there are a few techniques being found such as :
1. Enzyme linked immunosorbent assay or ELISA which detects the presence of the virus, antigen or antibody in a sample.
2. Polymerase chain reaction or PCR which generates copies of a particular section of a single DNA strand into thousands. From these strands, we can find if they are vectors for the bacteria or have any expressions of them.
* Another method is by examining RNA within circulating immune cells and at times, detecting the diseases through Hemorrhagic fevers. But even with these methods, the first preference in detecting diseases is always given to distinguishing the symptoms and signs of the patients.
Hope this helps !