Since its discovery in the early 1980s, some 35 million people worldwide have died from causes related HIV (more on that later) or its more progressed form, AIDS. It's had a devastating effect on gay communities, on groups of free-loving artists (remember Rent?), and on entire African nations. And even though about a million died from HIV-related causes in 2016, scientific advances have turned HIV from a death sentence into a livable chronic condition. An estimated 1.2 million Americans, and about 37 million worldwide, are living with HIV.
But the virus is far from conquered. Here's what you need to know about HIV and AIDS.
How is HIV spread?
You might remember this part from middle school health class: HIV can spread through unprotected sex, by sharing needles, or coming into contact with contaminated blood, or from mother to child either during pregnancy or via breast milk.
But your health teacher likely didn't tell you is that it's actually pretty hard to transmit HIV, even sexually. For people receiving anal sex, only one in every 71 exposures causes infection, according to estimates from one 2012 study. It's even lower for tops ("insertive anal") and everyone involved in vaginal sex. That doesn't mean you can't get HIV from having sex with an infected partner after you've been super careful your whole life. It just means it's not a given that you will get it. Also, more evidence is showing that those who are living with it can lead healthy sex lives without passing it on to others.
Having other STDs might also make a person more likely to become infected with HIV. That's because, as the CDC notes, "the same behaviors and circumstances that may put you at risk for getting an STD can also put you at greater risk for getting HIV." Also having open sores from other STDs can give HIV another way in.
Who gets it?
HIV isn't picky—anyone can get it. In the US, populations with the highest infection rates include men who have sex with men, intravenous drug users, African Americans, teens and young adults, and people in the south. One specific subsection most affected are black men who sleep with men—recent research shows that about one out of every two will contract HIV at some point in their lives. Around 40 percent of people worldwide with HIV, and one in eight Americans, don't know they have it, which can make them more likely to unwittingly transmit it to someone else.
What does HIV do to your body?
If HIV weren't so scary, we'd call it kind of a genius because of how craftily it operates. Once it's in the body, the virus infiltrates a particular kind of white blood cell (or T cell) called CD4, which plays a key role in the body's immune response. The virus takes over the machinery of the cell so that it generates more versions of itself, which attack more CD4 cells.
There are three stages of HIV infection. The first, which clinicians call acute retroviral syndrome, can cause flu-like symptoms in some patients. This happens just a few weeks after the initial infection and it's the stage at which transmission is more likely because an HIV test won't come up positive until three months after the initial infection. That's how long it takes the body to make enough antibodies for the test to read.
In the second stage, the virus keeps reproducing, but the person doesn't experience any symptoms. AIDS is the third, most advanced stage. By that point the virus has obliterated the body's immune system, leaving room for opportunistic infections. People almost never die of AIDS itself—instead, they die of pneumonia, or rare cancers, things that people only get when their immune systems aren't working properly.
Is HIV curable?
For now, no. Despite decades of research, we still do not have a cure or vaccine. That's in part because HIV mutates so quickly that scientists can't keep up with it. There were a few promising glimpses over the years—babies and grown men who appeared to be cured—but the virus always came back. The damn thing has stayed at least one step ahead, at least so far.
But there's treatment. It's a combination of drugs called antiretroviral therapy (ARVs or ARTs) that stop HIV from binding to CD4 cells or from replicating inside it. People on ARVs take the drugs every day for their entire lives, which isn't ideal, but it's definitely worth it to keep the virus at bay.
And there are preventative steps, too. If a pregnant woman knows she is HIV-positive, she can take medications to make sure her baby doesn't get it. People having sex with people who have HIV (or might, if you're playing the field) can use condoms or take a relatively new preventative drug called PrEP.
Should I get tested?
It depends. The CDC recommends that most people get tested at some point in their lives, but people with certain risk factors—more than one sexual partner, having sex with someone you know has HIV (or someone whose sexual history you don't know), sharing needles, or just a man who has sex with men—you should get tested at least once a year, or even more often (like every three to six months). So if you're in a monogamous heterosexual relationship, you're probably good. If not, toss it in with the other tests you get during your annual checkup.