## Contagious College Campuses: Why meningitis and other diseases spread so easily on college campuses

https://blogs.scientificamerican.com/guest-blog/why-is-meningitis-still-causing-deaths-on-u-s-college-campuses/

This summer, before leaving for my first semester at Cornell, I met with my doctor to go over medical requirements for the school and have my yearly physical. As it was finishing, my doctor realized something: I hadn’t yet gotten the meningitis vaccine. Although I’m not the biggest fan of shots, I quickly learned that the shot was well worth it. meningitis is a virus that affects the brain and spinal cord, and up to 15% of those contract it may die, possibly even within 24 hours. While the disease is deadly, since there is a vaccine, one would expect cases of meningitis, and certainly deaths from the disease, to be relatively low. While many states have have requirements for incoming freshmen to vaccinated, the vaccine is not required in 12 states. This has led to some disturbing consequences. As the article discusses, in between March 2013 and February 2016, there were outbreaks of meningitis on 5 college campuses, resulting in multiple student deaths.

Meningitis spreads through respiratory and throat secretions, most commonly spit, and in a condensed environment like a college campus, with students sharing spaces and drinks, there is a much higher risk of the disease spreading. This risk, however, would be a lot lower if all students were vaccinated. Indeed, if this were the case, we wouldn’t have a network to observe at all, as the probability p of any student spreading the disease to another would be 0, since it would be impossible to give a vaccinated person a disease. This is one benefit of being on a college campus, as the college administrators are able to control the network and make sure that every person, or node, in the network has no chance of catching meningitis. In the outside world, where no one can control vaccinations, there is a higher chance of interacting with someone who either isn’t vaccinated or has already contracted the disease.

However, a college campus with no vaccination requirements is a completely different situation. When it comes to unvaccinated students, there is a probability p > 0 that students will catch the disease. This means we can use information from class to model the spread of meningitis. With probability p and the number of people an infected person interacts with k, we can say the reproductive number, R0, is equal to p times k. If R0 is less than 1, then with probability 1, the disease will die out in a finite number of waves of spreading. If R0 is greater than 1, then with probability greater than 0 the disease persists by continually infecting people. Therefore, administrators at schools with this problem must focus on trying to reduce p and k, making the spread of disease finite. For example, when it is discovered that a person is contagious, they will limit the exposure the patient has to other students, reducing k. And while it may not be mandatory for a student to be vaccinated, it is still possible to encourage students to be vaccinated or offer low cost, easy-to-access vaccinations on campus, decreasing p. When it comes down to it, campuses have certainly done a good job of preventing wide-spread outbreaks of meningitis by using strategies like those above, but in the end no student should die of such an easily preventable disease.