Emerging viruses are those "whose incidence in humans has increased in the past 2 decades or threatens to increase in the near future." This week's Topic in Depth focuses on sites related to viruses, particularly those that are considered "emerging."

The first site (1) is an essay by Alison Jacobson of the University of Capetown that discusses some emerging and potentially emerging viruses, along with factors that contribute to the threat. From a US government interagency working group, the second report (2) focuses on the responses to infectious disease outbreaks, including drugs, vaccines, and government response. A World Health Organization site (3) highlights recent reports of infectious disease, archived by date and by disease. This ThinkQuest site (4) gives a basic introduction to viruses and how they cause infections. An online virology tutorial (5) by Ed Rybicki of the University of Cape Town serves as a lesson on the basics of virology for a more advanced student. The next two sites focus on the specifics of selected viruses. From the Institute for Molecular Virology (6) comes a resource on Marburg and Ebola viruses, and from the National Biological Information Infrastructure (7) is a site on West Nile Virus. The last resource (8) is a scholarly journal from the Centers for Disease Control that presents some of the latest scientific research on emerging diseases.