The Monster Virus, a name penned by the tabloids that first reported on the disease, is a strange virus that someone changes the body of whoever into a monster. It is not known how exactly these people change. Theories have been thrown out: an act of God, a mad scientist, or the coming of real life X-Men. However after a few years of trying to hide it in order to not cause a mass panic, the government was forced to reveal its existence with the evidence stacking up against them.
It is currently not know how the disease spreads. Patient Zero was quarantined, yet another victim appeared only a month after he was quarantined, in a completely different continent. Patient Zero had never gone to said continent and never had a reason to do so. There isn't a pattern to the way the virus spreads so predicting who it will affect next is impossible. Sometimes entire families will be affected at the same time. Symptoms before the change can be easily spotted. They include: eating more, sleeping more, labored breathing, a feeling of your body shifting when nothing is happening, vomiting, and a general fever.
The monsters that the sick will often transform into tend to lean into mythical monsters from a variety of folklore. Lamia, Dullahans, Centaurs to name a few. Other monsters seem to take some characteristics of other animals and apply them to a human body, not connected to any sort of mythology but just to normal animals like a dog or cat. Some of the more unique transformations have the subject transforming into something completely unimaginable, some staying human but growing extra limbs or one of their body parts becoming their entire body. The subject may have some resemblance to their old self, but also may look completely different.
Gender and Age are also affected. There have been numerous cases where a Male may turn into a female monster and vice versa. While there have been no cases of someone younger frowning older suddenly, a couple of cases have seen people between the ages of 40-90 suddenly growing younger by a simple couple of years but some cases have regressed back to a child.
Mental Changes have been documented, but most are in regards in controlling their new bodies. Sexuality may also change though cases of it are fairly uncommon.
Unfortunately, while the entire world looks for a cure that seems a far way off. However as the transformation is virtually painless, takes only two days to go through completely and can be detected a good month before it happens (through some telltale signs such as labored breathing, eating more, sleeping more and a strange feeling of your body shifting), it is important to retain some sense of order. This isn't some world ending event. No one had died directly from the virus. They still have a sense of intelligence and humanity within them. None of the changed have truly turned into monsters, only their bodies have. To this end it is important to let the people affected to continue to live their lives after they have changed. After all, despite their new bodies, they are still human.