When you get your blood checked for a certain disease will they discover other ones, too?

say for example, they send your blood to a laboratory to check if you have rabies, will they find HIV? so to say, you get one HIV testing for free? is this reliable or is there a possibility that they may overlook something if they're not explicitly searching for it?

Usually there has to be an order from a physician to check for certain things. But some doctors order tests like hepatitis b, c and hiv if the patient is pregnant or seems to be at high risk for infection, If you feel that you need to be tested contact a local health department. the price is not as expensive as private doctor office and of course all test results will be confidential Good Luck

Absolutely not. The problem is quite the other direction. Labs have to be strong armed into doing testing in depth because it costs money. They are always looking for reasons to weasel out of doing the work by pairing down groups of tests.