Depends on why they're sick. They can carry and spread viruses and such.
No snakes do not need vaccinations or injections because when they are kept in captivity they will not carry viruses or diseases.
you get sick
Sheep can catch viruses which can make them sick but they don't have viruses all the time.
dead/inactive viruses. that's why you don't get sick. dead/inactive viruses. that's why you don't get sick.
Yellow Fever and Dengue fever are caused by viruses in the Flavivirus family. They are related but they are very different. Dengue viruses are transmitted by mosquitoes from infected people to healthy people. Yellow fever virus is also transmitted by mosquitoes from sick people to healthy people but may also be transmitted from infected monkeys to healthy monkeys or people.
You should wash your hands before and after you handle mice. They do carry many diseases.
Babies get sick for the same reason everybody does: viruses, bacteria and other diseases.
Even though you might not be sick, you still carry bacteria and even viruses in and on your body. Your sneeze or cough could still contaminate food.
shutup
Dont eat and dont sleep. Think about things that make you nervous. Your stomache will be in circles and it will feel funny. Its not exactly "sick sick" but it does the trick.
Viruses make us sick by invading our bodies and hijacking our cells to replicate themselves. This process can damage our cells and tissues, leading to symptoms of illness as our immune system responds to the infection.