Provided are methods of detecting a marker for active tuberculosis, and a portable device for carrying out a method of detecting a marker for active tuberculosis. Also provided is a system for carrying out a method of detecting a marker for active tuberculosis, a method for pre-treating a sample stream from a human or animal suspected of having active tuberculosis, a system for pre-treating a sample stream from a human or animal suspected of having active tuberculosis and kits for performing said methods.