Racial differences in disease susceptibilities: Intestinal worm infections in the early twentieth-century American South

While the use of ancestry, ethnicity or race in contemporary medical and scientific research is controversial and the subject of debate in the United States, a hypothesis of 'racial' differentials in susceptibilities to disease has utility in the American historical context. This study employs a dataset of 542 residents of Marion County, South Carolina, collected in 1922 by medical teams to investigate the prevalence of hookworm in the American South. An examination of data for Marion County is useful because it is representative of counties in the rural agricultural South where hookworm was endemic throughout at least the early twentieth century. The results of a multivariate regression indicate a large, statistically significant difference in hookworm infection between African-Americans (blacks) and European-Americans (whites). Controlling for other demographic factors, an otherwise average white was 2.8 times more likely to be hookworm infected compared to an otherwise average black in Marion County. The predicted probability of testing positive for hookworm was 56.1 per cent for an average white and 20.3 per cent for an average black. The findings are consistent with other evidence on racial differences in hookworm infection, and have implications for understanding important historical issues concerning economic development in the American South. They also suggest that historical datasets contain important information when ancestry, ethnicity or race indentify people whose heritage is predominately from specific disease ecologies.