What is AIDS?

HIV can transmit when body fluids containing the virus come into contact with a permeable barrier in the body or small breaks in moist tissues of areas such as the genitals.

Specifically, HIV can transmit via:

• blood
• semen
• pre-seminal fluid
• vaginal fluids
• rectal fluids
• breast milk

The virus cannot transmit through saliva, so a person cannot contract HIV through open-mouthed kissing, for example.

One of the main causes of HIV transmission in the U.S. is anal or vaginal intercourse. For the transmission to happen, the people must not be using barrier protection, such as a condom, or taking pre-exposure prophylaxis (PrEP), a treatment that aims to prevent HIV transmission among people with known risk factors.

Another main cause of HIV transmission in the country is sharing equipment for injecting drugs.

Less commonly, HIV transmits to babies during pregnancy, childbirth, or breastfeeding.

Also, there is a chance of transmission in blood transfusions, though the risk is extremely low when blood donations are effectively screened.

Undetectable = untransmittable

HIV can only transmit through fluids that contain a certain amount of the virus. If a person has undetectable levels of HIV, the virus cannot transmit to another person.

Some people use a shorthand to refer to the fact that undetectable levels of HIV are untransmittable: U=U.

Doctors consider HIV to be undetectable when the amount of the virus in the body is so low that a blood test cannot identify it.

Having undetectable levels requires a person to continually receive effective treatment and follow the recommended plan carefully, which usually involves taking medications every day.

A person with undetectable levels still has HIV, and regular monitoring with blood tests is key to maintaining this status.

Progression to AIDS

The chances of HIV progressing to AIDS vary widely from person to person and depend on many factors, including the:

• person’s age
• body’s ability to defend against HIV
• accessibility of quality healthcare
• presence of other infections
• person’s genetic resistance to certain strains of HIV
• the strain of HIV, as some are drug-resistant

For the most part, other infections — with bacteria, other viruses, fungi, or parasites — cause the more pronounced symptoms of HIV.

Early symptoms of HIV

Some people with HIV have no symptoms for months or even years after contracting the virus. Partly because of this, 1 in 7 people with HIV in the U.S. does not know that they have it.

While a person with no symptoms may be unlikely to seek care, there is still a high risk of transmission. For this reason, experts recommend regular testing, so that everyone is aware of their HIV status.

Meanwhile, around 80% of people with HIV develop flu-like symptoms around 2–6 weeks after contracting the infection. These symptoms are collectively called an acute retroviral syndrome.

Early symptoms of HIV may include:

• a fever
• chills
• sweating, particularly at night
• enlarged glands or swollen lymph nodes
• a diffuse rash
• fatigue
• weakness
• pain, including joint pain
• muscle aches
• a sore throat
• thrush, or a yeast infection
• unintentional weight loss, with advancing HIV

These symptoms result from the immune system fighting off different types of infection. Anyone who has several of these symptoms and may have contracted HIV in the past 2–6 weeks should take a test.

Some symptoms of HIV vary by sex. Read more about symptoms in males and symptoms in females.

Asymptomatic HIV

After the symptoms of acute retroviral syndrome resolve, many people go on to experience no HIV symptoms for years.

While they feel well and appear healthy, the virus continues to develop and damage the immune system and organs. If the person does not take medication that prevents the replication of the virus, this slow process can continue for around 8–10 years trusted Source.

However, taking antiretrovirals can stop this process and suppress the virus completely.

Late-stage HIV infection

If a person with HIV does not receive effective treatment, the virus weakens the body’s ability to fight infection, exposing it to serious illnesses.

When CD4 cells are severely depleted, at fewer than 200 cells per cubic millimeter, a doctor can diagnose AIDS, which is sometimes called stage 3 HIV.

The presence of certain opportunistic infections, involving bacteria, viruses, fungi, or mycobacteria, also help a doctor identify AIDS.

Symptoms of AIDS can include:

• blurred vision
• a dry cough
• night sweats
• white spots on the tongue or mouth
• shortness of breath, or dyspnea
• swollen glands lasting for weeks
• diarrhea, which is usually persistent or chronic
• a fever of over 100°F (37°C) that lasts for weeks
• continuous fatigue
• unintentional weight loss