Mon, May 20, 2013 1:45 PM EDT

The Indian Health Service released a new report recently showing that HIV infections are on the rise in  the Navajo nation. The tally of new cases from last year represents the highest annual number ever recorded among the tribe by the health agency.

The federal report released last month found that there were 47 new diagnoses of human immunodeficiency virus on the reservation in 2012, up 20 percent from 2011. Since 1999, new H.I.V. cases among Navajo are up nearly fivefold, the report found.

According to the report, men who have sex with men accounted for nearly half of the new cases.