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HIV Tests
Key takeaways
HIV testing is crucial because a significant percentage of Americans living with HIV are unaware of their condition, leading to delayed treatment and potential transmission to others. The CDC recommends routine screenings as part of standard healthcare.
Various tests, including rapid at-home options and laboratory tests, can diagnose HIV by detecting antibodies or the virus itself. Fourth-generation tests can detect HIV earlier than previous versions.
For individuals diagnosed with HIV, ongoing monitoring through CD4 counts and viral load measurements is essential to track the disease's progression and the effectiveness of treatment and to prevent transmission to others.
Why is HIV testing important?
According to the Centers for Disease Control and Prevention (CDC), roughly 1.2 million Americans lived with HIV by the end of 2019. And about 13 percent of people living with HIV do not know they've contracted the virus.
In addition to not getting the treatment they need, they can unknowingly transmit the virus to others. In fact, almost 40 percent of new HIV cases are transmitted by people who are undiagnosed.
The CDC's recommendations for HIV testing advise healthcare professionals to provide routine screenings for HIV as a part of standard care regardless of any risk factors.
Despite these recommendations, many Americans have never been tested for HIV.
Anyone who hasn't been tested for HIV should consider asking their healthcare professional for a test. They can also seek free and anonymous HIV testing at a nearby clinic.
Visit the CDC's GetTested website to find a local testing site.
Who needs HIV testing?
The CDC advises that routine HIV testing should be provided in all healthcare settings, especially if testing for other sexually transmitted infections (STIs) at the same time.
People engaging in behaviors that put them at an increased risk for contracting HIV should be tested at least once a year.
Known risk factors include:
having multiple sexual partners
engaging in sex without a condom or barrier method and without pre-exposure prophylaxis (PrEP)
having partners with an HIV diagnosis
injecting drugs
HIV testing is also recommended:
before a person begins a new sexual relationship
if a person learns that they're pregnant
if a person has symptoms of another sexually transmitted infection (STI)
An HIV infection is now considered a manageable health condition, especially if treatment is sought early.
If a person contracts HIV, early detection and treatment can help:
improve their frame of mind
lower their risk of disease progression
prevent the development of stage 3 HIV, or AIDS
It can also help reduce their risk of transmitting the virus to other people.
The life expectancy of people with an HIV diagnosis who start treatment early is the same as those without the virus. People who know that they've been exposed to HIV should seek care as soon as possible.
In some cases, if they're treated within 72 hours, their healthcare professional may prescribe post-exposure prophylaxis (PEP). These emergency medications may help reduce their chances of contracting HIV after they've been exposed to it.
What tests are used to diagnose HIV?
A number of different tests can be used to check for HIV. These tests can be performed on blood samples or saliva samples. Blood samples can be obtained via an in-office finger prick or a blood draw in a laboratory.
Not all tests require a blood sample or a visit to a clinic.
In 2012, the Food and Drug Administration (FDA) approved the OraQuick In-Home HIV Test. It's the first rapid test for HIV that can be performed at home using a sample from a swab inside your mouth.
If a person thinks they've contracted HIV, it can take anywhere from 1 to 6 months after transmission for a standard HIV test to produce positive results.
These standard tests detect antibodies to HIV rather than the virus itself. An antibody is a type of protein that fights off pathogens.
According to Avert, third-generation HIV tests — which are ELISA tests — can only detect HIV 3 months after exposure to the virus.
This is because it generally takes 3 months for the body to produce a detectable number of antibodies.
Fourth-generation HIV tests, which look for antibodies and the antigen p24, can detect HIV 18 to 45 days after transmission. Antigens are substances that cause an immune response in the body.
According to the Centers for Disease Control and Prevention, 97 percent of people with HIV produce a detectable number of antibodies within 3 months. Although it may take 6 months for some to produce a detectable amount, this is rare.
If a person thinks they've been exposed to HIV, they should tell their healthcare professional. A viral load test that directly measures the virus can be used to detect whether someone has recently acquired HIV.
What tests are used to monitor HIV?
If a person has received an HIV diagnosis, it's important for them to monitor their condition on an ongoing basis.
Their healthcare professional can use several tests to do this. The two most common measures for assessing HIV transmission are CD4 count and viral load.
CD4 count
HIV targets and destroys CD4 cells. These are a type of white blood cell found in the body. Without treatment, the CD4 count will decrease over time as the virus attacks the CD4 cells.
If a person's CD4 count decreases to fewer than 200 cells per cubic millimeter of blood, they'll receive a diagnosis of stage 3 HIV, or AIDS.
Early and effective treatment can help a person maintain a healthy CD4 count and prevent the development of stage 3 HIV.
If treatment is working, the CD4 count should remain level or increase. This count is also a good indicator of overall immune function.
If a person's CD4 count drops below particular levels, their risk of developing certain diseases increases substantially.
Based on their CD4 count, their doctor may recommend prophylactic antibiotics to help prevent these infections.
Viral load
Viral load is a measure of the amount of HIV in the blood. A healthcare professional can measure the viral load to monitor the effectiveness of HIV treatment and the status of the disease.
When a person's viral load is low or undetectable, they're less likely to develop stage 3 HIV or experience its associated immune dysfunction.
A person is also less likely to transmit HIV to others when their viral load is undetectable.
People with undetectable viral loads should still continue to use condoms and other barrier methods during sexual activity to prevent transmission to others.
Drug resistance
A healthcare professional may also order tests to learn if a strain of HIV is resistant to any medications used in treatment. This can help them decide which anti-HIV drug regimen is most appropriate.
Other tests
A medical professional may also use other tests to monitor someone for common complications of HIV or side effects of treatment. For example, they may order regular tests to:
monitor liver function
monitor kidney function
check for cardiovascular and metabolic changes
They may also perform physical exams and tests to check for other illnesses or infections associated with HIV, such as:
A CD4 count below 200 cells per cubic millimeters isn't the only sign that HIV has progressed to stage 3 HIV. Stage 3 HIV can also be defined by the presence of certain opportunistic illnesses or infections, including:
fungal diseases, such as coccidioidomycosis or cryptococcosis
candidiasis, or yeast infection, in the lungs, mouth, or esophagus
histoplasmosis, a type of lung infection
Pneumocystis jiroveci pneumonia, which was previously known as Pneumocystis carinii pneumonia
recurrent pneumonia
tuberculosis
mycobacterium avium complex, a bacterial infection
chronic herpes simplex ulcers, lasting longer than one month
isosporiasis and cryptosporidiosis, intestinal diseases
recurrent salmonella bacteremia
toxoplasmosis, a parasitic infection of the brain
progressive multifocal leukoencephalopathy (PML), a brain disease
invasive cervical cancer
Kaposi sarcoma (KS)
lymphoma
wasting syndrome, or extreme weight loss
Continuing HIV research
As testing advances, researchers are hoping to find pathways to a vaccine or a cure in the coming years.
As of 2020, there are over 40 approved antiretroviral drugs on the market with new formulations and methods being researched all the time.
Current testing only detects markers of the virus as opposed to the virus itself, but research is finding ways the virus can hide in immune system cells. This discovery is allowing for better understanding and more insight into an eventual vaccine.
The virus mutates rapidly, which is one of the reasons it's a challenge to suppress. Experimental therapies such as a bone marrow transplant to treat lymphoma using stem cells are being tested for treatment potential.
