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Background: World maps are among the most effective ways to convey public health
messages such as recommended vaccinations, but creating a useful and valid map requires
careful deliberation. The changing epidemiology of hepatitis A virus (HAV) in many world
regions heightens the need for up-to-date risk maps. HAV infection is usually asymptomatic in
children, so low-income areas with high incidence rates usually have a low burden of disease.
In higher-income areas, many adults remain susceptible to the virus and, if infected, often
experience severe disease.
Results: Several challenges associated with presenting hepatitis A risk using maps were
identified, including the need to decide whether prior infection or continued susceptibility more
aptly indicates risk, whether to display incidence or prevalence, how to distinguish between
different levels of risk, how to display changes in risk over time, how to present complex
information to target audiences, and how to handle missing or obsolete data.
Conclusion: For future maps to be comparable across place and time, we propose the use of
the age at midpoint of population susceptibility as a standard indicator for the level of hepatitis A
endemicity within a world region. We also call for the creation of an accessible active database
for population-based age-specific HAV seroprevalence and incidence studies. Health risk maps
for other conditions with rapidly changing epidemiology would benefit from similar strategies.