OT: Bats and Their Many Diseases
Why does it always come back to bats, when diseases are investigated like Covid, SARS, MERS, hundreds of other coronavirii, Hendra, Nipah, Marburg, a diverse range of influenza viruses, relatives of the human-infecting hepatitis C virus. and suspected Ebola? Bats stand alone in being natural hosts and yet are apparently unaffected, this having been noticed since 1932.
The bat-virus détente
Bats are the only mammal that can actually fly, not just glide. It is estimated that a bat’s metabolic rate can increase to up to 34 times over its resting level when it takes to the air. By comparison, rodents running to exhaustion exhibit an eightfold increase, and birds on the wing a doubling. Of course bats in the rodent family and birds are in the 'dinosaur' family.
Whenever a complex organism is infected with a pathogen its immune system goes into overdrive, to track down and kill the invader. When a virus injects itself into a cell it steals DNA and uses the cell's resources and machinery to replicate, eventually with the cell bursting with many more copies of the virus. Surrounding tissue develops an inflammatory response, which is like a HELP, HELP sign, calling disease-fighting mechanisms such as antibodies, killer T-cells, etc to the rescue.
BUT there is no regulation of the inflammatory response in most complex organisms, and it can run out of control. This is what kills many of those with Covid-19... a 'cytokine storm'. ('cyto'=cell, 'kine'= to move/divide)
Now with bats: "First, the bats mount a speedy but nuanced offensive that stops the virus from multiplying with abandon. Second, and perhaps more important, they dial down the activity of immune foot soldiers that might otherwise cause a massive inflammatory response that would do more damage than the virus itself.
“Bats have a lot of this good immune response —suppressing virus replication— that protects them,” Banerjee says. “And they have very little of the not-so-good immune response, which is inflammation.”
More in the article. Wipe out bats? "Bats are crucial pollinators of hundreds of plants including many agriculturally important ones. They aid in seed dispersal, and many are voracious eaters of insects — mosquitos and crop pests importantly among them. And eliminating bats can backfire, with deadly consequences: Killing Egyptian fruit bats in a mine in Uganda led to an influx of new bats and a Marburg virus outbreak, scientists think." (There's always a catch...)
Not only that, but they represent our only chance of understanding a unique and completely different way of fighting disease.
Carl A. Cook