Native Americans on the New Mexico Navajo reservation have experienced a sharp uptick in HIV cases, particularly during the past five years, The New York Times reports. A report out of the federal Indian Health Service found that, between 1999 and 2012, the incidence rate for new HIV diagnoses among the Navajo increased almost five-fold, and there was a nearly three-fold jump between 2007 and 2012.

The actual numbers are small—10 cases were diagnosed in 1999, 16 in 2007 and 47 in 2012, for example—but health workers are particularly concerned because Navajo appear to be transmitting HIV among themselves instead of mostly traveling into cities and acquiring the virus there. Adding to the concern is the fact that survival rates for Native Americans following an AIDS diagnosis are lower than for any other racial group. Contributing factors might include lower rates of routine testing for HIV among Native Americans and higher rates of other health conditions such as diabetes or alcoholism.

The increase in HIV diagnoses may be partly a result of cases being detected earlier, as a result of increased routine screening and programs to educate about the virus.

Nearly half of the new diagnoses were among men who have sex with men.

To download a copy of the report, click here.

To read the New York Times story, click here.