ABSTRACT
The emergence of infectious diseases usually encompasses any of three situations: (1) appearance of a known agent in a new geographic area or population or increase of incidence of the disease, (2) evolution of a pathogen to increased pathogenicity or transmissibility, and (3) recognition of a previously unknown agent (Fauci, 2005; Taylor et al., 2001). It is estimated that 12% of human infectious diseases (of bacterial, fungal, and viral nature) can be considered emerging, with majority having an animal source. In many instances, the hosts of emerging zoonotic viruses have proven to be small mammals. Some of the major factors responsible for the emergence of infectious diseases include ecological changes, such as those due to agricultural or economic development or anomalies in climate, microbial adaptation and change, and the breakdown of public health measures. Increasing international travel, trafcking in wildlife, political instability, and bioterrorism have made also emerging infectious diseases a global concern. In this context, viral hemorrhagic fevers (VHFs) warrant specic emphasis because of their high rates of severe illness and death and the potential for rapid dissemination by human-to-human transmission. VHFs are caused by infection with several negative-stranded RNA viruses belonging to four families: Arenaviridae, Bunyaviridae, Filoviridae, and Flaviviridae. Although clinical management of VHFs is primarily supportive, early diagnosis is needed in order to timely implement infection control measures to combat further spread of the disease. This is especially important if VHF pathogens are encountered out of their traditional geographic areas. Of the Old World (OW)
16.1 Introduction ..........................................................................................................................287 16.1.1 General Characteristics of Arenaviruses ..................................................................288 16.1.2 Host Cellular Receptors: Determinants of Pathogenesis
and Zoonotic Transmission ....................................................................................... 289 16.2 Viral Hemorrhagic Fevers Caused by Arenaviruses ............................................................290
