Why Charlie Sheen's HIV is 'undetectable'

Actor Charlie Sheen went on NBC's "Today" show Tuesday to confirm rumors that he was HIV-positive.

The National Enquirer tabloid first reported on Monday that Sheen had contracted the virus and that some of his sexual partners weren't aware. But Sheen maintains that he told all his partners of his HIV status, adding that many threatened to blackmail him for a sum totaling "into the millions."

Sheen does not have AIDS, a condition in which the virus has dramatically suppressed the immune system, leaving the patient susceptible to infections and rare types of cancer.

About 35 million people were living with HIV worldwide as of 2013, according to the World Health Organization, and about 1.5 million people died of AIDS-related illnesses that year. But the virus is no longer a death sentence for those like Sheen, who have access to a cocktail of antiretroviral drugs, The Guardian reported.

His physician Robert Huizenga, an assistant professor of clinical medicine at UCLA, also appeared on the show, and said that Sheen's HIV is now undetectable in his blood.

"Charlie has contracted the HIV virus," Huizenga told "Today" anchor Matt Lauer. "He was immediately put on treatment, strong antiviral drugs which have suppressed the virus - unfortunately, we don't have a cure yet - it suppressed the virus to the point that he is absolutely healthy from that vantage."

The actor has achieved what is known in the medical community as viral suppression by taking a three-drug cocktail known as antiretroviral therapy (ART). This does not mean he is cured, it just means the virus has been reduced to an undetectable level in his body, where it is unable to multiply and wipe out his immune system. Many people who take their medication consistently can achieve viral suppression in three to six months, according to the US Department of Health and Human Services.

A 'hard three letters to absorb'

As of Tuesday, Sheen said he does not know how he contracted the virus. He said he has had unprotected sex with two people since his diagnosis, and his doctor is monitoring both of them.

Sheen said he was diagnosed with HIV four years ago, after suffering from extreme migraines and "sweating the bed." He thought he might have a brain tumor, and was hospitalized. But after numerous tests, doctors confirmed he had HIV. One of the reasons HIV can go long periods before being diagnosed is because its earliest symptoms can mirror those of the flu - many people experience fever, muscle aches, sore throat, and swollen glands. The only way to know for sure if you are HIV positive is to get tested.

"It's a hard three letters to absorb. It's a turning point in one's life," the actor said.

Sheen said he is on a "triple cocktail" of HIV medications and takes four pills a day. He added that since his diagnosis, he has never missed taking his medication.

However, his doctor said there's still a very small chance that Sheen could pass the virus to sexual partners even if he continues his treatment and uses protection.