Measly Problems

Eric Lis

With measles making world headlines these last few weeks, this seems like an opportune time to discuss outbreaks. Tempting as it is, I don't intend to use this space to weigh in on the debate for and against vaccines, in large part because I think calling it a "debate" gives the unnecessary illusion of credence to the anti-vaccination movement, but more importantly because vaccination isn't relevant to most fantasy game settings. Instead, we can use measles as an example of a disease which is probably a very real health problem in fantasy settings.

Measles is a viral illness which causes a high fever and a distinctive rash. Measles is incredibly infectious; prior to vaccination, about 90% of the population could expect to contract it at some point in their lives, most before the age of 15. The virus spreads primarily through the air when people cough or sneeze, and is thought to be able to survive for a good few hours outside of the body.

From the time of infection, it takes about 1-2 weeks for symptoms to appear, usually starting with symptoms of the common cold such as cough, runny nose, and red eyes. Most people will be infectious by this time. Within a week, the classic rash of measles begins to appear, as white spots inside the mouth followed by the emergence of red spots that starts on the face which spread downwards over the rest of the body. The rash persists for another 1-2 weeks, and the infected person is still infectious for another few days after the rash resolves. Throughout this time, spread of the virus to different tissues can cause a variety of complications, including gut upset (about one infected person in ten), pneumonia (about one in twenty), and encephalitis (about one in every thousand).

Even today, it remains one of the world's most lethal childhood diseases. Depending on the source you read, measles killed anywhere between 1 to 30 out of every thousand people infected. Among children who are already malnourished or sick, the death toll may be higher than one in ten, and the very limited data available from before the age of modern medicine suggests that this number was perhaps even higher in the time periods when most fantasy campaigns are set. Cause of death is usually pneumonia or encephalitis, and we don't know how many survivors of encephalitis are left with permanent brain damage.

When the human body fights off measles, the body retains a fairly good immunity which lasts for the rest of life, barring the development of another illness that weakens the immune system. As with many diseases, this is one aspect that's very interesting for us in a fantasy game setting, because it changes what population the disease afflicts the most. A person who is magically cured of measles will likely fail to develop immunity to the virus, as the body needs time and exposure to produce antibodies. Among poorer people who don't have access to magical healing, measles is likely to be seen as a feared disease which kills an alarming number of children, but which afflicts them only once. Among the rich, however, who are more likely to take a sick baby to the cleric immediately, measles may rarely kill, but it's a debilitating disease that people inexplicably get over and over again during their lives. In this sort of situation, the rich act as a sort of reservoir for the virus, perpetually re-exposing their own serfs and servants and ensuring that the next outbreak is only ever one playgroup away.

So with all that said, let's consider how a measles outbreak might happen in a medieval fantasy setting. For narrative or dramatic purposes, an outbreak might start with an evil cleric magically afflicting poor townsfolk, but the virus is probably more than common enough to start an outbreak without any help. Imagine a typical fantasy city of ten or twenty thousand people, with the predictable neighbourhoods of nobles, districts of temples, and thousands of poor and downtrodden crammed together in back-alleys and shanty-towns. Due to patterns of natural immunity, the virus tends to appear and disappear in cycles, as a generation of mostly-immune people give rise to a new generation of mostly non-immune people. A single index case of measles appears in the city's slums. At first it looks like any other viral infection, so no special precautions are taken, and by the time a rash starts to appear another ten to twenty people have been exposed, have developed the first symptoms and been in contact with another ten or twenty each. Within a month, the city's rulership becomes aware of a plague among the poor, and depending on whether this is light or dark fantasy, the nobility might try to help treat it or try to encourage its spread. With two or three hundred people infected, anywhere from five to fifty people have already died, and panic is starting to be more widespread than rash. When a couple of slumming lordlings or ambitious panhandlers cross the borders between neighbourhoods, the virus reaches the artisans, merchants, and nobility, where it begins to spread even faster. If they haven't yet, then it's likely at this point that the temples get involved, and cure spells begin flying left and right. We now run into two narratively-useful problems. First, in a city of, say, twenty thousand people, there are only so many clerics; even assuming a few high-level casters, magical healing is probably only available for three to four hundred people per day at most, and depending on what sort of temples the city has, this may or may not be affordable to many of the sick. Second, a noble who receives magical healing instantly recovers, but doesn't become immune, so unless they begin to quarantine themselves, the rich and powerful get infected again... and again... and again. Even a wealthy house could find itself wiped out if its coffers are drained of an extra thousand gold per month, potentially destabilizing a city's economy or sending paranoid nobles on witch-hunts for the source of the "curse" that's been laid on them. Naturally, a group of enterprising adventurers could get drawn into this at any stage in the narrative and at the behest of any of a hundred interested parties. 

More than four years ago, Dr. Eris Lis, M.D., began writing a series of brilliant and informative posts on RPGs through the eyes of a medical professional, and this is the one that appeared here on February 8, 2015. Lis is a physician, gamer, and author of the Skirmisher Publishing LLC OGL sourcebook Insults & Injuries, which is also available for the Pathfinder RPG system