Background:
National STD rates among American Indians and Alaska Natives (AI/AN) are 2 to 6 times higher than rates for whites. Because AI/AN are diverse (over 560 federally recognized tribes in 35 states), STD rates likely vary by region, yet these data are not readily available.

Objective:
Describe STD rates and trends among AI/AN by region.

Method:
During 1998-2004, we calculated crude annualized rates for chlamydia (CT), gonorrhea (GC), and primary and secondary syphilis (P&S) for AI/AN living in counties on or near reservations in 6 geographic regions: East (E), Northern Plains (NP), Southern Plains (SP), Southwest (SW), Pacific Coast (PC), and Alaska (AK). Numerators were based on county-level STD cases reported to CDC, and denominators were based on census population estimates. We compared rates with those in the general US population (USG). Rates are expressed as per 100,000 population.

Result:
In 2004, the overall AI/AN CT rate (808.4) was 2.5 times higher than the USG rate (319.6). This disparity resulted primarily from high CT rates in AK (1,600) and NP (1,391.1). For GC, the overall AI/AN and USG rates were similar (119.9 and 112.4, respectively). GC rates were highest in AK (263.2) compared to other regions. For P&S, overall AI/AN and USG rates were also similar (3.4 and 2.7, respectively). Except for SW, which had a P&S rate of 10.9, all other regional rates were below that of USG; 4 regions (E, NP, SP, AK) reported no P&S cases in 2004. Since 1998, though some regional rates have increased substantially, overall AI/AN rates have remained stable (GC) or increased modestly (CT and P&S).

Conclusion:
AI/AN STD rates vary considerably by region. Further studies are necessary to identify determinants for these differences.

Implications:
Regional data should be used to guide local STD prevention and control efforts in Indian Country.