nature

if a mosquito bites a horse 

then the horse can rub it's side against a tree 

so that the mosquito is crushed and killed 

and if the mosquito bites the horse on the upper back 

then the horse could roll on the ground 

so that the mosquito is crushed and killed 

but the horse will probably not waste energy and time 

to roll around on the ground 

in order to kill a few mosquitoes 

so an animal can sometimes deal with parasites 

if a mosquito bites a human 

then the human can slap the mosquito 

so that the mosquito is crushed and killed 

and if the mosquito bites the human on the back 

then the human can rub it's back against a wall 

so that the mosquito is crushed and killed 

but if unrighteous humans 

uses other humans as tools 

to abuse and torture a righteous human 

then it's difficult for the righteous human to defend itself 

so humans can deal with animal parasites 

but most humans can't deal with human parasites