The fossil record tells us what types, kinds, and numbers of organisms may have lived in the past, as well as what they ate, what age they lived in,.
Handwashing is one of the most important (and easiest) practices used to prevent transmission of bloodborne pathogens. Hands or other exposed skin should be thoroughly washed as soon as possible following an exposure incident. Use soft, antibacterial soap, if possible.
But these blood vessels are different from all the other blood vessels in our body. They are lined by a strange structure called the blood-brain barrier. It closely controls what is, and is not, allowed to leave the blood supply and enter the brain. It's your own personal customs and border security.