Shigellosis in New Mexico, 2004-2008

Since 2004, New Mexico (NM) has been collecting epidemiologic and laboratory information on confirmed cases of Shigella through its participation in the CDC's Emerging Infections Program. Between 2004 and 2008, there were 708 laboratory-confirmed cases of shigellosis in NM, with the highest number of cases (172) reported in 2006, with a rate of 8.5 per 100, 000. Commonly reported serotypes included S. sonnei (66%), S. flexneri (22%), S. boydii (2.4%), and S. dysenteriac (0.4%), consistent with nationally reported serotype percentages. The highest percentage of cases each year was seen in the age group 5-19 (30%) and predominantly in females (53%). Of the 419 (59%) cases with known ethnicity, 288 (41%) were Hispanic, and 130 (18%) were Non-Hispanic. Of the 502 (71%) cases with known race, 347 (49%) were white, 147 (21%) were Native American, 5 (1%) were Asian/Pacific Islander and <1% were black or multi-race, indicating an over-representation of Native Americans compared to NM's population. Analysis of data from the U.S. National Notifiable Diseases Surveillance System indicated increased risks for certain foodborne and waterborne diseases in U.S. counties that share a border with Mexico. Four of NM's southernmost counties share a border with Mexico, and this unique region represented 33% of all shigellosis cases reported between 2004 and 2008, while representing only 15% of New Mexico's total population. Border county rates ranged from 6.8 per 100,000 in 2007 to 17.0 per 100,000 in 2006. Continued laboratory-based surveillance of Shigella will help understand these regional variations in incidence.