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Investigating Hepatitis C
Any disease investigation requires a bit of detective work. There are lots of pieces to the puzzle. Sometimes we have all the information we need; sometimes we need more. For hepatitis C, the piece of information that kicks off an investigation is a positive lab test.
How we test for hepatitis C
When we think someone has hepatitis C, we require two types of blood tests. The first is usually an antibody test, which measures parts of the blood that fight off viruses, bacteria, and other toxins. The body makes these when a person gets an infection like hepatitis C.
If the antibody test is positive, we know the person had exposure to the hepatitis C virus at some point in their life. Once someone has a positive hepatitis C antibody test, the antibody test results will always be positive even after the infection clears up. About 15%-25% of people will fight off the virus without treatment.
For that reason, the person needs a second blood test which looks specifically for hepatitis C virus. If this viral test is negative, the person does not have hepatitis C infection and cannot spread the disease to anyone else. If their viral test is positive, the person has hepatitis C and can spread it to other people.
Searching for the source of the infection
In our investigation, we try to figure out how long the person might have been infected. We’re most interested in newly acquired hepatitis C infections. These are the cases that will usually tell us if there is an outbreak of the disease or a new trend that we need to be concerned about.
We try to investigate new cases and find out how they were exposed. People typically get infected by sharing needles or equipment used for taking drugs. Most of our newly acquired cases are through drug use associated with the opioid epidemic. We also ask a lot of general questions, especially if someone tells us they are not using drugs.
Then we ask about other types of risk factors or potential places they could have been exposed to the virus. This requires a lot of skill and sensitivity on the part of our staff. We are asking someone we just met some very personal questions.
If we think someone was infected with hepatitis C through a medical procedure, then a viral test near the time of infection becomes very important. Outbreaks in healthcare settings are especially concerning for patient safety. Special tests at the Centers for Disease Control and Prevention can do a genetic fingerprint of the virus. People infected by the same person or at the same time will have the same viral strain.
No one test will tell us if someone has a brand new hepatitis C infection. We look at the results of multiple types of tests—much like clues in a detective case—as well as specific symptoms the person may have had at the time of the tests. We also look for negative hepatitis C test results the person may have had in the past. The goal of this work is to determine when the person got infected.
For people with hepatitis C infection, we make sure they connect with their healthcare providers to start treatment. In almost all cases, people are cured. Learn more about hepatitis C, the risk factors, and how to get tested.