Skeletal collections can provide fascinating and important information about the origins and development of disease.
“Knowledge of diseases in the past can inform health practices of today,” said STIAS fellow Maryna Steyn, Head of the Human Variation and Identification Research Unit at the University of the Witwatersrand. “They also serve as an important reminder that humans, pathogens and diseases are always evolving.”
Steyn’s STIAS project is about the bioarchaeology of South Africa – the study of human remains in an archaeological context. This research aims to synthesise the results of past and current studies of archaeological human remains in South Africa, from the start of the Holocene (± 10 000 BP which includes the Stone and Iron Ages) up to colonial contact.
For her STIAS seminar, she focused on her group’s work on tuberculosis.
TB and mining
The emergence and spread of TB in South Africa is closely associated with industrialisation, with no conclusive evidence of its presence in South Africa before colonial contact. “TB and the migrant labour systems in the mines are closely linked and the consequences are still felt today – TB is still the most common cause of natural death and of HIV-related deaths in South Africa.”
Sketching the history, Steyn pointed out that industrialisation took off after the discovery of diamonds and gold. In 1870 diamonds were discovered in Kimberley and in 1886 the main gold reef in the Witwatersrand was discovered and, by the mid-1890s, had become the world’s largest mining district. This changed the economy from primarily agriculture to mineral wealth. People flocked to these areas. Once the mining went deep level, requiring more workers, there was uncontrolled population expansion. By the end of the 19th century there were about 41 000 people in Kimberley and 100 000 in the Witwatersrand.”
“The mining industry shaped subsequent labour practices in South Africa.”
These areas (especially Kimberley) were remote with limited infrastructure, so miners were housed in compounds. These were initially open but as security became an increasing concern the pass system was introduced and living conditions became more restrictive. Migrant labour came from all over southern Africa with about half from neighbouring countries. Between 1904 and 1910 the British also brought in Chinese labourers.
“All lived in dismal conditions where disease, trauma and malnutrition were rampant,” said Steyn. There was a high death rate due to pneumonia, intestinal infections, syphilis and scurvy. Human life had little value. It was estimated that white miners only survived about five years – the rate for black miners would have been much worse.”
She described TB as a virgin-soil disease – brought in by the European and Chinese miners and spread to other regions by oscillating migration – “sick miners were often sent home to die thus often infecting their families”.
“TB progressed rapidly in tandem with mining and specifically with the development of closed compounds,” she added.
Steyn and her colleagues have explored evidence of TB in skeletons of early miners around Kimberley and the Witwatersrand. They have also looked at changes in skeletal manifestations of TB throughout the 20th century. The main source is the Raymond A. Dart collection housed at the University of the Witwatersrand – the largest human skeletal collection in South Africa, which includes approximately 3000 documented skeletons. “This includes over 500 skeletons known to have had TB, with the first dating from the 1920s,” said Steyn. They also included samples from the Western Cape (from the Universities of Cape Town and Stellenbosch).
Changing patterns
The work involves identifying skeletal lesions associated with TB. Steyn explained that although TB lesions can be found in any part of the skeleton, they are most common in the vertebral column – specifically the first lumbar vertebrae, followed by the ribs. Cranial lesions are reported to be rare, although this was found not to be the case in South Africa.
Major developments in the field of TB include the introduction of the first antibiotic to treat TB in 1948 – streptomycin; and, the advent of the HIV pandemic from the mid-1980s with high coinfection rates, as well as increasing multi-drug resistant TB. The group has therefore looked at skeletal remains from these periods to try to understand the impact of these developments.
The study found an overall increase in TB skeletal lesions associated with antibiotic introduction and post 1985.
“Skeletal indicators of TB in pre- and post-antibiotic individuals, as well as in the post-HIV era, suggest that patterns of skeletal involvement are changing,” said Steyn. “An increase in skeletal involvement in individuals dying of this disease was noted, probably as a result of people living longer due to long-term antibiotic treatment and thus having more time to develop skeletal lesions.”
“With antibiotic use for TB people live longer, but they may have had recurring disease. Their TB may have become dormant due to antibiotics then be reactivated due to various causes. So, although they may have lived longer, they may have suffered more.”
“HIV also changed the disease expression with changing patterns of lesions.”
“Also, surprisingly, there was a high frequency of cranial lesions which hint at TB meningitis.”
“Some differences in patterns of skeletal involvement were noted between skeletal samples from Gauteng and the Western Cape,” she added.
But skeletal TB lesions are difficult to distinguish from those caused by other diseases. Another study therefore looked at the sensitivity and specificity of various skeletal lesions to indicate TB and suggests that even the most pathognomonic of these lesions (vertebral changes) is not highly specific, with co-morbidity a major confounder, explained Steyn. Many people dying of other diseases, especially lung diseases, may have had TB at some point in life and thus the diagnosis of TB based on skeletal changes alone is difficult.
The group is currently looking at artificial intelligence as an aid in diagnosing TB in skeletal remains.
“We are using machine learning and decision-tree analysis to detect patterns of skeletal changes in TB, and to determine patterns and associations between variables. Thus far we have produced a model with a moderate classification rate based on four variables. Advanced statistical analyses in palaeopathology are rare, and this method holds some potential to explore patterns of skeletal changes that may not otherwise be possible.”
In this work the sample sizes remain small. Individuals from mining contexts were mostly young males and, in modern skeletal collections, usually include unclaimed bodies. These demonstrate the plight of the poorest of the poor. In the last 20 to 30 years Anatomy departments rely mostly on donated remains, which are usually older people. The legacy collections are therefore very valuable but there are ethical issues we need to recognise. “There are lots of conversations going on in the field, an increased awareness and sensitivity, and much more control in ethical requirements for studies from ethics committees. It’s a sensitive issue and must be treated with respect for culture and the individuals concerned,” said Steyn.
Michelle Galloway: Part-time media officer at STIAS
Photograph: Noloyiso Mtembu