Emerging viral infections

Abstract

There has been considerable recent emphases on possible threats due to the appearance of new virus diseases or the re-emergence of older infections with new properties. Virus genomes are constantly evolving, and selection at a number of levels continually operates to favour those particular strains that 'function best' in the environment available to them. This process is further disturbed by the introduction of viruses from one host species to another, and by disruption to the environment that provides the selection process, e.g. by man-made intervention, natural disaster, etc. In recent times, a number of important virus infections have been eradicated or controlled to a significant extent (smallpox, polio, measles), others have increased dramatically (e.g. dengue) or extended into previously uninfected populations of humans (Ebola, Hantaviruses). HIV is the most dramatic example of a new virus thought to have not caused significant human infection until recently. Despite popular fears about the appearance of deadly 'super' strains of new viruses, overall changes in human behaviour and the relationship between humans and the environment are likely to be the major factors determining future trends in virus infections.