Scientists have confirmed the existence of an additional strain of HIV that has existed for decades, according to findings published Wednesday in the journal of acquired immune deficiency syndrome.
The strain is not new; rather, what is changing is the technology used to test the virus.
"The subtype has existed for as long as all other strains. We just didn't recognize it as an official subtype so far, "says Mary Rogers, author of the new study and chief infectious disease research scientist at Abbott Laboratories.
HIV, or human immunodeficiency virus, is the virus that causes AIDS if not treated early and appropriately. Important news and stories deliver in the mornings on weekdays.
The Centers for Disease Control and Prevention estimates that in 201
The newly recognized strain is classified as subtype L in the HIV-1 family M group. "M" stands for "major" because it is responsible for more than 90 percent of HIV infections worldwide.
Because this family of viruses is so widespread, experts believe that drugs already used to control HIV could also work for subtype L. There is no reason to believe that this subtype is more dangerous or virulent from every other strain of HIV.
"I would expect him to respond to treatment the same way other strains do," Rogers told NBC News. "I don't think there is cause for concern."
There are 10 different subtypes in the M group. Subtype L was first identified in 1983, then again seen in 1990, and in the Democratic Republic of the Congo. It opened for the third time in 2001, also in the Congo.
But it took so long to refine the technology used to sequence the subtypes. Scientists are now able to test the entire genome to confirm that the samples were part of the same subtype.
This is important because it helps scientists discover precisely the wide variety of HIV strains circulating globally, Rogers said. This, in turn, helps prevent epidemics that could arise from viruses that may have mutated.
"The whole point of what we do," Rogers said, "is to make people feel safe."
Follow NBC HEALTH on Twitter & Facebook.