Could this be Yellow fever?

I thought that was a rickettsia.. (will have to look that up)

I see I'm wrong and it is a virus.

I presume people had viruses through the ages, whether they were discovered then or not.

It would be a little difficult to pin down the first disease seeing as how viruses have existed for a couple of hundred million years.

Jonathan (Maybe longer than that)Nation

First treated virus?

From Wiki:

Early forms of vaccination were developed in ancient China as early as 200 B.C.[1] Scholar Ole Lund comments: "The earliest documented examples of vaccination are from India and China in the 17th century, where vaccination with powdered scabs from people infected with smallpox was used to protect against the disease. Smallpox used to be a common disease throughout the world and 20% to 30% of infected persons died from the disease. Smallpox was responsible for 8 to 20% of all deaths in several European countries in the 18th century. The tradition of vaccination may have originated in India in AD 1000."[4] The mention of vaccination in the Sact'eya Grantham, an Ayurvedic text, was noted by the French scholar Henri Marie Husson in the journal Dictionaire des sciences me`dicales.[5] Almroth Wright, the professor of pathology at Netley, further helped shape the future of vaccination by conducting limited experiments on the professional staff at Netly, including himself. The outcome of these experiments resulted in further development of vaccination in Europe.[6] The Anatolian Ottoman Turks knew about methods of vaccination about a hundred years before Edward Jenner to whom the discovery is attributed. They called vaccination Ashi or engrafting, which they used to apply to their children with cowpox taken from the breast of cattle. This kind of vaccination and other forms of variolation were introduced into England by Lady Montagu, a famous English letter-writer and wife of the English ambassador at Istanbul between 1716 and 1718, who'd almost died from smallpox as a young adult and was physically scarred from it. She came across the Turkish methods of vaccination, consenting to have her son inoculated by the Embassy surgeon Charles Maitland in the Turkish way. Lady Montagu wrote to her sister and friends in England describing the process in details. On her return to England she continued to propagate the Turkish tradition of vaccination and had many of her relatives inoculated. The breakthrough came when a scientific description of the vaccination operation was submitted to the Royal Society in 1724 by Dr Emmanual Timoni, who had been the Montagu’s family physician in Istanbul. Inoculation was adopted both in England and in France nearly half a century before Jenner's famous smallpox vaccine of 1796.[7]