Why Does Hepatitis C Virus Disproportionately Affect Certain Groups?

Rates of hepatitis C virus (HCV) infection were 10% higher among immigrants in Canada than nonimmigrants, with refugees accounting for 30% of all diagnoses, according to a recent study that could help develop targeted screening for the disease.

The population-based, retrospective cohort study, published in Journal of Viral Hepatitis, examined trends in newly reported HCV diagnoses. It included 38,348 individuals, recruited in Quebec, Canada between January 1998-December 2018.

Investigators evaluated immigration status, age group, sex and region of origin of those diagnosed with HCV during the time period of the study.

“Although HCV rates decreased over the study for all groups, the annual decline was lower among immigrants,” the study authors, led by Ana Maria Passos-Castilho, a postdoctoral research fellow at the Centre for Clinical Epidemiology and McGill University, wrote. “As a result, the proportion of all HCV cases occurring among immigrants increased by 2.5-fold between the beginning and end of the study period.”

The study highlighted a delay in diagnosis among immigrants, for whom the average time to diagnosis after arrival in Quebec was 7.5 years throughout the study period.

Immigrants accounted for 14% of all HCV cases diagnosed during the study period, with rates increasing over time from 12% between 1998 and 2008 to 19% from 2009 to 2018. More immigrants diagnosed with HCV lived in urban settings at 91% compared with 63% of nonimmigrants.

Immigrants diagnosed with HCV also were older, with an average age of 47.7 years compared with 44.5 among nonimmigrants. A total of 54% of immigrants diagnosed with HCV were men, compared with 69% of nonimmigrants.

“The HCV epidemiology among immigrants generally reflects the HCV prevalence in their countries of origin when they lived there,” the authors wrote. “Immigrants born in countries with high-HCV-prevalence have consistently been found to have higher HCV prevalence (1.5–2 fold) compared with host populations, with those born in sub-Saharan Africa, Asia and middle-income Europe at the highest risk.”

The greatest proportion—about 20%—of HCV-diagnosed immigrants came from East Asia and Pacific region, though that rate declined over time from 24% during the first half of the study to 14% during the second half. The proportion of HCV-diagnosed immigrants coming from sub-Saharan Africa increased from 13% to 20% during those times, and the proportion from middle-income Europe and Central Asia rose from 9% to 15%.

Immigrants were less likely than nonimmigrants to be co-infected with HIV (2% compared with 4%) and less likely to have a history of injection drug use (3% compared with 22%). But they were more likely to be co-infected with hepatitis B virus (2% compared with 1%).

“Persisting delays in HCV diagnosis highlight an urgent need for targeted HCV screening among immigrants from high-HCV-prevalence countries,” the study authors wrote. “Our results may be generalizable to other low-HCV-prevalence countries that do not routinely screen for HCV among immigrants born in high-HCV-prevalence countries.

With increasing population mobility and ongoing immigration from high-HCV-prevalence countries, screening and treating immigrants will be key to achieving HCV elimination in Canada and other low-HCV-prevalence countries.”

This article originally appeared on Contagion Live.