The Pox

The Pox, also known as Smallpox (Variola Major and Variola Minor), is a viral infection that kills around 30% of those infected depending on circumstances. Mortality among children is much higher. It often leaves severe scarring and can cause blindness if severe lesions develop around the eyes. It is highly transmissible and is usually passed through the air simply by talking to an infected person or spending enough time in the same room as an infected person. When passed in this way the infection starts in the mucal tissues of the nose and sinus where it spreads quickly to the lungs and lymph system and then around the body. Small Pox infections can be spread through skin-to-skin contact and blood contact though infections spread in this way are usually much less severe (which led to the development of the first inoculations).
Inoculations are first hinted at in 10th century China though the first definitive mention of inoculations is from 16th century China. Inoculations were used in India by the 17th century (and may have been done centuries earlier than that) and in Ethiopia and West Africa by the early 18th century. Parts of Europe and America began inoculating nobles and wealthy people in the late 18th century. Inoculations reduced the mortality rate of smallpox from 30% (for ordinary smallpox infections) to less than 1% as well as reducing the amount of scarring that survivors were faced with.
Initially, inoculations appear to have been done by crushing up the secretions of pustules from people who were recovering from Small Pox and then used to scratch the skin of someone who had not been infected yet (Variolation). This caused the person scratched to develop a milder case of Small Pox that produced less scarring and gave them immunity to the virus. These early inoculations were far from perfect with some people still developing severe cases and dying but were better than no protection at all. Over the following years, a variety of different methods were developed that were safer. This culminated in 1798 with Edward Jenner's use of the cowpox virus (instead of smallpox) introduced through a syringe (Vaccination) that was safer and more effective than the older method of variolation. Edward Jenner was not the first to use cowpox to inoculate against smallpox but he was the first to document and then publish the results of his experiments.

Causes

The Variola Major virus. The Variola Minor virus was much less common but was also less severe.

Symptoms

Incubation period of 7-10 days - the patient has no symptoms, doesn't know they are sick, and are not contagious.
Early symptoms period of 2-3 days - the patient suffers from fever, diarrhea, and vomiting but does not display a rash. The patient is highly contagious at this point.
Early rash period of 2-3 days - the rash starts inside the mouth and nose (unless the infection is gained through a scratch then the rash will start around the area of the scratch). Small bumps form quickly and spread from the mouth to the rest of the face, back, arms and legs.
Late Rash period of 3-4 weeks - the rash spreads to the palms of the hands and the soles of the feet as the bumps begin filling with pus. After a week the pus-filled bumps become pustules (pus-encrusted scabs). These pustules then begin falling off over the next two to three weeks. The patient is infectious until the last pustule has fallen off.

Treatment

No known treatments, only preventative care through inoculation.

Prognosis

Among adults "ordinary" smallpox (Variola Major) infections led to a 30% chance of death and an 80% chance of scarring, often severe. Blindness was also possible depending on the severity of lesions that could develop around the eyes.
Ordinary smallpox infections made up 90% of the cases. The other 10% of infections were made up of "modified" infections among vaccinated people that are almost never fatal, and "malignant" (typically children) and "hemorrhagic" (typically adult) cases that are almost always fatal.

Type

Viral