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Biosecurity BriefingStudy Examines Role of Human Migration Patterns in Re-Emergence of Tuberculosis in BeijingBy Amesh Adalja, MD, September 8, 2008 The September 2008 issue of Emerging Infectious Diseases (EID) includes an article regarding tuberculosis cases in Beijing, drawing attention to the contribution of migration patterns to the total disease burden in the city. Reforms in governance, beginning in 1980, permitted people to move from their native locales to other areas—chiefly farmers moving to cities in search of work. Because the highest prevalence of TB lies within the rural region, this population has the potential to spread the disease from rural areas to Beijing. Migrants presently number in the millions and comprise 1/3 of the Beijing population. Compounding this fact is that the migrant population has less access to public health services; additionally, migrants are more likely to be employed at lower income levels, which limits coverage by social medical insurance.1 Using geographic information system techniques that incorporate migrant/non-migrant population densities and tuberculosis case locations, the authors conducted a mathematical/spatial analysis of tuberculosis cases in Beijing from 2000–2006. For the purposes of the study China was divided into several geographic zones. Of the migrants studied during this time, 61.6% were male, 16.8% came from the western zones, 40.5% came from the eastern zone, 41.9% came from the middle zones, and 0.8% from Tianjin and Shanghai.1 The study included 15,078 cases of TB among residents and 7,948 cases among migrants. Results revealed that tuberculosis cases were distributed randomly among permanent residents but were clustered in migrant populations. Five districts within Beijing were discovered as “hot spots” for tuberculosis prevalence—all but one of which was associated with migrant populations. Additionally, the areas identified as “hot spots” were central (as opposed to suburban) districts, pointing to the role of high population density in the spread of TB. The authors attribute their results to migrant populations having decreased access to health care and unique working conditions as well as the fact that they originate from areas of China with high TB prevalence, rendering them more likely to harbor the infection. The authors advocated for stronger TB control measures that incorporate the migrant population and raise the concern that businesspersons, travelers, and public transportation may also play a role in the transmission of TB.1 References
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