Challenges to mapping the health risk of hepatitis A virus infection

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.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.Maps are valuable tools for epidemiologic research and application, and are particularly effective in communicating key public health messages to a wide range of audiences. One example of the importance of global risk maps relates to the display of vaccination recommendations for hepatitis A virus (HAV), an infectious disease strongly linked to income, access to clean water, and access to sanitation [1]. Most children in low-income areas become infected in early childhood when HAV infections are typically asymptomatic, and infection confers lifelong immunity. Thus, in low-income areas the incidence of infection is usually high, but the disease burden is low and hepatitis A is not considered to be a major public health problem. In contrast, hepatitis A is a growing public health concern in high-income areas where the infection rate is usually low, since many adults remain susceptible to HAV and are at risk of severe symptoms and death [2-4]. Additionally, hepatitis A may cause a significant economic burden to individuals, families, and communities, especially in areas with a sizeable