Definition of emerging viruses:
Known viruses that have newly appeared in a human population and is rapidly increasing in disease incidence.
Source of emerging viruses:
· Animals are usually the reservoirs of emerging viruses (zoonotic viruses).
· Viruses were probably endemic at low levels in localized areas.
· However, they could have “jumped” species, acquired a new host range and spread from there.
Examples of emerging viruses:
Dengue virus, Avian Influenza virus (e.g. H5N1 strain), SARS coronavirus, Nipah virus and Ebola virus.
http://bepast.org/docs/photos/nipah%20virus/nipah%20virus.jpg
Nipah Virus
http://m.blog.hu/li/lightscience/image/gpw-20050430a-fullsize-Ebola-virus-CDC-PHIL-ID-1181.jpg
Ebola Virus
http://ec.europa.eu/health/ph_threats/com/Influenza/images/influenza.jpg
Reasons for Emergence
Virus Factors
· Spontaneous evolution of a new virus entity
· Generation of a novel strain due to co-infection of different strains in an individual (random assortment)
Human Factors
· Concentration of people with shared lifestyle
o E.g. the sharing of hypodermic needles, unsafe sex
· Breakdown in public health
o Mainly in third world countries
· Climate change
o E.g. increased wet seasons will lead to more stagnant water which might make it more conducive for mosquito breeding in a particular area. Aedes mosquito is a vector of dengue fever. Thus, the spread of the dengue flavivirus will be enhanced.
· Man invading natural habitat of animal
o Deforestation for agricultural needs
o Closer to wild animals
o Increasing the possibility of zoonoses
