HIV Aids
A HIV-positive patient undergoes a blood test. Reuters

A 57-year-old man living in France, who recently traveled to Togo, has been diagnosed with a rare type of HIV-infection -- called group N. This is the first reported case of the infection outside Cameroon.

The infection is more similar to the virus type found in chimpanzees than to the types diagnosed in humans, said the case study published in the Lancet medical journal.

Most types of HIV in humans are either group M or, less commonly, group O.

The first case of group N was diagnosed in a woman living in Cameroon in 1998, and since then only 12 cases, including two couples infected by the same strains, have been identified, all in Cameroon.

A fourth group, designated as P, was identified in a Cameroonian woman living Paris in 2009.

In this reported case, the 57-year-old man attended an emergency unit in Hôpital Saint-Louis with fever, rash, swollen lymph glands, and genital ulceration, eight days after returning from Togo.

He reported sexual contact with a Togolese partner, and HIV primary infection is suspected.

Once the HIV was detected, the medical supervisors say they were surprised to see that the virus did not match with standard types, reports the medical journal.

The study says that this case of primary HIV-N infection is particularly important because of severe clinical manifestations and early decline in CD4 cell count.

A five-drug antiretroviral combination showed good initial efficacy, but longer-term immunological and virological follow-up is needed.

"This case of HIV-1 group-N primary infection indicates that this rare group is now circulating outside Cameroon, which emphasises the need for rigorous HIV epidemiological monitoring," experts have said in the case study.