In the crisis days of AIDS, opportunistic infections posed the greatest threat to HIV-positive people. Today, potent HIV regimens can deliver undetectable viral loads and robust CD4 counts, dramatically extending life spans of those with access to treatment. Success, however, has opened the door for another viral scourge.

Enter liver disease, a leading killer of people with HIV. It usually results from the hepatitis C virus (HCV), which infects about 30 percent of HIV-positive people in the United States. That’s at least 300,000 Americans facing a potentially deadly viral assault on livers already stressed by the toll of HIV, the toxicity of HIV meds and, for some people, the damages of drug and alcohol abuse.

Similar to the way HIV co-opts CD4 cells in the body’s immune system, HCV infects and multiplies in the cells of the liver, the body’s detoxifyer. As the immune system attacks the infection, inflammation results, which can damage the liver. (“Hepatitis” means “inflammation of the liver.”) The consequence is often scar tissue, known as fibrosis in its milder form and cirrhosis when it is more advanced. A needle biopsy performed by a doctor detects the degree of damage. Roughly 20 percent to 30 percent of people living with hep C develop cirrhosis, putting them at risk for compromised liver function and, ultimately, liver failure or cancer.

To complicate matters, HCV often exhibits no symptoms for decades, even while it can slowly erode liver health. And so, like HIV, hepatitis C often goes undetected, potentially wasting valuable time when treatment could cure hep C and prevent critical liver damage.

Unlike hepatitis A and B, there is no vaccine for HCV.

Because HIV and HCV are both blood-borne infections, many people with HIV also have hep C. Sharing needles and drug works is by far the main route of HCV transmission. While semen does not seem effective at transmitting HCV, there are cases of sexual transmission, particularly among HIV-positive gay men. (Click here to read “Let’s Talk About Sex.”) In general, people with HIV are more vulnerable to HCV.

In other words, having HIV itself is a risk factor for HCV.

Guidelines recommend that all HIV-positive people undergo HCV testing and regular liver function screening. Abnormal liver enzymes can be a sign of acute HCV infection. (Most HIV docs follow these guides, for once giving people with HIV an advantage; HIV-negative people might not get such screenings.) Early detection is crucial because treating HCV in the first six months can triple the likelihood of a cure, and it can cut treatment to just 24 weeks, half the usual time.

Compared with people mono-infected with HCV, those coinfected with HIV face steep challenges.

“These diseases have a negative effect on each other,” says Laveeza Bhatti, MD, director of the Hepatitis C/HIV Co-infection Clinic at the AIDS Healthcare Foundation in Los Angeles. “It’s kind of like adding fuel to the fire.”

Coinfected people can experience more rapid liver disease progression, developing cirrhosis at a rate double that of people with HCV alone. Though many people living with both viruses remain stable for years, up to 30 percent may progress rapidly, with their livers worsening significantly over the course of a few years, not the usual decades. This may be partly because the liver processes many HIV meds, risking liver toxicity. Studies suggest, too, that HIV itself hastens liver damage, though some meds may be more toxic than others so be sure to discuss with your doc.

The good news, says Daniel Fierer, MD, of The Mount Sinai Hospital in New York City, is that suppressing your HIV viral load with HIV meds may slow HCV’s liver damage. 

Though hepatitis C can be cured with the standard drug combination of pegylated interferon plus ribavirin, cures are less common for coinfected people. On the (big) plus side, the FDA recently approved two HCV protease inhibitors that are expected to improve cure rates—a cure is known as a sustained viral response (SVR)— for people coinfected with genotype 1 hep C and HIV. (Click here to read “Time for Treatment?”) Also encouraging: Many more new HCV drugs are in the pipeline.

Another promising therapy? Awareness. What you don’t know can hurt you, but knowledge is good medicine.

For more information, visit hepmag.com/hivcoinfection.