Many people who have HIV also have been exposed to other infections, such as hepatitis C. Over half of people who become HIV infected through injecting drugs also become infected with hepatitis C. Overall, more than one third of all Americans infected with HIV have hepatitis C, too. So HIV-hepatitis C coinfection is common.
Having both viruses also makes it a little harder to deal with either one. There are specific medical issues that are unique to coinfected patients.