What infectious diseases won't show up on blood and urine tests?

dagespath - Yes, there are many infectious diseases that won't show up on blood and urine tests such as tuberculosis, strep throat, and pinworms. Then there are many that could show up but would be extremely expensive to test for and so are rarely considered, such as virus cultures for several epidemic hemorrhagic fevers as lassa and ebola. Yet, many simple infectious diseases can be easily and rapidly tested and diagnosed such as malaria, herpes, and HIV.

As for Candida, also known as Monilia or thrush (mouth), it is an extraordinarily common fungus found on just about every person's skin, especially the mouth and groin area. It rarely causes serious infection unless it breaks into the body. Doctor's can make an easy diagnosis, but know its presence is often not connected with disease. In the intestines, a few Candida are normally present, causing no illness, as they are held in check by other bacteria. If these "other" bacteria are knocked out by antibiotics, then the Candida can suddenly grow and do body harm, even enter the blood stream.

It's going to show as an opiate, which is commonly checked for in most drug tests. More extensive testing would need to be conducted in order to determine the specific type of opiate. Depending on the purpose for the drug test i.e. pre-employment you'd be required to show documentation of a prescription for an opiate. If you have a prescription, your best avenue is to inform the entity that is requiring the drug test before hand as to avoid any confusion.