Occupationally acquired tuberculosis: what's known

Tuberculosis Mortality by Occupation in South Africa, 2011⁻2015

Work-related tuberculosis (TB) remains a public health concern in low- and middle-income countries. The use of vital registration data for monitoring TB deaths by occupation has been unexplored in South Africa. Using underlying cause of death and occupation data for 2011 to 2015 from Statistics South Africa, age-standardised mortality rates (ASMRs) were calculated for all persons of working age (15 to 64 years) by the direct method using the World Health Organization (WHO) standard population. Multivariate logistic regression analysis was performed to calculate mortality odds ratios (MORs) for occupation groups, adjusting for age, sex, year of death, province of death, and smoking status. Of the 221,058 deaths recorded with occupation data, 13% were due to TB. ASMR for TB mortality decreased from 165.9 to 88.8 per 100,000 population from 2011 to 2015. An increased risk of death by TB was observed among elementary occupations: agricultural labourers (MOR_adj = 3.58, 95% Confidence Interval (CI) 2.96⁻4.32), cleaners (MOR_adj = 3.44, 95% CI 2.91⁻4.09), and refuse workers (MOR_adj = 3.41, 95% CI 2.88⁻4.03); among workers exposed to silica dust (MOR_adj = 3.37, 95% CI 2.83⁻4.02); and among skilled agricultural workers (MOR_adj = 3.31, 95% CI 2.65⁻4.19). High-risk TB occupations can be identified from mortality data. Therefore, TB prevention and treatment policies should be prioritised in these occupations.

Tuberculosis in healthcare workers: a molecular epidemiologic study in San Francisco

OBJECTIVE

Healthcare workers (HCWs) are at risk of becoming infected with Mycobacterium tuberculosis through occupational exposure. To identify HCWs who became infected and developed tuberculosis as a result of their work, we studied the molecular epidemiology of tuberculosis in HCWs.

DESIGN

Eleven-year prospective cohort molecular epidemiology study.

SETTING

City and County of San Francisco, California.

PATIENTS

All persons reported with tuberculosis between 1993 and 2003. HCWs were identified from the San Francisco Tuberculosis Control Section's database, and mycobacterial isolates from culture-positive subjects were analyzed by IS6110-based genotyping.

RESULTS

Of 2510 cases of tuberculosis reported during the study period, 31 (1.2%) occurred in HCWs: the median age of the HCWs was 37 years, and 11 (35%) were male. HCWs were more likely than non-HCWs to be younger (P=.0036), born in the United States (P=.0004), and female (P=.0003) and to not be homeless (P=.010). The rate of tuberculosis among HCWs remained constant during the study period, despite a significant decrease in the overall case rate in San Francisco. Work-related transmission was documented in at least 10 (32%) of 31 HCWs, including 4 of 8 HCWs whose isolates were part of genotypically determined clusters. Only 1 of 7 cases of tuberculosis in HCWs after 1999 was documented as being work-related.

CONCLUSIONS

Although most cases of tuberculosis in HCWs, as in non-HCWs, developed as a result of endogenous reactivation of latent infection, at least half of clustered cases of tuberculosis in HCWs were related to work. The number of work-related cases of tuberculosis in HCWs decreased during the study period.

High risk of Mycobacterium tuberculosis infection during the Hajj pilgrimage

INTRODUCTION

Annually more than 2 million pilgrims from all over the world attend the Hajj in Saudi Arabia. Overcrowding during this pilgrimage leads to a high risk of transmission of airborne infectious diseases. Tuberculosis (TB) is common among hospitalized pilgrims, but the overall risk of acquiring Mycobacterium tuberculosis infection during this pilgrimage is not known. We conducted a prospective study to assess the risk of M. tuberculosis infection among Hajj pilgrims.

METHODS

We measured the immune response to TB antigens using a whole-blood assay (QuantiFERON TB assay) prior to departure and 3 months after return from the Hajj pilgrimage.

RESULTS

Of 357 paired assays, 149 pilgrims were negative prior to the Hajj and 15 (10%) of these had a significant rise in immune response to TB antigens.

CONCLUSIONS

Pilgrims may be at high risk of acquiring M. tuberculosis infection during the Hajj. This has significant public health implications for TB control in countries with large Muslim populations.

Tuberculosis infection notification in Swiss medical students during their clinical electives

OBJECTIVE

The aim of this study was to assess the tuberculin skin test conversion incidence in Swiss medical students.

METHODS

This was a prospective cohort study of medical students at the University of Zurich, using a standardized tuberculin skin test before and after clinical electives.

RESULTS

Two hundred and sixty-two students accepted the invitation to the pre-clerkship test, and 155 (59.2%) subjects were retested after an average period of 2.25 years. An increase of more than 10 mm in the transverse diameter of the induration in the retest compared to the baseline test was observed in 12 (7.7%) students. The annual conversion rate was 3.4% (95% CI 1.8-6.0%).

CONCLUSIONS

Even in an industrialized country, the risk of tuberculosis infection--as estimated by the tuberculin skin test--is substantial for health care professionals. Possible explanations for the high incidence and possible bias are discussed.

Dying for work: The magnitude of US mortality from selected causes of death associated with occupation

BACKGROUND

Deaths due to occupational disease and injury place a heavy burden on society in terms of economic costs and human suffering.

METHODS

We estimate the annual deaths due to selected diseases for which an occupational association is reasonably well established and quantifiable, by calculation of attributable fractions (AFs), with full documentation; the deaths due to occupational injury are then added to derive an estimated number of annual deaths due to occupation.

RESULTS

Using 1997 US mortality data, the estimated annual burden of occupational disease mortality resulting from selected respiratory diseases, cancers, cardiovascular disease, chronic renal failure, and hepatitis is 49,000, with a range from 26,000 to 72,000. The Bureau of Labor Statistics estimates there are about 6,200 work-related injury deaths annually. Adding disease and injury data, we estimate that there are a total of 55,200 US deaths annually resulting from occupational disease or injury (range 32,200-78,200).

CONCLUSIONS

Our estimate is in the range reported by previous investigators, although we have restricted ourselves more than others to only those diseases with well-established occupational etiology, biasing our estimates conservatively. The underlying assumptions and data used to generate the estimates are well documented, so our estimates may be updated as new data emerges on occupational risks and exposed populations, providing an advantage over previous studies. We estimate that occupational deaths are the 8th leading cause of death in the US, after diabetes (64,751) but ahead of suicide (30,575), and greater than the annual number of motor vehicle deaths per year (43,501).

Onset of tuberculosis disease: new converters in long-term care settings

Elders living in communal settings, such as nursing homes or other types of long-term care facilities have a tuberculosis (TB) incidence rate of 39.2 per 1,000, nearly four times the rate of TB in the general population. This fact mandates routine screening, reporting, and strict follow-up of TB in long-term care facilities as well as recognizing and addressing barriers to worker and resident protection. As healthcare in this country evolves from acute care facilities to alternative ambulatory care settings, the focus for infection control personnel is to develop effective TB control plans appropriate to the care setting using current clinical guidelines set forth by the Centers for Disease Control and Prevention (CDC) or other agencies, the main goal of which is to reduce the number of infections and exposures to this disease. As the incidence of TB continues in long-term care settings, away from acute care facilities, public health officials, administrators, and infection control personnel need to develop TB control plans, risk assessment procedures, and appropriate follow-up on positive converters among the workers and the residents. The case study presented herein is a good example of an individual being offered a screening test for an infectious airborne disease and positive test results being disregarded.

Evaluation of a western blot test as a potential screening tool for occupational exposure to Mycobacterium tuberculosis in health care workers

Health care workers (HCWs) have a higher than average risk for contracting Mycobacterium tuberculosis (MTB) infection and tuberculosis (TB). No markers of MTB-exposure are available, and TB risk assessment is performed by tuberculin screening, identifying individuals with acquired MTB infection. This study evaluated a western blot (WB) anti-M. bovis A60 complex antibody as a MTB-exposure marker. WB reactivity was evaluated on 127 exposed and 28 non-exposed HCWs from four divisions of the Policlinico Hospital of Modena, and 140 non-exposed bacille Calmette-Guérin-vaccinated controls. Excess of occupational TB risk according to the Occupational Safety and Health Administration (OSHA) was calculated in each division. WB-positivity (%) was: (1) significantly higher in exposed HCWs compared with non-exposed (72% vs 25%, P < 0.00001), (2) highly related (r = 0.99) to OSHA risk excess in all divisions, (3) higher than non-exposed in HCWs with short (< 5 years) MTB-exposure (purified protein derivative [PPD], P > 0.18; WB, P < 0.04). PPD-positivity (%) was higher than controls only in HCWs with longer (> 5 years) MTB-exposure. The study suggests that the WB antibody might represent a more sensitive biological marker of MTB contact among exposed HCWs, related to the level of TB risk and detectable earlier than the PPD skin test, thus providing new tools for TB risk assessment in health care facilities.

Prevalence of positive tuberculin skin reactions in a two-step testing program at a tertiary-care center in eastern North Carolina

The results of performing two-step tuberculin skin testing of healthcare workers at a hospital in eastern North Carolina in 1997 and 1998 were reviewed. Of 1,248 new employees, approximately 500 required two-step testing, which identified only 5 new employees who might have been falsely labeled as converters during the subsequent year's surveillance testing.

Tuberculosis isolation: comparison of written procedures and actual practices in three California hospitals

OBJECTIVE

To evaluate implementation of healthcare worker exposure control measures for tuberculosis (TB)-patient isolation, as specified by Centers for Disease Control and Prevention (CDC) guidelines and the hospital's TB-control policy.

DESIGN

Prospective multihospital study comparing CDC guidelines and hospital policy for TB-patient isolation to once-weekly observations of TB-patient isolation practices over 14 consecutive weeks at each hospital.

SETTING

Three urban hospitals (two county, one private community) in counties in California with a high incidence rate of TB.

MEASUREMENTS

Work practices for TB-patient isolation were observed and ventilation performance of isolation rooms was assessed while patient rooms were in use for TB isolation.

RESULTS

Of 170 TB-patient rooms observed, 119 (70%) involved a patient in a designated TB isolation room, the room was under negative pressure, the door was closed, and a "respiratory precautions" sign was on the door; 32 patient-room units (19%) were not under negative pressure or not designated as negative-pressure rooms. Of 151 patient-room units mechanically capable of negative pressure at a prior point in time, 16 (11%) were not under negative pressure at the time of use. Of 67 patient-room units equipped with continuous monitoring devices, 8 (12%) involved devices that did not accurately reflect the direction of airflow. Of the 62 healthcare workers observed using a respirator for TB, 40 (65%) did not don the respirator properly.

CONCLUSIONS

Implementing CDC guidelines for TB-patient isolation was feasible but imperfect in the three hospitals. Day-to-day work practices deviated from hospital policy. Prospectively quantifying the implementation of a hospital TB isolation policy while the room is in use may lead to improved estimates of risk and may help to identify and thereby prevent avoidable healthcare worker exposures to Mycobacterium tuberculosis aerosol. Auditing practices and verifying equipment performance is likely to identify unexpected problems in implementation of the TB control program.

Tuberculin test conversion among employees of a tertiary care hospital in Riyadh, Saudi Arabia

BACKGROUND

The objective of this study was to determine the tuberculin skin test conversion rate, as well as the course and outcome of the converters, among employees of a tertiary care hospital. The study is a retrospective, cohort descriptive study undertaken at the King Faisal Specialist Hospital and Research Centre, in Riyadh, Saudi Arabia.

PATIENTS AND METHODS

The study was undertaken over a four-year period from 1993 to 1996, and the subjects were employees who had annual screening PPD skin tests. The outcome measures skin test conversion, prophylactic treatment with isoniazid (INH), side effects, and development of clinical tuberculosis.

RESULTS

A total of 6883 tuberculin skin tests were performed during the study period. The mean annual conversion rate was 1.55%. About 78% of the converters received INH prophylaxis, but only 75% of those who started chemoprophylaxis completed the course. The side effects of INH treatment were found in 23% of those on treatment, and one of the converters developed clinically active tuberculosis during the study period.

CONCLUSION

At the King Faisal Specialist Hospital and Research Centre, the mean annual tuberculin skin test conversion rate among employees is similar to that found in other studies, but compliance to oral isoniazide prophylaxis is low. There is a need to develop strategies to improve compliance.

Tuberculosis risk in funeral home employees

In order to estimate the risk of tuberculosis infection among employees in the funeral service industry, we conducted a risk-assessment study of a convenience sample of funeral home employees. Study participants completed a risk-assessment questionnaire and underwent tuberculin skin testing. Of 864 employees tested, 101 (11.7%) had a reactive tuberculin skin test. Reactivity to the tuberculin skin test was significantly associated with job category; funeral home employees with a present or past history of embalming deceased-human remains were twice as likely to be reactive as were non-embalming personnel (14.9% versus 7.2%, P < 0.01). Reactivity was also associated with age, gender, race, past history of close contact with a person diagnosed with tuberculosis, and work history. After controlling for age and other factors, tuberculin reactivity was found to be associated in embalming personnel with the number of years spent performing embalmings (> or = 20), and, in non-embalming personnel, with a history of close contact with infected individuals. Based on these results, it is recommended that funeral home employees who routinely embalm cadavers undergo annual tuberculin skin testing, receive initial training on tuberculosis prevention, and wear respiratory protection when preparing known tuberculosis cases.

Actions Taken by Nursing Education Programs in the United States to Prevent Tuberculosis Transmission in Nursing Students

Measures to prevent tuberculosis include education and skin testing of at-risk groups, including health care workers. This study focused on policies and practices related to tuberculosis in nursing education programs, especially skin testing and instruction. Data were collected from a stratified random sample of nursing administrators in associate and baccalaureate degree programs in the United States using an instrument adapted from a medical school study. Several factors may have contributed to fewer skin test conversions in nursing programs than in medical schools. Although most nursing education programs considered skin testing a priority, there were inconsistencies related to skin testing type and process when compared with recent Centers for Disease Control and Prevention guidelines. Major content gaps related to multidrug-resistant tuberculosis and the differences between pulmonary and extrapulmonary symptomatology were found.

Tuberculosis exposure and control in an urban emergency department

STUDY OBJECTIVE

To measure tuberculosis (TB) conversion rates among staff of an urban emergency department compared with other hospital employees (OHEs) and to evaluate the effectiveness of new TB control measures.

METHODS

A prospective interventional cohort study was performed in an academic adult 1,000-bed urban hospital, with more than 6,000 employees, and an annual ED census of 43,000. As part of a hospital-wide program, all employees were screened for tuberculin reactivity (Siebert purified protein derivative [PPD] of tuberculin) annually during a 3 1/2-year period. Additional information collected on each employee included country of birth, ethnicity, history of bacille Calmette-Gúerin (BCG) vaccination, length and site of employment, and age. At the end of the second year, TB control measures including construction of a new ED facility with TB respiratory isolation rooms, nonrecirculated air, and droplet shields for registrars were implemented. Relative risk (RR) and 95% confidence intervals (CIs) were calculated.

RESULTS

During the first screening cycle, PPD status was obtained on 5,697 hospital employees, 88 of whom worked primarily in the ED. Baseline status was 81% PPD- (induration <5 mm), 9% PPD+ (induration > or =10 mm), and 10% refused skin testing. ED staff did not differ from OHEs with regard to PPD status, age, ethnicity, BCG history, foreign birth, residing in a county with high TB prevalence, or length of employment. During the second cycle, 6 of 50 (12%) previously PPD- ED staff and 51 of 2,514 (2%) previously PPD OHEs converted to PPD+ status (RR=5.9; 95% CI 2.7,13.1). After implementing TB control measures, the conversion rate during the third year dropped to 0 for ED staff, whereas the OHEs had a conversion rate of 1.2% during that cycle.

CONCLUSION

TB conversion rates were 5.9 times greater in ED staff members than OHEs before engineering controls were implemented. The ED TB conversion rate fell dramatically in the year following new TB controls. Many EDs are high-risk sites for TB exposure and may benefit from similar measures.

Exposure Workups

Exposure workups are an important responsibility for infection control personnel. A well-designed plan for investigating exposures, which includes appropriate algorithms, will enable infection control personnel to evaluate exposures rapidly and consistently so that nosocomial transmission is minimized. Infection control personnel should use their own data to develop policies and procedures that suit the needs of their facility. After they have imple-merited the plan, infection control personnel should continue to collect data on exposures so they can continuously improve their performance.

Controlling tuberculosis in an urban emergency department: a rapid decision instrument for patient isolation

OBJECTIVES

This study examined whether data routinely available in emergency departments could be used to improve isolation decisions for tuberculosis patients.

METHODS

In a large emergency department in New York City, we compared the exposure histories of tuberculosis culture-positive and culture-negative patients and used these data to develop a rapid decision instrument to predict culture-positive tuberculosis. The screen used only data that are routinely available to emergency physicians.

RESULTS

The method had high sensitivity (.96) and moderate specificity (.54).

CONCLUSIONS

The method is easily adaptable for a broad range of settings and illustrates the potential benefits of applying basic epidemiologic methods in a clinical setting.

Mortality patterns among female nurses: a 27-state study, 1984 through 1990

OBJECTIVES

This study examined the mortality experience of 50,000 nurses using the National Occupational Mortality Surveillance database of death certificates.

METHODS

Proportionate mortality ratios adjusted by race (White, Black, or other) and 5-year age groups were calculated for selected causes of death among female nurses vs all workers and white-collar workers.

RESULTS

Excess deaths among nurses less than 65 years of age were seen in both comparison groups for viral hepatitis, cancer of the nasal cavities, accidental falls, suicide, and drug-related deaths. Among nurses 65 years old or older, deaths due to chronic myeloid leukemia were in excess. Proportionate mortality ratios for breast and colon cancers, diabetes, and heart disease varied by occupational comparison group.

CONCLUSIONS

These findings confirm results of previous studies and identify new associations. Redoubled efforts are called for in overcoming obstacles to reducing workplace hazards.

Tuberculosis in health care settings and the estimated benefits of engineering controls and respiratory protection

Intra-institutional spread of tuberculosis (Tb) has re-emerged as a substantial public and occupational health threat. To characterize the person-hours and lifetime risks of Tb-related morbidity and mortality, we performed a risk assessment for health care workers (HCWs) developing Tb-related morbidity and mortality at varying levels of exposure, engineering controls, and respiratory protection. Under average conditions of exposure, one Tb skin-test conversion is estimated to occur for every 2650 person-hours of work by unprotected workers. With higher exposures, a skin-test conversion for an unprotected worker may occur in as few as 3 person-hours. Use of respiratory protection is estimated to reduce risks by the following proportions: surgical mask, 2.4-fold; disposable dust, fume, mist, or disposable high-efficiency particulate air filtering (HEPA) mask, 17.5-fold; elastomeric HEPA cartridge respirator, 45.5-fold; or powered air-purifying respirator (PAPR), 238-fold. Assuming a lifetime exposure of 250 hours, the risk of a skin-test conversion is estimated to be 9%. We conclude that HCWs are at substantial risk for Tb-related morbidity and mortality, and that administrative controls, engineering controls, and respirators offer substantial benefits in risk reduction.

Tuberculosis in the Workplace: OSHA's Compliance Experience

Objective:

Inspections of 272 facilities were performed between May 1992 and October 1994 to determine compliance with applicable Occupational Safety and Health Administration (OSHA) requirements for prevention of tuberculosis (TB) transmission.

Design:

Retrospective record review of two data sources: (1) OSHA's Computerized Integrated Management Information System and (2) an inspector-completed questionnaire on inspection results.

Setting/Participants:

Inspections of five types of facilities: healthcare institutions, correctional facilities, homeless shelters, long-term–care facilities for the elderly, and others, including drug treatment centers that the Centers for Disease Control and Prevention (CDC) identified as having a higher than expected rate of TB.

Methods:

The OSHA Compliance Memorandum, based on the 1990 CDC Guidelines, which outlined elements of a TB prevention program, was used in performing 272 inspections of facilities between May 1992 and October 1994. Elements of compliance were recorded and reviewed from the IMIS database and inspectors' questionnaires.

Results:

Regulated facilities were not fully compliant with OSHA guidance. Generally, healthcare facilities performed better than other facilities. Most facilities (79%) were compliant with administrative elements of a comprehensive TB control program, such as early identification of known or suspected infectious TB patients and skin testing of workers. Only 29% of inspected facilities were found to have acceptable respiratory protection programs for the prevention of occupational TB.

Conclusion:

Facilities have not been fully compliant with the OSHA memorandum describing protection of workers from TB. Facility compliance was better with some traditionally recognized TB infection control elements, but was weaker in the area of respiratory protection programs. This may reflect a lack of familiarity with the latter type of hazard protection.

Risk to police officers from biohazards encountered in police work

The risk of contracting infectious disease in the course of police work is reviewed. The specific focus is on Acquired Immune Deficiency Syndrome (AIDS), hepatitis and tuberculosis. A review of the relevant literature and an assessment of the biohazard risk specific to police work is provided. The risk of AIDS and hepatitis C is seen to be less than the risk of hepatitis B. For these blood borne diseases, universal precautions are recommended. The application of such precautions to policing is outlined. Immunisation against hepatitis B is recommended. Tuberculosis is seen as a possibly increasing risk. A programme of surveillance is recommended. A review of post-exposure management is provided.