Public health implications of changing patterns of recruitment into the South African mining industry, 1973-2012: a database analysis.

BACKGROUND: The triple epidemic of silicosis, tuberculosis and HIV infection among migrant miners from South Africa and neighbouring countries who have worked in the South African mining industry is currently the target of regional and international control efforts. These initiatives are hampered by a lack of information on this population. METHODS: This study analysed the major South African mining recruitment database for the period 1973 to 2012 by calendar intervals and demographic and occupational characteristics. Changes in area of recruitment were mapped using a geographic information system. RESULTS: The database contained over 10 million contracts, reducible to 1.64 million individuals. Major trends relevant to health projection were a decline in gold mining employment, the major source of silicosis; increasing recruitment of female miners; and shifts in recruitment from foreign to South African miners, from the Eastern to the Northwestern parts of South Africa, and from company employees to contractors. CONCLUSIONS: These changes portend further externalisation of the burden of mining lung disease to home communities, as miners, particularly from the gold sector, leave the industry. The implications for health, surveillance and health services of the growing number of miners hired as contractors need further research, as does the health experience of female miners. Overall, the information in this report can be used for projection of disease burden and direction of compensation, screening and treatment services for the ex-miner population throughout Southern Africa.

Mining Migrant Worker Recruitment Policy and the Production of a Silicosis Epidemic in Late 20th-Century Southern Africa.

Objectives: Between the 1980s and 2000s, an epidemic of silicosis was identified in migrant black gold miners, many from neighbouring countries, who had worked in the South African gold mines. This study uses the newly available employment database of a large gold mining company to demonstrate how a sustained rise in employment duration in a new cohort of black migrant workers resulted from changes in recruitment policy, and it examines the implications for current surveillance and redress. Methods: Contract data of 300,774 workers from the employment database of a multi-mine gold mining company were analysed for 1973-2018. Piecewise linear regression was applied to determine trends in cumulative employment, including South African versus cross-border miners. The proportions with cumulative employment of at least 10, 15, or 20 years, typical thresholds for chronic silicosis, were also calculated. Results: Five calendar phases were identified between 1973 and 2018. During the second phase, 1985-2013, mean cumulative duration of employment rose fivefold, from 4 to 20 years. Cumulative employment continued to rise, although more slowly, before peaking in 2014 at 23.5 years and falling thereafter to 20.1 years in 2018. Over most of the 1973-2018 period, miners from neighbouring countries had greater cumulative employment than South African miners. Overall, the proportion of miners exiting with at least 15 years of cumulative employment rose from 5% in 1988 to 75% in 2018. This report identifies a number of fundamental changes in labour recruitment policy in the gold mining industry in the 1970s which provide an explanation for the subsequent rise in cumulative exposure and associated silicosis risk. Conclusions: These new data support the hypothesis of a silicosis epidemic driven by increasing cumulative silica dust exposure in a new cohort of circular migrant workers from the 1970s. They inform current programmes to improve surveillance of this neglected population for silicosis and related disease and to provide medical examinations and compensation to a large number of former gold mines. The analysis highlights the lack of information on cumulative employment and silicosis risk among migrant miners in previous decades. The findings have global relevance to the plight of such migrant workers in hazardous occupations.

Does Coronavirus Disease 2019 (COVID-19) Affect Perioperative Morbidity and Mortality for Patients Requiring Emergency Instrumented Spinal Surgery? A Single-Center Cohort Study.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic sent shockwaves through health services worldwide. Resources were reallocated. Patients with COVID-19 still required instrumented spinal surgery for emergencies. Clinical outcomes for these patients are not known. The objective of this study was to evaluate the effects of COVID-19 on perioperative morbidity and mortality for patients undergoing emergency instrumented spinal surgery and to determine risk factors for increased morbidity/mortality. METHODS: This retrospective cohort study included 11 patients who were negative for COVID-19 and 8 patients who were positive for COVID-19 who underwent emergency instrumented spinal surgery in 1 hospital in the United Kingdom during the pandemic peak. Data collection was performed through case note review. Patients in both treatment groups were comparable for age, sex, body mass index (BMI), comorbidities, surgical indication, and preoperative neurologic status. Predefined perioperative outcomes were recorded within a 30-day postoperative period. Univariable analysis was used to identify risk factors for increased morbidity. RESULTS: There were no mortalities in either treatment group. Four patients positive for COVID-19 (50%) developed a complication compared with 6 (55%) in the COVID-19-negative group (P > 0.05). The commonest complication in both groups was respiratory infection. Three patients positive for COVID-19 (37.5%) required intensive care unit admission, compared with 4 (36%) in the COVID-19-negative group (P > 0.05). The average time between surgery and discharge was 19 and 10 days in COVID-19-positive and -negative groups, respectively (P = 0.02). In the COVID-19 positive group, smoking, abnormal BMI, preoperative oxygen requirement, presence of fever, and oxygen saturations <95% correlated with increased risk of complications. CONCLUSIONS: Emergency instrumented spinal surgery in patients positive for COVID-19 was associated with increased length of hospital stay. There was no difference in occurrence of complications or intensive care unit admission. Risk factors for increased morbidity in patients with COVID-19 included smoking, abnormal BMI, preoperative oxygen requirement, fever and saturations <95%.

Enumeration and Survival of Salmonella enterica in Live Oyster Shellstock Harvested from Canadian Waters.

Since 2015, 11 recalls of live oyster shellstock have been issued in Canada due to the presence of Salmonella enterica. Six of those recalls took place in 2018. To understand this increase, fundamental information is needed on the relationship between S. enterica and oysters. The aims of this study were to address important data gaps concerning the levels of Salmonella in naturally contaminated oysters and the ability of this pathogen to survive in live oyster shellstock. Enumeration data were evaluated for five oyster and clam samples collected from the east coast of Canada from 2015 to 2018. The reported levels were <0.0015 to 0.064 most probable number per g of oyster tissue. The S. enterica isolates recovered from these animals belonged to serovars Typhimurium, Infantis, Enteritidis, and I 4,5:i:-. Filter feeding by the oysters was exploited to assess the Salmonella accumulation that would occur following a natural contamination event. Detectable levels of the pathogen were observed after 30 min of exposure and began to plateau at 60 min. A survival study in live oyster shellstock indicated that after 4 days of storage at ambient temperatures, the Salmonella level declined slightly from 4.3 to 3.7 log CFU/g. These data indicate that the levels of Salmonella found in naturally contaminated oysters are low and are not expected to increase between the point of harvest and the point of consumption. The changing ecology of shellfish environments requires continued monitoring and testing to safeguard public health. The data presented here will be useful for the evaluation and design of sampling plans and risk management approaches for the control of Salmonella in live oyster shellstock.