Whether a patient is in the early or late stages of HIV can be determined by the patient’s clinical symptoms and blood tests. In the early stages of HIV, the patient will not have obvious clinical symptoms and will not have secondary infections. A blood test of the patient’s immune function will show that the CD4+ T-lymphocyte count is at a relatively high level and the viral load is not particularly high. If in advanced stages, patients can develop a variety of secondary infections due to low immune function, such as pneumonia with Pneumocystis carinii, meningitis with Cryptococcus, esophagitis with Candida albicans, and so on. The viral load will often be very high and the CD4+ T-lymphocyte count will be very low, usually less than 200/mm3.