HIV: what is viral load and why adherence to treatment interrupts transmission

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HIV stands for “human immunodeficiency virus”. Biologically, HIV belongs to the category of retroviruses, being classified into a subfamily called Lentiviridae. Viruses of this type have a prolonged incubation period before the onset of symptoms, can infect blood cells and nervous system, and attack the immune system.

Aids (Acquired Immunodeficiency Syndrome) is the severe form of HIV infection. However, not all HIV-infected people develop AIDS, and treatment is essential to prevent this from happening.

what happens during the infection

Viruses are simple microscopic structures, smaller in size than other parasites such as fungi and bacteria. They necessarily need a living cell to survive and multiply.

When a virus invades the organism, it adheres to human cells in order to install itself and produce numerous copies of itself. This process happens over and over again, starting the infection.

In the first phase, called acute infection, the HIV incubation takes place, which is the period between exposure to the virus and the appearance of the first signs of the disease. Incubation can range from three to six weeks. The first antibodies against the virus are produced by the body within 30 to 60 days.

During HIV infection, the numerous copies of the virus primarily target defense cells called T-CD4+ lymphocytes, commonly known as white blood cells. These immune system cells are responsible for identifying, memorizing and destroying invading agents, which can be viruses, bacteria, among other microorganisms.

What is viral load and how treatment works

Viral load is a amount of virus present in the patient’s blood – that is, the more copies the virus produces, the higher the viral load in the body.

HIV treatment is carried out through the use of antiretroviral drugs, which prevent the process of viral replication in the human body. By blocking the production of new copies of the virus, the drugs work to reduce the viral load in the blood.

The Ministry of Health recommends that the viral load test is performed every six months, for monitoring infection and adherence to treatment. The goal of treatment is to reduce the viral load to levels undetectable by clinical examinations, to avoid a weakening of the immune system.

Indetectável = Intransmissível (I = I)

People living with HIV undergoing treatment and with an undetectable viral load for at least six months do not transmit the virus sexually. The term Undetectable = Non-transmissible (I = I) is adopted by scientists and leading institutions on HIV worldwide.

Among the references of the concept are three large studies on the sexual transmission of HIV among thousands of serodifferent couples, a situation in which one partner lives with HIV and the other does not.

In surveys, carried out between 2007 and 2016, cases of sexual transmission of HIV from a person living with HIV with suppressed viral load to a partner with negative serology were not detected.

The studies have been published in the world’s leading scientific journals, including the Lancet magazine, the New England Journal of Medicine (NEJM) and the Journal of the American Medical Association (JAMA).

“In these studies, it was found that when the HIV-infected partner had a viral load below the detection limit of the test, which is normally 40 copies of the virus per ml of blood, that is, a very low amount of virus, there was no streaming. Therefore, the concept of undetectable is equal to non-transmissible was established”, explains researcher Sylvia Teixeira, a virologist at the Oswaldo Cruz Institute (IOC/Fiocruz), in Rio de Janeiro.

In Brazil, the concept is described in an information note from the Ministry of Health published in 2019. In the document, the folder reinforces that knowledge about the transmissibility of HIV helps to reduce the stigma of the disease.

“A correct understanding of transmissibility/non-transmissibility has positive effects on stigma and self-stigma, sexual and reproductive rights, testing, linking to health services and adherence to treatment”, says the ministry.

In December 2018, the Ministry of Health launched the “Undetectable” campaign, which brings together a series of testimonies from people of different ages who report what it is like to live with the virus and the viral load at undetectable levels.

Advances in technologies against HIV

The first antiretroviral drugs appeared in the 1980s. In March 1987, the Food and Drug Administration (FDA), a body similar to the National Health Surveillance Agency (Anvisa) in Brazil, approved the first drug for the treatment of AIDS, the Zidovudine (also called azidothymidine or AZT).

The first drugs had strong side effects, which made adherence to treatment difficult.

With the advancement of technology in areas such as medicine, virology and pharmacology, in addition to reducing the viral load and preserving the functions of the immune system, the regular use of medicines helps to improve the quality of life of people living with HIV.

With the proper functioning of the body’s defenses, the risks of hospitalizations and opportunistic infections are also reduced.

Antiretrovirals have been distributed in Brazil by the Unified Health System (SUS) since 1996. There are at least 22 drugs, in 38 different pharmaceutical presentations, according to the Ministry of Health.

Anvisa has approved a new drug for the treatment of HIV that combines two different substances in a single pill. The new drug combines lamivudine and sodium dolutegravir, which are currently used as separate remedies in the antiretroviral treatment regimen.

The ministry recommends starting treatment soon after HIV diagnosis. Tests can be taken free of charge at Testing and Counseling Centers (know where to take the test).

Reference: CNN Brasil

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