"We've still got a long way to go" Australia may be on track to eliminate hepatitis C, but more work needs to be done.
Hepatitis C is the inflammation of the liver caused by the hepatitis C virus (HCV) - an enveloped, positive-sense single-stranded RNA virus. The infection is often acute, however around 1 in 20 people affected will develop a chronic infection. The infection is considered cured when a patient’s viral load becomes undetectable in the blood 12 weeks after treatment. If left untreated, chronic HCV can result in liver disease and cancer as well as premature death.
Treatment in the form of pan-genotypic direct-acting antivirals (DAAs) are prescribed to reduce viral load.
“The earlier forms of the DAAs performed better for some genotypes over others,” said Dr Kathy Jackson, Principal Scientist at the Victorian Infectious Diseases Reference Laboratory (VIDRL) at the Peter Doherty Institute for Infection and Immunity (Doherty Institute).
The varying performance of earlier DAAs necessitated the use of genotypic assays. This established which genotype was present in each patient, helping determine which treatment they would receive. In fact, genotyping HCV infections was a requirement for prescribing DAAs under the Pharmaceutical Benefits Scheme. However, this has changed since the development of pan-genotypic DAAs with the requirement being lifted.
“Now that pan-genotypic DAAs are available, genotyping is becoming less important,” Dr Jackson said, continuing, “You can just put a patient directly on the DAA treatment.”
Although the rate of HCV infection genotyping is declining, there are still several instances where it is useful, particularly in regard to determining reinfection.
“Patients these days can get hepatitis C, they can get treated, they can get reinfected. Without genotyping, it’s not apparent whether they’ve got the original infection or whether they’ve got a reoccurring genotype,” explained Dr Jackson.
If the genotypes or sequences of an active infection and a previously known infection don’t match, this can point toward a case of reinfection.
“The number for the viral load testing is probably still pretty stable. We're still trying to find as many patients with hep C as possible so that we can get them on treatment,” she continued.
“And the other reason to do sequencing is to look for drug resistance or resistance associated substitutions,” said Dr Jackson. However, as the drugs developed have improved, they are seeing less associated drug resistance.
Eliminating viral hepatitis as a major public health threat by 2030 is a key goal for the World Health Organization (WHO). Dr Kathy Jackson flags that although Australia is on track to reach this goal, more work needs to be done.
“We've been really good at treating the patients who are readily accessible and who may have been diagnosed in the past. But I think we've still got a long way to go to diagnose the patients that are out there who’ve got no idea they've got hepatitis C, and there could be a lot of those,” she elaborated.
Dr Jackson maintains that HCV is still a public health problem and emphasises the importance of developing an HCV vaccine to combat reinfection.