AIDS is generally diagnosed by a blood or saliva test that measures the T-cells in a person's body. If the count drops below 200/mm3, the immune system is seriously damaged and unable to fight infections properly. A diagnosis of AIDS also occurs if a person gets one of 26 opportunistic infections, which are conditions common in advanced HIV patients, but rarely found in people with intact immune systems. Most people who die of AIDS do so from one of these infections. But while there is no cure for the disease, the introduction of highly active antiretroviral therapy has caused the number of AIDS-related deaths to decrease significantly