The spread of hepatitis C virus genotype 1a in North America: a retrospective phylogenetic study

Abstract

Background The timing of the initial spread of hepatitis C genotype 1a in North America is controversial. In particular how and when HCV reached extraordinary prevalence in specific demographic groups remains unclear. We sought to quantify, using all available HCV sequence data and phylodynamic methods the timing of the spread of HCV genotype 1a in North America. Methods We screened 45,316 publicly available HCV genotype 1a sequences for location and genotype then conducted phylogenetic analyses of available North American sequences from five HCV genes (E1, E2, NS2, NS4B, NS5B), with an emphasis on including as many sequences with early collection dates as possible. We inferred the historical population dynamics of this regional epidemic for all five HCV gene regions using Bayesian skyline plots. Findings Our analyses suggest that the bulk of the early spread of genotype 1a in North America occurred prior to 1965, and that the HCV epidemic has undergone relatively little expansion since 1965. Furthermore, our results indicate that the HCV epidemic has stabilized as of the early 1990’s. These results were robust across all five HCV gene regions analyzed. Interpretation Our results reveal the early HCV epidemic dynamics in North America. Importantly, the expansion of genotype 1a prior to 1965 suggests that nosocomial or iatrogenic factors rather than past sporadic behavioral risk (i.e.: experimentation with injection drug use, unsafe tattooing, high risk sex, travel to high endemic areas) were key contributors to the HCV epidemic in North America. Our results may also reduce stigmatization around HCV screening and diagnosis, potentially increasing rates of HCV screening and treatment.

Historical Trends in the Hepatitis C Virus Epidemics in North America and Australia

“…For example, the subtype 1a analysis in Australia, where the distance between the predicted root and the oldest available sequence is the largest, the HPD intervals around tMRCA are also large. The robustness of coalescent analyses in predicting HCV epidemics has already been established [18], and a recent study using this method on subtype 1a data in North America yielded a very similar prediction to that reported here regarding the timing of the epidemic [31]. Regarding the epidemiological modeling, the data are dependent on reported numbers in national surveys and notification systems, which may be affected by underreporting.…”

Measuring Adherence to Hepatitis C Direct-Acting Antiviral Medications: Using the VAS in an HCV Treatment Clinic

“…transfusions. 27 Such exposure is now largely prevented through standard infection control practices. Some baby boomers may also have been infected through injection drug use or other risk behaviors.…”

Improving support and education of low‐income baby boomers diagnosed with chronic hepatitis C virus infection through universal screening

“…These reactions to the disease have been cited as contributing to delay in HCV diagnosis of up to 28 years in the UK (Harris, Ward, & Gore, ) and may also prompt patients to avoid receiving care after diagnosis. Patients and their families also need to be educated about HCV so that the patient diagnosis is not always seen as being due to personal behaviours such as injection drug use because it is now understood to have diverse causes including incidental infection through routine health care decades ago (Joy et al., ). Furthermore, patients and families need to learn approaches to reduce the risk of transmission and how to change behaviours that can accelerate disease such alcohol use.…”

“…Most subjects admitted to worrying about how their lifestyle and substance use behaviours might have resulted in HCV infection. Although it is important to reinforce eliminating risky behaviours such as sharing dirty needles, new analyses of phylogenetic patterns of HCV infection in the USA suggested that nosocomial/iatrogenic factors likely played a major role in HCV transmission from the 1940s through 1960s when, for example, patients could have been inadvertently infected because of ineffective sterilisation practices (Joy et al., ). Destigmatising how patients acquired HCV can alleviate some of the strain of dealing with this diagnosis and may also reduce the sense of isolation because of being ashamed to share this diagnosis with others.…”