smallpox didn't die out until the 1970s or so. There wasn't a cholera vaccine until 1900, and people still contract it occasionally. And there were lots of 19th century wars (Crimea, Zulu, America, many many more). The real question is whether you'd have been liable to die in any of these ways. If you were rich and not living in cramped conditions, with access to a varied diet and safe water (possibly living in the countryside if you didn't need to find work in the cities), and able to avoid being pressed into the navy, you'd have had as good a chance as anyone.