Last Updated on June 4, 2020 by Shuvani Sanyal, MD
HIV and the hepatitis C virus (HCV) share many of the same characteristics, but there are also some very distinct differences in the way they are transmitted, how long each virus lives outside of the body, disease progression, and treatment. This post explores some of the similarities and differences between HIV and HCV.
Both HIV and hepatitis C are RNA viruses, but they are different types of RNA viruses – HIV is a retrovirus and HCV is a flavivirus.
HIV mainly infects human immune cells (CD4, macrophages, and dendritic cells). HCV mainly infects liver cells.
HIV goes through a complex process where the virus inserts its generic material into the host DNA cell and uses the host genetic material to replicate. HCV, on the other hand, uses the host’s cell to replicate, but does not insert itself into the host DNA. Those differences have major implications when discussing HIV and HCV treatment and disease progression – especially when co-infected.
In regard to how much each virus replicates on a daily basis – HIV replicates billions of new viruses vs. the trillions that HCV replicates daily.
Although HIV has a high mutation rate, HCV is thought to replicate and mutate at a much higher rate than HIV.
Studies are underway to find a vaccine for HIV and HCV, but because of the high mutation rate of both viruses, it will likely take quite some time for a vaccine that will prevent HIV or HCV infection to be available for use.
In the United States, it is estimated that more than 4 million Americans are infected with chronic HCV compared to about 1.2 million who are estimated to be infected with HIV. Worldwide, the estimates are in the range of 40 million people infected with HIV compared to 170 million infected with HCV.
There are different strains of HIV (HIV1 and HIV2) and HCV (genotypes 1, 2, 3, 4, 5 & 6). In the United States, HIV1 is the most common strain of HIV and genotype 1 is the most common strain of HCV.
HIV and hepatitis C are transmitted in similar ways – through blood routes, although there are clear differences in the risk of transmission. The hepatitis C virus is about 10 times more concentrated in blood than HIV. This means that the hepatitis C virus can be transmitted easier when any HCV-infected blood is involved.
In the United States, one of the most common ways HIV is transmitted is through anal and vaginal sex. HIV can also be transmitted by sharing infected needles and an HIV positive mother can pass HIV to her child.
The most common way hepatitis C is transmitted is from sharing HCV-infected needles and drug preparation and using tools. Transmission routes of hepatitis C that are less common but still possible are sexual and from mother to child.
HIV & HCV Outside the Body
Once HIV is exposed to air, it lasts only a few moments, but may live longer if blood is present – especially in a closed environment, like a syringe. Hepatitis C, on the other hand, has been found to live outside the body for at least 16 hours but not longer than 4 days, and in a syringe for up to 2 months. This is the reason why, for instance, exposure to blood through unsafe tattooing carries a risk of transmission of hepatitis C, but it generally does not carry a risk of HIV transmission.
In people with HIV, the viral load affects transmission and disease progression. A high viral load for someone with HIV is in the range of 5,000 to 10,000 copies/mL. In contrast, a high HCV viral load for people with hepatitis C is any amount higher than 800,000. Frequently, people with HCV have viral load amounts in the millions. Studies have not found that a high hepatitis C viral load increases transmission of hepatitis C or disease progression. However, there is some evidence that a high HCV viral load increases the chances of transmission of HCV from mother to child.
Chronic HIV vs. Hepatitis C Infection
All people who are initially infected with HIV will have a long-term or chronic infection. HCV is different – some people (about 20-40%) who are initially infected (acute) will naturally resolve or clear an HCV infection. The other 60-80% will have a long-term chronic infection.
HCV can be cured in those who naturally clear the infection, and the viral load can be reduced to produce a sustained virological response in those with the chronic form – this is because HCV does not integrate into the host’s DNA when it is replicating. It’s a different story with HIV, because HIV inserts itself into the host’s DNA. As a result, HIV treatment is aimed at lowering HIV viral load, increasing or stabilizing CD4 cell counts and preventing long-term consequences of infection – similar to treatment for chronic HCV.
The medications used to treat HIV can lead to drug resistance, because they are direct antiviral medications. The newly approved protease inhibitors used in combination with pegylated interferon and ribavirin for people infected with chronic HCV genotype 1 can also lead to drug resistance.
People infected with HCV genotypes 2 or 3 are only prescribed pegylated interferon and ribavirin – those two medications do not lead to drug resistance alone.
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Are you undergoing treatment for HIV or HCV? What has been your experience with treatment or reducing virus replication? Did this article answer some of your questions about HIV or HCV? Share your thoughts in the comments section below!