Patients with AIDS are usually routinely tested for antibodies, antigens, routine blood tests, macrobiochemistry, and immunology. In addition, depending on whether the patient has opportunistic infections, additional tests are needed, such as x-rays to understand the condition of the lungs, and sputum and bronchial secretions or lung biopsy. Some patients who suspect Cryptosporidium infection also need a stool smear, and patients with cryptococcal meningitis need to have their cerebrospinal fluid examined. There are also some patients who need to be examined for toxoplasma, hepatitis virus, cytomegalovirus infection, etc., to check for antigens or antibodies. Some patients with infections need blood or secretion cultures, and if lymphoma or Kaposi’s sarcoma is suspected, a tissue biopsy is also needed.