Ask any teacher and they will tell you about all the infections they have acquired from their children. Children are the perfect transmitters of disease because of several factors. They are young, so their immune systems have not learned to get rid of all diseases. They have not grasped the concept of washing their hands each and every time. And they share a lot. They hug and kiss each other and others, and they share their lunches and drinks with each other. Younger children explore their world by tasting it. Yet the ability to infect others does not stop with children. Young adults can also be the epicenters of outbreaks.
Young adults in college dorms or other group settings transmit diseases because of their behavior, their living arrangements, and their social situation. Unprotected sex transmits, of course, sexually transmitted diseases. Drug use may transmit blood-borne infections like hepatitis B and hepatitis C. Living in close quarters allows respiratory infections to jump from one person to another easily. Sharing drinks (like at a party) may transmit anything from norovirus (a virus that causes vomiting and diarrhea) to the more serious meningitis.
Meningitis is an inflammation of the meninges, layers of tissue that cover the brain and spinal cord. Viral meningitis can be the result of a number of viruses, including herpes virus and West Nile virus. Viral meningitis is usually milder than bacterial meningitis, with only supportive treatment given to counter the fever and meninges' inflammation. On the other hand, bacterial meningitis is far more serious. Just think of all the bacteria eating away at your meninges (zombie bacteria?).
Bacterial meningitis can be caused by several bacteria, including Streptococcus pneumoniae, Neisseria meningitis, and Haemophilus influenzae. There is a vaccine against Strep pneumo and H. flu (as they are commonly called). The most serious is N. mening (as it is commonly called) since up to 14% of those who who get meningitis from it die. If you recover from it, you have a one-in-ten chance of further complications, like loss of hearing, mental retardation, or even worse... you can lose your limbs.
N. mening can be present in people's nasal cavities and in their throats. When they are there without causing disease, they are said to be normal flora. However, if something happens to upset the habitat of the normal flora, like an upper respiratory infection, the bacteria might get into the person's blood and travel to the meninges (causing what is called meningococcal infection). The person can also infect others through sneezing, kissing, or other ways of sharing their saliva and respiratory tract secretions. (There's a reason why people who spit while they talk are unappealing.)
So you can imagine why public health authorities get a little bent out of shape when there is a report of a young person with meningitis especially if it's one who lives in a group setting. This is because all of those people who lived with the sick person (the case) need to be identified and offered antibiotics. Sometimes, this translates to hours of work in tracking down hundreds of people. And, all the while, the disease could have been prevented by a vaccine.
Sure, some would say that vaccinating everyone (at $50 to $80 a shot) would be costly and maybe wasteful. But tell that to the parents of those who have died or suffered irreparable damage from meningococcal infection. Tell that to the star athlete who lost all limbs. Those $80 sound like a heck of a deal after all that... having everyone vaccinated and practicing care when they live together sounds even better.