An infectious disease screening system (1) for screening for infectious diseases, such as COVID-19 disease. The system comprises an ultrasonic transducer (49) for generating ultrasonic waves to lyse cells in a biological sample. The system (1) comprises a controller which controls the ultrasonic transducer (49) to oscillate at an optimum frequency for cell lysis, a PCR apparatus (16) which receives and amplifies the DNA from the sample; and a detection apparatus (70) which detects the presence of an infectious disease in the amplified DNA and provides an output which is indicative of whether or not the detection arrangement (70) detects the presence of an infectious disease in the amplified DNA.