If you never mind if my answer in the usefulness of lateral flow assay in diagnosis of infectious diseases .............. The lateral flow assays are characterized by fast results and suitability for application in field but the main issue is the sensitivity and specificity ... a lot of research article compare between available diagnostic assays and lateral flow assay state that it is not highly sensitive in comparison to PCR for example. another issue is specificity, it  based in using of antibodies in detection of causative agent, to ensure good specificity, you can not use polyclonal antibodies, you should use special monoclonal antibodies which add production of monoclonal antibodies as an obstacle in assay validation. you can find commercially available monoclonal antibodies but still need a lot of validation for assay validation. Therefore, most of diagnostic laboratories do not depend a lot of lateral flow assays in diagnosis of infectious diseases. for infectious diseases agent detection validated Real time PCR is the most used assays as it is characterized by high sensitivity, in comparison to other assays, and high specificty due to used of taqman probe but it need well trained expert person in validation of assays for used as routine diagnostic tests. and good luck