Discussion in 'Other Health News and Research' started by natasa778, Dec 1, 2014.
Interesting. I wonder which factor is more likely to do this?
A similar thing happened to syphilis: it became milder over time.
When syphilis first appeared in Naples in the 15th century (it was probably imported from the New World), this pathogen was far more deadly and downright awful than the syphilis we know today. When it first appeared, syphilis was so virulent that it killed within months, and there were gruesome descriptions of the flesh literally falling off the bodies of those with syphilis infections!
However pathogens are subject to evolutionary forces, which can change their virulence level over time. Evolutionary biologist Paul Ewald talks about how, depending on the circumstances, if a pathogen evolves to become more virulent and to kill more quickly, that pathogen can sometimes have less chances of transmission into new hosts (which is fundamental for its survival) compared to if it evolves into a milder, less virulent version. Milder versions of pathogens can have greater chances of survival because if their host lives longer, there can be more opportunities for that host to come into contact with and spreading the infection to new hosts.
Crowded environments such as cities, where there are numerous opportunities to come into contact with potential new hosts, tend to favor evolution towards milder versions of pathogens.
Yes, but that is usually believed to happen over longer periods of time. What is new in this case is that seems to be happening at a rapid speed. Or at least this is the first time such a rapid transformation has been observed
True, although the article said that there was only a small 10% reduction in the ability to replicate. Presumably this reduction has occurred over the last 25 - 30 years, in the time since HIV was first discovered in the 1980s.
I am not sure how quickly syphilis took to evolve to a more benign form.
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