What is TB? How does it spread?
Tuberculosis (TB) is an infectious disease caused by the bacteria known as Mycobacterium tuberculosis. Transmission occurs through the airborne spread of infectious droplets. When an infectious person coughs, sneezes or spits, they propel TB bacteria into the air. Left untreated, a person with active TB can infect an average of 10-15 people each year. Exposure to M. tuberculosis can lead to infection that is asymptomatic and non-contagious – referred to as latent TB. One in ten people not infected with HIV but infected with TB will become sick with active TB in their lifetime. Half of those who become infected with TB and progress to the development of active TB will do so within two years of infection, while in the others it occurs much later or not at all. People living with HIV are at a much greater risk of developing active TB once infected, which increases as the degree of immune suppression increases.
What factors affect TB transmission?
Businesses with a large migrant workforce, such as oil and gas companies, mining companies as well as health centres/ hospitals, are workplace settings where there is an increased risk of TB. Transmission generally occurs indoors, where droplet nuclei can stay in the air for a long time due to poor ventilation.
TB is also more easily spread in crowded living, working or social conditions, such as in hostels, prisons, military barracks, shebeens and some workplaces.
What is the difference between TB infection and disease?
TB infection occurs when TB bacilli are breathed in and establish infection initially in the lungs. In most healthy individuals the immune system is able to keep the infection in check. The TB bacilli survive by adapting their metabolism and slowing down their rate of replication. This is referred to as latent TB infection. TB occurs when conditions tip in favour of the TB bacilli because the immune system is weakened due to HIV infection, malnutrition, silicosis, cancer therapy or other chronic diseases such as diabetes, long-term steroid therapy, alcoholism, and physical and emotional stress. The TB bacilli then start replicating and causing increasing inflammation and tissue destruction until the person shows the signs and symptoms of TB.
How can TB be recognized?
If TB occurs following the initial infection, it is referred to as primary TB, which is common in children and HIV-infected individuals. TB in adults more commonly occurs following reactivation of a latent infection, most commonly in the apex of the lung or from sites of infection in other organs. This is referred to as post-primary TB. Pulmonary TB is the common and most contagious form of active TB. TB can occur in almost any other part of the body, including the lymph glands, pleura, joints, bones, meninges or intestines, and is referred to as extra-pulmonary TB. In HIV-infected TB patients, TB often affects more than one organ, and pulmonary and extra-pulmonary TB commonly coexist.
What is the rationale for prompt diagnosis?
The systematic and early identification in adults with a persistent cough lasting two weeks or more, among outpatients in health facilities at the workplace can detect a large proportion of sources of tuberculosis infection. This reduces treatment delays and identifies infectious patients who are a risk to the community and to other staff. Early diagnosis of TB that is treated effectively reduces the chances of dying from TB and reduces TB transmission to others.
How can cases of TB be found in the workplace?
Every patient who visits a health facility with a cough lasting two weeks or more should be regarded as a “tuberculosis suspect”. A patient showing symptoms who is or was in contact with a person with infectious tuberculosis is more likely to be suffering from TB. In settings of high TB and HIV prevalence and relatively poor access to health services like in South Africa, efforts to increase the identification of cases through awareness campaigns and the active screening of high risk groups are recommended by the Department of Health.
TB cases can be found even earlier through regular active case identification using symptom screening, sputum testing and chest X-rays if required. This further reduces TB transmission, leading to improved TB control. The WHO recommends that individuals seeking voluntary counselling and testing (VCT) and HIV-infected individuals seeking treatment and care should actively be screened for TB. Workers should be educated about the importance of seeking healthcare if they have a persistent cough or fever, drenching night sweats or unintentional weight loss. They need to be aware of how to get tested for TB, what this involves and, most importantly, that it will not affect their employment. Workers showing symptoms suggestive of TB at primary health or workplace clinics and outpatient facilities should be investigated promptly. Furthermore, they should be separated from other patients and workers until the diagnosis is excluded or confirmed and the patient is started on treatment. TB suspects should not, however, be discriminated against.
The workplace provides a unique opportunity to screen for TB, particularly when included as part of an annual medical examination. The entire workforce can be screened for TB once or twice a year using either a symptom screen alone or a combination of symptom and chest radiographic screening. Adding chest radiography to symptom screening substantially improves the ability to detect cases of TB. Although screening using sputum culture uncovers the greatest number of TB cases, this method substantially increases the workload of already overburdened TB laboratories and is therefore not recommended unless additional resources are available.
Workplace TB screening can identify undiagnosed TB cases that are either asymptomatic or present minimal symptoms which have not prompted the individual to seek care or in cases where the individual has sought care but the health service has not investigated for TB. Furthermore, workplace screening overcomes barriers to seeking care that are caused by poor access for whatever reason. Undiagnosed active TB cases found by active case investigation are more likely to be smear negative and have less extensive disease and lower mortality. As TB suspects identified by TB screening are more likely to be smear negative, it is advisable to also collect sputum for culture.
How is TB diagnosed?
When pulmonary TB is suspected, at least two sputum specimens from employees should be collected and examined by smear microscopy and culture. All specimens should be collected within two consecutive days and sent and examined as soon as possible and in line with National TB control guidelines.
The following should be considered in the diagnosis of pulmonary TB:
Why is it important to categorize TB before starting treatment?
Standardized case definitions for TB are used in order to assign appropriate treatment categories and facilitate the reporting of cases and treatment outcomes, and to enable the monitoring of trends. TB cases are categorized as:
How is TB treated?
The primary anti-TB medicines are Isoniazid (H), Rifampicin(R), Pyrazinamide (Z), Streptomycin (S) and Ethambutol (E). Apart from Streptomycin, the drugs are used in fixed-dose combination (FDC) tablets. Treatment regimens for new cases and retreatment exist for adult patients. Treatment is in two phases; an intensive phase (two or three months) and a continuation phase (four or six months). The aim of the initial intensive phase is to kill TB bacilli rapidly. The aim of the continuation phase of treatment is to destroy any lingering bacilli that could trigger a relapse. Treatment in the intensive phase is directly observed by a treatment supporter.
How can directly observed treatment be implemented in the workplace?
Directly observed treatment (DOT) is one method of promoting adherence to treatment. Studies show that at least one-third of the patients taking self supervised TB treatment do not take medicines regularly and, as a result, may remain infectious for a long time. The bacteria in their lungs may develop resistance to anti-TB medicines and those they infect will have the same drug-resistant strain.
DOT helps increase the likelihood of successful treatment outcomes and reduces the risk of the emergence of drug resistance. However, DOT is not limited to mere “supervised swallowing” but involves supporting patients by creating a human bond, which increases the probability of completing treatment. A person who delivers therapy and facilitates adherence by observing the patient swallowing the full course of the correct dosage of anti-TB medicines is called the DOT provider or treatment supporter. A DOT provider can be a healthcare professional, supervisor at the workplace, community health worker or a trusted friend of the patient who cares and will support the patient. A DOT provider is anyone who is acceptable and accessible to the patient, willing, trained and accountable to the health service. Patients have the option of identifying the most convenient DOT provider for them.
The workplace clinic is an ideal place for DOT to occur. Initial personal communication between the health staff and the patient to explain the treatment of TB is crucial; an explanation of the type of drugs prescribed, amount and frequency, possible side effects, frequency of sputum examination and follow-up appointments, and the consequences of irregular or incomplete treatment need to be communicated in a supportive manner. The patient should also be asked about contacts at home, should be informed of the risk of them getting infected and advised to ensure that they go to the nearest clinic for TB screening.
Ongoing counselling would ensure compliance and should be a part of patient management.
Elements of a Workplace TB Control Programme.
When can TB patients return to work?
Since patients with active TB may be sick and infectious, they may be advised to refrain from work during the initial stages of treatment until clinically better and they are no longer infectious. Most patients are no longer infectious after approximately two weeks of treatment. Such patients should continue treatment and can return to work; they are not a threat to other employees. TB patients in whom multi-drug resistance is confirmed or strongly suspected should not be allowed to return to work until they have had documented culture conversion of their sputum or are confirmed not to have resistant TB. Adequate sick leave should be available to employees to allow them sufficient time to recover, especially those with drug-resistant TB as they may require hospitalization for a few months.
Once the patient returns to work, s/he must be allowed time off work to visit the clinic for follow-up visits. If a TB patient is permanently incapacitated by TB and not able to return to work, then s/he should be dealt with according to the company’s policy on medical incapacitation and the country’s labour laws. If a patient is eligible for compensation, the appropriate procedures should be followed.
Can TB patients go on leave?
TB patients, particularly those with workplace DOT, should be encouraged not to take annual leave during the intensive phase of treatment. Prior to going on leave the patient should be re-counselled on the importance of continuing treatment while on leave. The patient should be supplied with adequate treatment for days away and be encouraged to use an alternative treatment supporter while on leave. Employees with TB going on extended leave should be transferred to their nearest clinic.
How should response to TB treatment be monitored?
The response to TB treatment should be monitored through bacteriological and clinical monitoring. This information is also used to monitor the performance of the TB control programme. If the healthcare staff are concerned that a TB patient is not responding to treatment, they should refer the patient back to the clinic as soon as possible for evaluation. The workplace clinic should work closely with the TB coordinator in the province or district programme to ensure TB patients are successfully cured. The workplace clinic should notify the state clinic if a worker is transferred to another operation or if a patient leaves employment, and should facilitate transfer of these patients to ensure continuity of care.
What is the association between TB and HIV?
TB and HIV form a lethal combination, each speeding the other’s progress. It is essential to offer TB patients HIV testing with counselling. HIV weakens the immune system, increasing the susceptibility of an individual to TB infection and the progression of TB infection to disease. TB is a leading cause of death among people living with HIV. Early diagnosis and effective treatment of TB ensures a cure and stops transmission to others. Among HIV-infected patients it is critical to diagnose and treat TB early in order to reduce mortality and morbidity. It is possible to treat TB and HIV together but the combined treatment may be associated with greater side effects. Refer to the TB/HIV fact sheet for more information.
What is drug-resistant TB?
Drug-resistant TB is when the bacteria are resistant to one or more anti-TB drugs. Drug resistance is possible in people getting TB for the first time, i.e. in patients who have not received prior treatment with anti-TB drugs; they may have been infected with drug-resistant TB or not disclosed previous TB treatment. Drug resistance occurs much more commonly in patients with a history of previous treatment (defaulted, failed or relapsed: re-treatment cases). Refer to the fact sheet on multi- and extensively drug-resistant TB.
How can TB be prevented in the workplace?
The three underlying principles of TB control are: FIND, TREAT and CURE and PREVENT
In addition to promptly identifying TB cases and ensuring they are treated and cured, TB can also be prevented by TB preventive therapy targeted to those who are at a high risk of developing TB, such as HIV-infected workers or those with silicosis, an occupational lung disease that results from silica dust exposure. Silica dust exposure may occur in mines, quarrying, sandblasting, tunnelling and smelting. The risk of developing TB in workers with silicosis can be reduced by isoniazid preventive therapy. After excluding active TB, isoniazid is given in a dose of 300 mg per day for six months to a year. Recently, guidelines for TB preventive therapy for silicotics in South Africa have been developed. http://www.wahsa.net.
Infection control is essential to prevent transmission of TB in healthcare facilities and other public settings where people tend to assemble. This is especially important to prevent HIV-infected individuals from being exposed to TB. The elements of a workplace infection control programme include:
Published by the World Economic Forum Global Health Initiative
First published on the South African Labour Guide website