Changing Socioeconomic Indicators of Human Plague, New Mexico, USA

Anna M. Schotthoefer¹

, Rebecca J. Eisen, Kiersten J. Kugeler, Paul Ettestad, Pamela J. Reynolds, Ted Brown, Russell E. Enscore, James Cheek, Rudy Bueno, Joseph Targhetta, John A. Montenieri, and Kenneth L. Gage

Author affiliations: Centers for Disease Control and Prevention, Fort Collins, Colorado, USA (A.M. Schotthoefer, R.J. Eisen, K.J. Kugeler, R.E. Enscore, J.A. Montenieri, K.L. Gage); New Mexico Department of Health, Santa Fe, New Mexico, USA (P. Ettestad, P.J. Reynolds [retired]); New Mexico Environment Department, Santa Fe (T. Brown [retired]); Indian Health Services, Albuquerque, New Mexico, USA (J. Cheek); Harris County Public Health and Environmental Services, Houston, Texas, USA (R. Bueno, Jr.); and City of Albuquerque Division of Environmental Health, Albuquerque (J. Targhetta)

Abstract

Socioeconomic indicators associated with temporal changes in the distribution of human plague cases in New Mexico were investigated for 1976–2007. In the 1980s, cases were more likely in census block groups with poor housing conditions, but by the 2000s, cases were associated with affluent areas concentrated in the Santa Fe–Albuquerque region.

Plague is a severe zoonotic disease caused by Yersinia pestis. An average of 11 cases per year have occurred in the United States (range 1–40 cases) since 1976 (1); most cases in recent decades have been found in New Mexico (2,3). The pathogen cycles between rodents and fleas, and humans most frequently become infected through flea bites (4). Living near habitats that support the sylvatic cycle is a major risk factor associated with human disease in New Mexico (2,5,6). However, even in areas defined as high risk on the basis of environmental characteristics (6), plague is rare, and the area defined as highly suitable for plague represents a large geographic region (≈52,626 km²).

Poor socioeconomic status has been anecdotally associated with human plague cases, but this factor has rarely been investigated quantitatively in the United States, and such information has not been systematically collected for cases of Y. pestis infection. Identifying human socioeconomic or behavioral risk factors may enable a more refined definition of the highest risk populations for more targeted control efforts. To evaluate possible associations between socioeconomic factors and plague risk, we used US Census Bureau decennial data to compare census block groups (CBGs) in which human plague cases occurred and did not occur in New Mexico during 1976–2007.