Mapping Core Hepatitis C Areas Improves Targeted Treatment

Zahid Butt, MBBS, MSc, PhD

Mapping techniques for identifying ‘core areas’ for transmission of bacterial sexually transmitted diseases have now been applied to hepatitis C virus (HCV) infections by Canadian investigators, who anticipate this approach will facilitate HCV prevention and intervention programs.

Lead author Zahid Butt, MBBS, MSc, PhD, of the School of Population and Public Health at the University of British Columbia, and a team sought analysis on the application of core theory and spatial analysis to HCV infections, told MD Magazine® that he expects that the mapping techniques will yield significant public health benefits.

"They can guide HCV prevention and care services such as needle and syringe distribution, supervised consumption sites, and overdose prevention sites, which can help reduce the incidence of HCV in the community," Butt said. "Additionally, they can optimize resource allocation and guide service delivery such as HCV treatment to these areas to reduce transmission of HCV."

Butt and colleagues point out that while spatial epidemiological research with HCV has delineated ‘hot spots’ for infection, it has not previously differentiated between geographic clusters and core areas.

"For effective HCV prevention and intervention planning, it is essential to know if a geographic cluster of HCV infection is a core area, non-core area or outbreak cluster, indicated by its stability and persistence over time and space," the investigators explained.

Time is essential for defining core areas, with such areas reflecting sustained and persistent infections of periods of 5 years or longer, in contrast to non-core areas or areas of outbreaks of shorter duration.

Butt and colleagues identified a total of 65,283 cases of diagnosed HCV from the British Columbia (BC) Hepatitis Testers Cohort (BH-HTC), which comprised an approximate 1.5 million BC residents who were tested for HCV between 1990-2103. They stratified the incidence data into 5 time periods of several years each to ascertain the temporal component of infection transmission; and applied 4 methods of spatial analysis to ascertain the geographic component that, together, could define core areas for HCV infection.

The investigators found good consistency across the 4 methods used for spatial mapping of core areas. There were significant clustering of HCV cases primarily in urban areas, but also in population centers supporting rural and remote communities. One major cluster of HCV transmission in Greater Vancouver was found to have persisted for nearly 20 years.

They point out that identifying non-core areas in the process is also important from a surveillance standpoint, as these could become core areas if appropriate interventions to address causes of outbreak or higher transmission are not implemented.

"As this method can be integrated into health systems, core areas can be used for evaluation of HCV prevention/elimination programs and their impact over time," Butt told MD Magazine®. "Real time application of core area methodology can help in identifying new HCV cases and outbreaks, gaps in services, testing and treatment of HCV and evaluation of services over time."

The study, Applying Core Theory and Spatial Analysis to Identify Hepatitis C Virus Infection "Core Areas" in British Columbia, Canada, was published online in the Journal of Viral Hepatitis.