In 1998, a woman in Cameroon was the first to be identified with the “group-N” strain of human immunodeficiency virus (HIV).  Since then, this extremely rare strain has only been confirmed in 12 other individuals within Cameroon.

A recent report in The Lancet, published November 26, 2011, provides new evidence that this rare group-N strain of HIV has likely moved beyond the borders of Cameroon. The report describes a 57-year old man admitted to a Paris hospital in January 2011. Initial tests to determine the strain of HIV infection present proved inconclusive. Further testing showed “clear reactivity against group-N-specific antigens.” The man had recently returned from the African nation of Togo, and based on his sexual history had likely acquired the infection while there.

This is the first evidence of group-N HIV occurring outside of Cameroon. The Lancet publication states that this finding is of particular importance due to the severe clinical manifestations and quick progression to acquired immune deficiency syndrome (AIDS) associated with group-N HIV. The report concludes that increased epidemiologic monitoring of group-N is rapidly needed now that it is likely circulating beyond the borders of Cameroon.

In comparison to the three other sub-types of HIV-1, group-N infection appears to be closely related to Simian Immunodeficiency Virus (SIV) found in wild chimpanzees. This suggests that the strain may have been introduced to humans through the handling of SIV-infected bushmeat. The other groups of HIV include group-M (the most common strain with more than 90 percent of HIV-1 infections belonging to this group), group-O (primarily found in West Africa), and group-P (discovered in 2009). While groups M and N are most similar to SIV found in chimpanzees, groups -O and -P have been linked to SIV in wild gorillas.

Another viral family also exists: HIV-2. It is thought that HIV-2 was transmitted to humans from the sooty mangabey (an Old World monkey). Infection with HIV-2 is often milder and less likely to cause AIDS.

With World AIDS Day on December 1st, 2011 it is hoped that the tremendous progress made in fighting the AIDS pandemic over the past 30 years will continue despite a recent announcement by the Global Fund to Fight AIDS of funding cuts


Constance Delaugerre, Fabienne De Oliveira, Caroline Lascoux-Combe, Jean-Christophe Plantier, François Simon, HIV-1 group N: travelling beyond Cameroon, The Lancet, Volume 378, Issue 9806, 26 November-2 December 2011, Page 1894, ISSN 0140-6736, 10.1016/S0140-6736(11)61457-8.

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