Where I live, microbiologists work the diagnosis by examining stool through a microscope. Nowadays, though, doctors are lazy and just prescribe antiparasitaries without a diagnosis.
I was taught to suspect worms only in children and immunicompromised adults. And I never found the exception.
Depends on where you live. Parasites are utterly endemic in areas as close as a 30 minutes drive away from me. They are commonly found in patients of all ages, including otherwise normal functioning adults.
Depending on the epidemiology, testing a population is a waste of time and money. They have a very high chance of having the disease and a very high chance of reinfection even after treatment. So what happens is those patients come in every once in a while and they straight up ask for their periodic albendazole dose. And then they go back to their homes and they drink the exact same water and eat the exact same food.
I was taught to suspect worms only in children and immunicompromised adults. And I never found the exception.