Well I wasn't talking about something as drastic as a zombie apocalypse, but disease can effect a country's productivity quite a bit. Let's take a fairly recent example-Ebola. The epidemic is said to have cost $2.2bn in 2015 to the west African economies' GDP. Most of it because goods and services going out of those countries were stopped and investment (local and foreign) was discouraged. Many Epidemiologists agree that unlike the previous outbreaks in the past half century in Africa, Ebola is different. It could've been very easy to control if the virus had begun in isolated villages and tribes but Ebola became a problem only when it had spread to the overpopulated African city slums from where it quickly became a world scale epidemic.

Again what has it to do with human capital? On a more micro level you have an individual who is trained, driven and well-educated, so by all definitions a good human capital. If this individual gets sick and starts losing days of work, he is no longer a productive asset to the economy instead becomes a drain as he starrs consuning resources without contributing much to the economy (as callous as it is to call a sick person a drain it is true in a strictly economic sense). If this individual dies as a result of the disease the economy has now to bear the social cost of having had spent resources and time educating and training an individual without much output to show for it.

According to early economists, like Malthus, Disease and epidemic were a sort of "natural checks" on overpopulation. You mentioned China, they have a high rate and probability of epidemics as well (in fact they are in the middle of one right now but its poultry based). They also have a very strained healthcare system, understandably considering the sheer size of the population. But one thing they don't have is bad slums. They do have a thing called "villages in cities" which were actually old villages which got swallowed up by large cities as they expanded. These are often torn down or become ghost villages and even if they are retained as low income housing, most of its residents don't live in poverty. They are all fully or semi-employed. Because of such measures epidemics in cities can be controlled to a pretty good extent.

Thank you for your advice and debate. I truly appreciate it. Again I'll say that the point can be connected in a roudabout manner but probably isn't as relevant as one would like in an included argument. Next week shall be my first attempt at Css so its a learning curve for me and I'm grateful for your advice and insight. Thank you once again.