Risk of HIV transmission highest early in infection

March 5, 2007

New evidence suggests that the risk of HIV transmission may be highest in the early stages of infection. According to a study published in the April 1 issue of The Journal of Infectious Diseases, now available online, early infection accounted for nearly half of all transmission occurrences in an HIV-infected population in the province of Quebec, Canada.

Bluma Brenner, PhD, and Mark Wainberg, PhD, of the McGill AIDS Centre in Montreal, and colleagues from several hospitals and health clinics in Canada studied HIV transmission through phylogenetic analysis—essentially, drawing the virus’s family tree. The technique follows the history of a virus as it spreads from one person to another by looking at the evolution of viral genetic material in infected individuals.

Drs. Brenner, Wainberg, and colleagues found that 49 percent of early infections formed phylogenetic clusters—very close branches on the family tree. This indicated that a large portion of HIV acquisition could be attributed to individuals transmitting the virus who were themselves in the early stages of infection, before the virus had had time to mutate much. Therefore, early infection—also known as primary infection—which represented “less than 10 percent of the total samples, disproportionately accounted for about half of subsequent transmission events.”

A high viral load associated with early HIV infection is what makes newly infected individuals so infectious, according to Drs. Brenner and Wainberg. In an editorial accompanying the article, authors Deenan Pillay, MD, of the Health Protection Agency and University College London, and Martin Fisher, MD, of the Brighton and Sussex University Hospitals, pointed out that diagnosis of HIV reduces the risk of transmission. But, they note, symptoms of primary HIV infection are non-specific. Only a small proportion of infected individuals are diagnosed in early infection, thus compounding the difficulties in preventing transmission at that stage of infection.

“The early infection stage can be entirely asymptomatic,” Dr. Wainberg added. “This is why people who are recently infected may not know it, and will probably often test negative by conventional antibody screening. Hence, we must do a much better job of identifying recently infected people if we are to be able to counsel them to modify high-risk sexual behavior and desist from transmitting the virus.”

He suggested the development of affordable tests such as polymerase chain reaction assays to directly monitor the presence of the virus, instead of relying on the current method of antibody screening.

In addition, Dr. Pillay and Fisher asserted that more innovative and effective prevention strategies are needed to stem HIV transmission during primary infection and block the spread of drug-resistant viruses.

Source: Infectious Diseases Society of America

Explore further: Large increases in HIV suppression needed to reduce new infections in critical population

Related Stories

Children who keep HIV in check

October 5, 2016

Some HIV-infected - and untreated - children do not develop AIDS. A new study shows that they control the virus in a different way from the few infected adults who remain disease-free, and sheds light on the reasons for this ...

The microbial superhero in your vagina

October 11, 2016

The aisle is marked with a little red sign that says "Feminine Treatments". Squeezed between the urinary incontinence pads and treatments for yeast infections, there is a wall of bottles and packages in every pastel shade ...

Recommended for you

Researchers use CRISPR to accelerate search for HIV cure

October 25, 2016

Researchers at UC San Francisco and the academically affiliated Gladstone Institutes have used a newly developed gene-editing system to find gene mutations that make human immune cells resistant to HIV infection.

Study unlocks secret of common HIV strain

October 13, 2016

A discovery that the most common variant of the HIV virus is also the "wimpiest" will help doctors better treat millions of individuals around the world suffering from the deadly disease, according to one of the world's leading ...

Children could point the way to new HIV treatments

September 29, 2016

Children with HIV who can resist the disease progressing could point the way to new treatments for HIV infection that are more widely applicable to infected adults and children alike, an international team of researchers ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.