Epidemics don’t necessarily decline because everyone has been infected, but also end because there aren’t enough infected people left to sustain transmission
From influenza to plague, the number of cases in a real epidemic often rises exponentially at first. After a while, the disease reaches a peak level, and then the number of new cases starts to decrease. When McKendrick and Kermack began their research (1927, in a paper titled ‘A Contribution to the Mathematical Theory of Epidemics), people generally gave two possible reasons for the decline. Either the epidemic faded away because the infection had become less potent over time, or because there were no susceptible people left – everyone had been infected and either died or become immune.
In their model, McKendrick and Kermack assumed that the pathogen stayed the same throughout the epidemic; the infection did not weaken over time. And yet the model still produced an eventual decline in cases. When the pair compared the model to the 1905 outbreak of plague in Bombay, the predicted number of cases matched the real disease level.
So was the decrease in infection caused by a lack of susceptible people? Apparently not: in the model, there were always some susceptible individuals remaining at the end of the outbreak. McKendrick and Kermack had demonstrated that epidemics don’t necessarily decline because everyone has been infected. They can also end because there aren’t enough infected people left to sustain transmission. Once enough people are immune, infected individuals are unlikely to meet another susceptible person, which means that they generally recover before infecting others.
Source : The calculus of contagion, 16 September 2014, Aeon.co
I revere [trees] when they live in tribes and families, in forests and groves. And even more I revere them when they stand alone. They are like lonely persons. Not like hermits who have stolen away out of some weakness, but like great, solitary men, like Beethoven and Nietzsche. In their highest boughs the world rustles, their roots rest in infinity; but they do not lose themselves there, they struggle with all the force of their lives for one thing only: to fulfill themselves according to their own laws, to build up their own form, to represent themselves. […] A tree says: The attempt and the risk that the eternal mother took with me is unique, unique the form and veins of my skin, unique the smallest play of leaves in my branches and the smallest scar on my bark. I was made to form and reveal the eternal in my smallest special detail.
Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone ...
The very word virus began as a contradiction. We inherited the word from the Roman Empire, where it meant, at once, the venom of a snake or the semen of a man. Creation and destruction in one word.
The assumption that animals are without rights and the illusion that our treatment of them has no moral significance is a positively outrageous example of Western crudity and barbarity. Universal compassion is the only guarantee of morality.