Emerging and Re-emerging Viral Infections

Natural focal diseases are caused by biological agents associated withspecific landscapes. The natural focus of such diseases is defined as anynatural ecosystem containing the pathogen’s population as an essentialcomponent. In such context, the agent circulates independently on humanpresence, and humans may become accidentally infected through contact with vectors or reservoirs. Some viruses (i.e., tick-borne encephalitis andCongo-Crimean hemorrhagic fever virus) are paradigmatic examples of natural focal diseases. When environmental changes, increase of reser-voir/vector populations, demographic pressure, and/or changes in humanbehavior occur, increased risk of exposure to the pathogen may lead to clusters of cases or even to larger outbreaks. Intervention is often nothighly cost-effective, thus only a few examples of large-scale or eventargeted vaccination campaigns are reported in the international literature.To develop intervention models, risk assessment through disease mappingis an essential component of the response against these neglected threatsand key to the design of prevention strategies, especially when effectivevaccines against the disease are available.