Question

why are infectious and noninfectious diseases?

Answer 1

A non-communicable disease (NCD) is a medical condition or disease that is not caused by infectious agents (non-infectious or non-transmissible). NCDs can refer to chronic diseases which last for long periods of time and progress slowly. ... NCDs are the leading cause of death globally.

An infectious disease is a disease caused by a microorganism and therefore potentially infinitely transferable to new individuals. ... A communicable disease on the other hand is an infectious disease that is contagious and which can be transmitted from one source to another by infectious bacteria or viral organisms.

Hope this helped!!!

Answer 2

An infectious disease takes hold of the body after action from an external agent. That agent could be viral (influenza B is a common one) or bacterial (salmonella, for example). There are also, as my mom used to say, fungus-among-us: ringworm is one that you can get very easily if you let others wear your eyeglasses. Parasites are pretty rare, but they're out there, too - just ask someone who has had Montezuma's Revenge, AKA amoebic dysentery.

Now, other diseases? Well, those are, for one, congenital conditions. They are acquired through a combination of parental strands of DNA. Other diseases such as cancer are based on heritable factors (different levels of melanin in the skin, for instance)  and environmental factors (hey, I have fair skin, hazel eyes, and red hair! Derp, I should probably not have tanned in grad school!). Other cancers have more behavioral causes, as scientists have very recently found a link between oral sex and throat cancer. Obviously, more non-infectious diseases exist, with causation linked to varying bouquets of behavior, environment, and genetics.

Interestingly enough, the discussion isn't as cut and dried as all that. They do interact. The presence of an infectious disease can lead to complications and, in the case of HPV and cervical cancer, be a marker of sorts for a non-infectious disease.

Hoping this helps!