Objective By studying the serum ADA activities of people infected with HIV, the paper aims to study the applied value of clinical diagnosis and therapeutic effects. Methods Taking 13 cases of drug users, 16 cases of STD patients and 7 cases of AIDS patients as samples, the paper applies automatic operation to detect the serum ADA activities. Results Before being detected to be HIV antibody - positive, the serum ADA activities in HIV infected patients increase. However, when HIV antibodies convert to be positive, the serum ADA activities reach the highest value after which the serum ADA activit...