EMERGING viruses!

What is emerging viruses?

-Emerging virueses are known viruses that has newly appeared in human population and is rapidly increasing in disease incidence.

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
-Breakdown in public health
-Climate change
-Man invading the natural habitat of animal

Spontaneous evolution of viruses
-Viral population are heterogenous
-High mutation rates
-> due to selection pressureRandom assortment

-H3N2 infects man, H5N1 infects birds
-H5 is efficient at attachment
-Co-infection of both
-Virus replicates inside host
-RNA strands transcribed
-Viral protein synthesized
-A new influenza virion formed, H5N2!
-Release of virus particles

Whats possible?
-H-Hemagglutin
-N-Neuraminidase
-16 different H types
- 9 different N types
-H1N1
-H3N2
-Only 4 strains of avian influenza virus are known to cause disease in humans: H5N2, H7N3, H7N7, H9N2

Breakdown in public health
-Not likely in developed countires
-Examples, HIV in Africa
cholera outbreak in Iraq
http://www.reliefweb.int/rw/RWB.NSF/db900SID/LSGZ-76QHDR?OpenDocument

Climate change and Viral disease
1) http://dsc.discovery.com/news/2009/01/27/mosquito-disease-warming.html
2) http://allafrica.com/stories/200901261750.html

Man invading Animal natural habitats
-Deforestation for agriculture needs
http://www.globalchange.umich.edu/globalchange2/current/lectures/deforest/deforest.html

-Closer to wild animals
- Increase possibility of zoonoes

Statistics of emerging viruses over last 6 years
http://www.dh.gov.uk/en/Publicationsandstatistics/Publications/AnnualReports/Browsable/DH_4874410