Evolutionary Biology Important re Bird and Human Flu
Interesting paper (to me!) by Professor Ewald -
Against the Most Dangerous Emerging Pathogens: Insights from Evolutionary Biology
- covers pathogen characteristics that indicate they could cause dangerous diseases.
Has a checklist, to assess if a pathogen could be dangerous - it could be if answer is yes to any of the following:
Does it have a tendency for waterborne transmission?
Is it vector-borne with the ability to use humans as part of the life cycle?
If it is directly transmitted, is it durable in the external environment? Is it attendant-borne? Is it needle-borne?*
If it is sexually transmitted, is it mutation-prone with a tropism for critical cell types or does it have invasive or oncogenic tendencies?
Relevant to human and bird (poultry) flu:
With regard to the emergence of virulent variants from established pathogens, the influenza viruses circulating at the Western Front during World War I would be considered dangerous because barriers to transmission from immobile hosts were removed by cultural practices and because influenza virus is mutation prone. It is, therefore, not surprising that the Western Front has been identified as the source of the highly lethal variants of the 1918 influenza pandemic and that a pandemic of this severity has never recurred. More importantly, evolutionary considerations suggest that such a lethal pandemic will not recur unless influenza viruses are again exposed to opportunities that allow transmission from immobile hosts, as they are on poultry farms where highly lethal influenza outbreaks periodically emerge.
(I learned of this through an article in New Republic, by Wendy Orent, saying we are not facing a pandemic of highly lethal flu, as don't have the necessary conditions [inc chance for people laid low by flu to still readily transmit to others]; subscription needed to view article I believe.)