An article in Nature Medicine available online on August 2 reports a new strain of HIV found in a Cameroonian woman. This new strain bears no resemblance to the current strains infecting humans or chimpanzees, but appears to be closely related to the virus found in gorillas.

In an interview with BBC, co-author of the article Dr. David Robertson of the University of Manchester assures the public, “There’s no reason to believe this virus will present any new problems, as it were, that we don’t already face.” Although it is a new type of HIV strain, he thinks existing drugs will remain effective.

The gorilla virus was discovered in 2006, but this report is the first account of a similar virus causing infection in humans. Researchers indicate that the most likely explanation is gorilla-to-human transmission, but it is possible that the new strain came from chimpanzees and then spread to gorillas. Currently, the virus mainly responsible for human infections originated from chimpanzees.

The new strain, called RBF168, was isolated from a 62-year-old Cameroonian woman who recently had moved to Paris. She is the only known person to be infected with the new strain, but researchers believe this case “does not seem to be an isolated incident.”

The woman previously lived near the capital of Cameroon and had not come into contact with gorillas or eaten bush meat, the probable source of HIV in humans. This suggests that she caught the virus from someone else. It is therefore unknown how many other people are carrying the gorilla strain.

Professor Paul Sharp of the University of Edinburgh raises the possibility that the new strain can evade detection by conventional tests used to determine particular HIV strains. In an interview with BBC, he said the new strain could be spreading within the human population without notice.

Sharp does not mean that individuals are unaware of their HIV infection; rather, that they do not know the specific viral strain they carry. Like RBF168, new strains should be treatable with the currently available antiretroviral drugs, but it is more difficult to track their transmission between people and across regions.

Additionally, tests to determine the viral load in patients with new strains may not work, as was the case in the Cameroonian woman. As a result, doctors may find it more difficult to provide optimal treatment for HIV-infected individuals.

Researchers conclude that their finding “highlights the continuing need to watch closely for the emergence of new HIV variants.”

For more information, see the study in Nature Medicine.