Prevalence and anatomical evidence of Treponemal Infection in the Cobb Collection
By Nicholas Guthrie, Department of Biology, Howard University '16
Understanding the health of our ancestors can give us a viewpoint to understand present-day health conditions. The relationship of African American (AA) ancestry to infectious disease status has not been extensively studied. This study aims to characterize AA health by osteologically investigating the microbial effects of Treponema palladium (TP) bacteria on AAs who died in the greater DC metropolitan area from 1930 to 1969. The gram-negative, spiral shaped bacteria has four pathogenic subspecies; pallidum, pertenue, endemicum, and carateum, causing syphilis, yaws, endemic syphilis, and pinta, respectively. To confirm TP infection, we will use the Cobb Collection autopsy and clinical records in conjunction with scientific methods of microscopic analysis, microbial analysis, and various imaging techniques. Our expected results will yield better understanding of the pathology of TP and its contribution to AA morbidity and mortality during the era of overt racial segregation to the present day.
The W. Montague Cobb Research Laboratory is a rare resource for research on a unique human skeletal and bioarchaeological collection. The Cobb Collection is named after the first African American biological anthropologist and renowned Chair of Howard University’s Anatomy Department, Dr. William Montague Cobb. His research aimed to create a less racialized perspective on human life and showed the impact race could have on the heath of a person, showing that racism in America had an impact on the health and livelihood of African Americans. (Kamei, 2015) The Cobb collection contains approximately 699 de-fleshed human cadavers that were donated and collected for scientific purposes during the majority of the 20th century, and is unique in that it is the only skeletal collection residing at a historically black university. The Cobb Collection has undergone very little research and lends itself to novel insights about the lives and deaths of Americans living in the Washington, D.C. area. This affords this research a unique opportunity to become a reference on African Americans from the late 19th to mid- 20th Century. Approximately 83% of the Cobb Collection is African American and contains records with significant clinical and autopsy data including age, sex, place of death, cause(s) of death, and morbidity (Cross, 2015).
Health disparities for African Americans include differences in rates of cardiovascular diseases, diabetes, periodontitis and life expectancy relative to whites. In addition, populations living in poverty also exhibit health issues including asthma attacks and obesity. Since a greater percent of African-descendant people continue to live below the poverty line, a duality of risk factors exist for this population. Furthermore, previous research hints at differences in health between African-descendant people in Africa and the United States, suggesting that variation in environment, such as slavery and poverty, affects general health. (Gomez, 2015)
Treponemes (TP) are helically coiled, corkscrew-shaped cell with a double membrane system. The spirochete has two flagella that originate at both ends of the organism and point inward along its length, and are contained in the periplasmic space between the inner and outer membranes, which enable motility. The pathogenic treponemes’ classification is based primarily upon the clinical manifestations of the respective diseases they cause: Treponema pallidum subsp. pallidum is the causative agent of venereal syphilis; T pallidum subsp. Pertenue causes yaws; T pallidum subsp. endemicum causes endemic syphilis; and T carateum is associated with pinta. -These microbes are generally transmitted by close non-venereal contact, with the exception of venereal syphilis. DNA hybridization shows high genetic relation between the species, but overall understanding of the pathogenesis of human treponematoses is limited. The inability to grow these spirochetes in vitro and limited viability in vivo requires expensive and difficult continual propagation in laboratory animals. Also, their fragile cellular ultrastructure permits only limited mechanical manipulation of the pathogen, in order to preserve its integrity and viability (Giazani, 2014).
Diagnosis of treponemal disease relies heavily on its clinical manifestation. The patient's symptoms and signs, in combination with knowledge of the epidemiological context of human treponematoses aid in a positive diagnosis. Treponemal disease manifests in three stages: primary, secondary, and tertiary. In all stages, tissue damage is caused by both localized and systemic inflammation. Primary infection produces mild, non-diagnostic lesions, secondary stage infection adds osteitis, or inflammation of the inner structures of bone (though it can heal spontaneously), and tertiary infection shows distinctive skeletal lesions and osteomyelitis, an infection originating in the marrow. Neurological affects do occur but symptoms may not become apparent until years after infection, though infection of the central nervous system occurs relatively early. In the laboratory, the available diagnostic tools for detection are direct detection of treponemes in biological specimens, through including molecular assays and serological tests is desirable (Harper, 2011).
Methods and Results
In order to screen the Cobb Collection for TP, the database of medical records was evaluated for TP cause of death. Three members of the collection, CC18, CC22, CC109, were then inspected for TP bone lesions using methods from Rothchild et al (1994) All surfaces of skeletal remains were visually examined to identify all occurrences of bone alterations throughout each skeleton and variation from normal smooth cortical surfaces was noted. Treponemal disease was specifically recognized on the basis of periosteal reaction and osteitis.
Figure 1. Rothchild Experiment showing periosteal reaction
Figure 2. CC18 showing periosteal reaction
Conclusions and Future Directions
Through screening, TP infection was visually confirmed in the 3 subjects. While a sample size of 3 does not allow for many conclusions to be drawn about the health conditions of the time period, additional screening of the Cobb Collections can be conducted in the future. The TP infection lesions are not unique to TP infection. For example, Mycobacterium tuberculosis, the causative agent of tuberculosis, is shown to cause bone lesions in late stages of infection (Haas, 2000). Therefore, CC members with similar bone degradation should be screened for TP infection using DNA extraction and molecular diagnosis.
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