T-cells, which normally run between 500 and 1,500 cells per cubic milliliter (cells/mm3) of blood in people without HIV.

During clinical latency, the loss of CD4 T-cells causes immunodeficiency, meaning that the body has lost the immune defenses that normally protect against diseases. The Centers for Disease Control and Prevention (CDC) defines this as a CD4 count between 499 and 200 cells/mm3.

As the CD4 count continues to drop, an ever-widening range of OIs can develop, both common and uncommon.

These include:

Oral thrush Genital herpes HIV-associated diarrhea Bacterial pneumonia Shingles

Even so, people will often fail to connect these conditions to HIV simply because they can occur in the absence of HIV.

HIV Progression

The progression of HIV is not the same for all people. For some, the period of clinical latency may only last for two years. Although there are many reasons for this, including a person’s genetics and the type of HIV they have, social factors like poverty and the lack of insurance also play a part.

Studies have shown that low socioeconomic status is associated with poorer immune status in people with HIV (as measured by the CD4 count). A low CD4 count at the time of exposure is, in turn, associated with faster disease progression.

Stage 3: Symptomatic HIV (AIDS)

Stage 3 is the phase where the immune system has been fully compromised. This leads to serious OIs with a wide range of symptoms.

Also known as AIDS (acquired immune deficiency syndrome), stage 3 is defined by the CDC as having a CD4 count under 200 or the presence of an AIDS-defining condition.

AIDS-defining conditions are those that occur in the setting of HIV that are rarely seen in people with intact immune systems. Some infections, like tuberculosis, can occur at CD4 counts well over 200, but most occur when the CD4 count drops below 200.

On the flip side, it is possible to have a CD4 under 200 and no AIDS-defining condition. Even so, aggressive steps will be taken to prevent them. This includes starting antiretroviral therapy if you haven’t already done so and taking preventive drugs called prophylactics if needed.

Symptoms at this stage are primarily related to the OI a person develops (although some, like AIDS dementia, are the result of long-term harm caused by HIV). Others are only considered AIDS-defining if they recur, are disseminated (dispersed), or are invasive (spread beyond their original site).

There are 27 conditions classified as AIDS-defining by the CDC:

Bacterial infections, multiple or recurrent Candidiasis of bronchi, trachea, or lungs Candidiasis of the esophagus Cervical cancer (invasive) Coccidioidomycosis, disseminated Cryptococcosis, presenting outside of the lung Cryptosporidiosis, chronic intestinal for longer than one month Cytomegalovirus with loss of vision Cytomegalovirus disease (other than in the liver, spleen, or lymph nodes) Encephalopathy, HIV-related (also known as AIDS dementia complex) Herpes simplex virus (HSV), lasting longer than a month or appearing in an area other than the skin Histoplasmosis, disseminated Kaposi’s sarcoma Lymphoid interstitial pneumonia or pulmonary lymphoid hyperplasia complex Burkitt lymphoma Immunoblastic lymphoma Primary lymphoma of the brain Mycobacterium avium complex, disseminated Mycobacterium tuberculosis of any site in or out of the lungs Mycobacterium or similar species, disseminated beyond the lung Pneumocystis pneumonia Pneumonia, recurrent Progressive multifocal leukoencephalopathy (PML) Salmonella septicemia, recurrent Toxoplasmosis of the brain Tuberculosis (TB) Wasting syndrome 

If you suspect that you’ve been exposed to HIV, either now or anytime in the past, see your healthcare provider and ask to be tested.

Because there are treatments today that can help you live a long, healthy life, the CDC recommends HIV testing at least once for everyone ages 13 to 64 as part of routine medical care.

By doing so, you not only protect your long-term health but others around you.

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