Challenges to mapping the health risk of hepatitis A virus infection.
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.


CONCLUSIONS
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.
Expanded Program on Immunization, Department of Immunization, Vaccines, and Biologicals, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland.
Khayriyyah
K
Mohd Hanafiah
Kathryn H
KH
Jacobsen
Steven T
ST
Wiersma
D000328:Adult; D000367:Age Factors; D002648:Child; D004198:Disease Susceptibility / Q000453:epidemiology; D015340:Epidemiologic Research Design; D040362:Geographic Information Systems; D014943:Global Health; D006506:Hepatitis A / Q000453:epidemiology* / Q000276:immunology; D030041:Hepatitis A virus / Q000302:isolation & purification; D006801:Humans; D007109:Immunity; D008377:Maps as Topic; D018570:Risk Assessment; D012499:Sanitation / Q000592:standards / Q000639:trends; D016036:Seroepidemiologic Studies; D012959:Socioeconomic Factors