There were infections in the New World before 1492 that were not present in the Old (Chargas' disease, for instance). There were those it shared with the Old World, certainly one or more of the treponematoses (a category including syphilis) and possibly tuberculosis; but the list is short, very short.
alkali meaning, definition, what is alkali: a substance that has the opposite effect or chemical behaviour to an acid. Learn more.
Alkaline means that the product has a pH level of 7 or over and it is a non-acidic product. The cuticle opens up when an alkaline substance is applied to it. This is what allows hair colorant to penetrate the cortex. There, it reacts with the hairs pigmentation to produce the color change.