please help me answer the following:

CASE 6 20. A panel of government agents is tasked with reevaluating the criteria in order to definitively diagnose a patient with Ebola virus infection. The panel decides to raise the serology criteria from an antibody titer of 64 to an antibody titer of 128. How will this influence the incidence and prevalence of Ebola diagnoses in the future? CASE 7 21. A recent study has identified a novel compound in the blood that can better predict the risk of stroke. A screening test for this novel compound, X10, was developed and tested in a population of patients who recently had a stroke. After testing it was determined that circulating X10 levels greater than 100 nM indicated a high risk stroke patient. After using the screening test in the general population it was found that this X10 concentration produced too many false-positive results, therefore the screening test value for X10 levels was increased to 500 nM in order to pe considered at risk for a stroke. How would this change affect the PPV and NPV? How would this change affect the sensitivity and specificity