HIV and AIDS: Detection, prevention, and treatment

Welcome to Ask the Expert, a UTHealth Houston news series in which leading experts examine pressing health challenges. In this edition, we address National HIV/AIDS and Aging Awareness Day. 

About 1.2 million people in the United States are living with HIV, or human immunodeficiency virus. Because of major advances in medical treatment and technology, people with HIV are living long, healthy lives. 

Here’s what to know about the condition ahead of HIV/AIDS and Aging Awareness Day, observed Sept. 18. 

What is HIV?

HIV is the cause of acquired immunodeficiency syndrome, or AIDS. HIV is a virus that infects and destroys key cells required to resist infections. These key cells are called CD4 cells, and they can spot viruses and bacteria and elicit other cells to attack them. They also help other cells to create specific antibodies against viruses and bacteria.

How is HIV spread?

HIV is not transmitted through normal day-to-day contact, nor through the air, water, food, or public toilet facilities. HIV is spread primarily through unprotected sexual contact with semen or vaginal fluids. 

HIV can also be transmitted by a contaminated blood or blood product transfusion from an HIV-infected donor, by sharing needles or syringes, or in any health clinic where there may be reuse of needles or syringes without adequate sterilization. Any use of needles, such as in tattoo parlors or other body piercing establishments where proper sterile procedures are lax, carries the risk of transmitting HIV.

HIV can also be transmitted from an HIV-infected mother to their child through infected breast milk. 

How is HIV diagnosed?

The virus itself is identified through various routine laboratory tests, such as antibody tests, with saliva or serum. Tests performed in clinical laboratories detect a specific protein component of the virus in the blood, as well as antibodies to the virus. A viral nucleic acid test, known as a PCR test, detects the genome of the virus in blood. PCR tests are particularly useful for tracking the impact of treatment because modern treatment can make PCR tests appear negative. 

Several circumstances should trigger a test for HIV. Clinical signs of weight loss, fevers of uncertain origin, persistent diarrhea (known as “slim disease” in the early part of the epidemic), respiratory infections such as tuberculosis, and other infections that are sometimes unusual, such as fungal and parasitic infections, as well as the occurrence of a sexually transmitted disease or a known exposure to a risk factor, are all warning signs that should prompt HIV testing. 

How can HIV be prevented?

There is no vaccine against this virus. HIV is prevented through safe sexual practices, such as the use of condoms and low-risk sexual practices that avoid any fluid exchange. Treatment of STDs also reduces risk by eliminating open wounds that could facilitate transmission.

There are now also medical and pharmaceutical prevention options, such as daily medications or long-acting shots, that can protect individuals at high risk for infection. 

Prevention of exposure to blood products is paramount: You should never share needles, syringes, or other injecting devices, and you should ensure that any tattoos or body piercings are conducted in sterile conditions. Healthcare workers should also ensure they adhere to universal precautions for handling sharps. 

How is HIV treated? 

HIV is treated through antiretroviral therapy, which is a combination of medications that work by clocking multiple stages of virus replication in the virus life cycle. The major goal of this treatment is to achieve an undetectable level of virus in the blood. 

These medications are available as daily or weekly pills or in long-acting injections. People with HIV should start therapy as soon as possible after diagnosis, whether they are ill or not. Taking the medication regularly is key to preventing mutations and drug resistance. Since the medications can also affect organs, regular checking of liver and renal function is important.

There is also post-exposure medication that can prevent infection when taken within 72 hours of exposure. This medication is administered daily for four weeks. Since HIV can be transmitted from mother to child, pregnant women on HIV treatment have a low risk of transmission to their baby. However, similar medications provided to the infant after birth also prevent transmission.

Why is there no vaccine against HIV?

Traditional vaccines are molecular matches for the actual infection and work by triggering the immune system to produce antibodies and other protective responses to prevent the infection. HIV has two characteristics that defy this process. 

The virus mutates like few other known viruses, meaning it rapidly changes and evades the immune response of antibodies produced against previous viruses. While antibodies are made by the infected person, the virus mutates so fast that those antibodies are no longer effective against the new mutated viruses, creating a kind of virus “whack-a-mole.” One individual can contain more mutated virus variants than all of the influenza variants across the globe—meaning the immune clearance seen with traditional vaccines is not possible. 

Additionally, the virus that causes HIV, which is known as a retrovirus, can make DNA copies of itself and hide in human DNA, making it undetectable by the immune system. From there, it can make viruses that continue to mutate, further avoiding the normal immune clearance that vaccines provide.

What is HIV/AIDS and Aging Awareness Day? 

HIV/AIDS and Aging Awareness Day is a program created by the AIDS Institute to highlight the fact that many people with HIV are now aging and are older adults with different needs and risks of living with HIV. It celebrates the fact that it is possible to live a long and relatively normal life with HIV. But it also demonstrates that more than 50% of those living with HIV in the U.S. are over age 50, and nearly 20% of new infections are occurring in those over age 50. Prevention, testing, and early diagnosis remain paramount to curbing new cases of HIV and AIDs. 

By Joseph McCormick, MD, professor of epidemiology and the James H. Steele, DVM, Professor at UTHealth Houston School of Public Health in Brownsville. All quotes should be attributed to him. 

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