(CNN) -- French researchers have identified a new human immunodeficiency virus, the first derived from gorillas, a report said Monday. A new virus is difficult to detect by tests because it is not closely related to the other three HIV variants. The three previous HIV variants came from chimpanzees. The new findings indicate that gorillas, in addition to chimpanzees, are likely sources of HIV, the researchers concluded in a report published in the weekly Nature Medicine journal. The new virus, called RBF 168, was detected in a 62-year-old woman who moved to Paris, France, from the western Africa nation of Cameroon, the report says. She tested positive for HIV in 2004, and researchers led by Jean-Christophe Plantier identified the virus as being closely related to a recently discovered simian immunodeficiency virus (SIV).
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Strain is the first known to be derived from gorillas
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62-year-old woman who moved to Paris from Cameroon found to have RBF 168
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Likely explanation for emergence of new virus is gorilla-to-human transmission
"The human prevalence of this new lineage remains to be determined," the report says, adding that "it could be circulating unnoticed in @placeholder or elsewhere."