Abstract: The disclosed invention includes methods to employ wearable biosensing devices to accomplish the following: 1) screen for the presence of a disease or infection, including pre-symptomatic detection, and determination of the type (e.g., viral, bacterial, or fungal) of disease or infection present; 2) confirm the antigen and monitor the progress of an active infection; and 3) monitor the efficacy of a treatment program for a disease or infection. Such methods rely on the detection, in sweat or other biofluids, of proteins, nucleotides, DNA polymerases, proteases, group-specific antigens, antibodies, cytokines, or other molecules, that are produced by the body as part of the innate or adaptive immune responses to an infectious agent, or the infectious agent itself, its products, or derivatives. Some embodiments comprise a method of using such a biosensing device as a biosentinel against biological threats.