Between 1995 and 1998, less than 4 percent of the patients caught resistant virus. In 1999 and 2000, this rose to 14 percent. Six percent of these had a virus that was resistant to two drugs. Most of those who catch HIV never realize it until years later. However, patients occasionally realize it soon after infection because they get temporary flulike symptoms.
Some doctors recommend immediate drug treatment for such patients.
In these cases, Little said, doctors should check their patients' viruses to see if they are resistant to any drugs before starting therapy. Doctors believe that without treatment, patients' drug-resistant virus eventually evolves back to the nonresistant form. Still, a record of the resistant virus is stored in patients' immune systems, and it can reemerge once treatment starts. The growing spread of resistant virus is tremendously important in the ability to treat people effectively, said Dr. Douglas Richman, another member of Little's team. Another study, conducted by Dr. Hillard Weinstock of the Centers for Disease Control and Prevention in Atlanta, raises the possibility that the level of resistant virus varies greatly among different risk groups.