The rising tide of tuberculosis

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While the number of cases of tuberculosis has plunged in Britain, the development of highly drug-resistant strains mean this disease may be poised to make a comeback, says Jane Downey.

Prior to the discovery of streptomycin in 1952 by scientist Selman Waksman, tuberculosis (TB) was a major killer, not only in the developing world, but also in the UK. Although some regained their health spontaneously without effective medication, many did not – including the novelist George Orwell who, according to his biographer, battled feverishly to complete his seminal work 1984 before the disease laid his creative genius to rest in 1950.

TB is caused by bacteria belonging to the mycobacterium tuberculosis complex. From a global perspective, in 2011 there were nearly nine million new cases of TB and 1.4 million deaths from TB, and it is the leading cause of death among curable infectious diseases (Health Protection Agency (HPA), 2012).

quotemarksTuberculosis is the leading cause of death among curable infectious diseases.”

In 1991, the World Health Organisation (WHO), concerned by the steadily increasing number of cases of TB globally, implemented a strategy with two major targets. The first was to detect 75% of new sputum-positive cases of TB and the second was to cure 85% of these cases by the year 2000.

In 1994, this strategy was enhanced by focusing on a number of key components such as government commitment, case detection and standardised short-course chemotherapy for all confirmed sputum smear-positive cases, with a system of regular medication supply together with a programme monitoring system.

This strategy became known as “DOTS” (directly observed therapy) and has subsequently been expanded and implemented in 182 countries. DOTS implementation has assisted countries in improving national TB control programmes and managing the disease effectively. By 2004, more than 20 million patients had been treated by DOTS programmes globally and more than 16 million of these had been cured. Mortality due to TB has been falling and TB incidence declining or stabilising in all world regions except sub-Saharan Africa and Eastern Europe (WHO, 2010).

In the UK, TB was a major concern for the Department of Health (DH) from the mid-1990s until 2008, when its advance was stemmed by the implementation of the highly effective action plan Stopping Tuberculosis in England, based on the WHO’s TB strategy and implemented by the then chief medical officer Sir Liam Donaldson (DH, 2004).

The dramatic rise in UK cases in 1990 was related to higher migration levels of people from countries where TB was more prevalent, as well as the ageing of the established population and increased numbers of people with HIV.

The success of the DH strategy was partly because it used the WHO-recommended approach to TB, which emphasised the importance of early intervention and treatment, as well as raising awareness of the signs and symptoms of TB, not only in the general public but also healthcare practitioners and those who may be dealing with high-risk groups (DH, 2004).

In 2011, although the incidence of UK TB cases slightly increased compared with 2010, the overall picture indicates that rates have stabilised since 2005.

As in other European countries, the majority of cases are located in urban areas and it is more common among young adults and people who have migrated from sub-Saharan African countries or Eastern Europe. It is also more prevalent in people who have HIV or social risk factors.

The reactivation of latent TB infection in those born in areas of high incidence outside the UK is thought to be one of the major causes of TB cases in Britain, so although the strategy has resulted in increased treatment completion there has not yet been a major decline in the number of cases.

Another concern is the worldwide rise of multi-drug-resistant (MDR) TB. Although cases of MDR TB remain low in the UK, and usually relate to those born in areas of the world that have major problems with MDR TB or have social risk factors that raise the likelihood of inappropriate treatment interruption, it is still a public health concern and clearly demonstrates that complacency is not an option (HPA, 2012).

Role of OH practitioners

For OH practitioners working in the NHS, the assessment and screening of prospective employees is a normal part of their daily practice. However, for practitioners working in private companies this is not the case.

quotemarksThe majority of tuberculosis cases are located in urban areas and it is more common among young adults and people who have migrated from sub-Saharan African countries or Eastern Europe.”

The OH NHS Plus TB policy, based on the National Institute for Health and Clinical Excellence’s (NICE) TB guidelines, provides detailed guidance on NHS OH departments’ responsibilities regarding the management of TB.

For example, there are different levels of pre-employment TB screening depending on whether or not the prospective employee will be having clinical contact with patients and whether they have worked or lived in an endemic area within the last five years.

Once they start work, any employees exposed to TB will be reviewed, monitored and treated where necessary. There is also an emphasis on raising awareness of TB signs and symptoms so that concerned employees can access advice and care from OH services earlier rather than later (NHS Plus, 2010).

But what about non-NHS OH practitioners who may go for years without being involved in managing a TB incident in the workplace?

Although the principles of management will be the same and in line with the NICE TB guidelines, there is unlikely to be baseline information on employees who may be classed as “contacts” and possibly no written protocol that the practitioner can access.

The following sections outline the role of the HPA in the case of a workplace TB incident. We discuss how the OH practitioner can assist and ensure that they, as a public health practitioner, collaborate effectively so that the affected employee is able to return to work – with suitable adjustments if necessary – and any employees who could be classed as “contacts” receive the necessary screening and advice.

Screening, treatment and the HPA

Diagnosing and treating active respiratory TB
The HPA has a statutory responsibility for the management of TB incidents in the workplace, or in any instance where screening needs to be extended beyond the household setting for all smear-positive pulmonary TB cases. A risk assessment is undertaken by the local health protection unit (HPU), together with the local TB nursing service to ensure that contacts are identified and offered screening.

Signs and symptoms of active TB
If there are any symptoms of active respiratory TB – such as a persistent cough, coughing up blood, fever, night sweats, unexplained weight loss or fatigue – the HPA will arrange a chest X-ray and sputum specimens will be taken for microscopy and culture. If these tests are positive, the employee will need to commence treatment for active TB straight away.

Standard drug treatment for active TB and return to work
The employee will normally have six months of isoniazid and rifampicin, together with pyrazinamide and ethambutol for the first two months. Once the affected employee has completed two weeks of treatment, they are generally considered to be no longer infectious and can, if they feel well enough and their physician agrees, return to work (NICE, 2011). The OH professional can carry out an assessment and advise whether the employee is able to return to their normal hours and role or if temporary workplace adjustments would be beneficial.

Defining close contacts

TB can affect any part of the body, but is only infectious when found in the lungs or larynx.

quotemarksClose contacts are normally defined as those who have had contact with the TB-carrying individual for a period of eight hours or more per week during the infectious period in an area equivalent to a household sitting room.”

Patients who have smear-positive pulmonary TB – when TB mycobacteria are seen on microscopy from sputum samples – have the greatest potential of transmitting the infection to others.

Although the HPA or community TB nurse has responsibility to follow up “TB contacts”, the OH professional can assist this process by liaising with managers and help the HPA or TB nurse to compile a list of employees who were in contact with the infected employee from the time of symptom onset.

TB requires close and prolonged contact in order to spread. Close contacts are normally defined as those who have had contact with the TB-carrying individual for a period of eight hours or more per week during the infectious period in an area equivalent to a household sitting room.

Any employees who are identified as close contacts will be offered screening through their local TB service.

Other employees who have had occasional contact with the sputum-smear-positive employee will be viewed as casual contacts and will be offered information and advice in the form of a standard letter prepared by the HPA.

In some circumstances – for example, where workplace contacts are immune compromised – screening may be offered even if the person has not been in contact with the infected individual for a period of eight hours or more.

This will be assessed by the HPU and TB nurses at the incident meeting. Further advice is also available through the HPA website.

Latent infection

Contact screening will assess whether the identified contacts of the infectious case have signs of active TB or latent TB infection (LTBI).

LTBI occurs in about 10% of contacts of smear-positive pulmonary TB patients. Contacts with LTBI do not have the active TB disease, have no symptoms of TB and cannot pass TB on to anyone else.

Those with LTBI have a 10% risk of progressing to active TB in their lifetime (10% annual risk if they are HIV positive), and if they are below 35 years of age they may be offered chemoprophylaxis to eradicate the infection.

Screening methods

The type of screening offered to close contacts will depend on age and whether they have had a Bacille Calmette-Guerin vaccination in the past.

Contacts aged 35 years and under will be offered a Mantoux test (a type of skin test), while contacts who are over 35 years of age will be offered a chest X-ray.

If the results of the Mantoux test indicate concern, a blood test – the interferon-gamma test – may also be carried out. If the results of these are negative, the contact will be discharged once they have been given standard information and advice. If the test results are positive, further tests will be done to rule out active TB.

Maintaining progress at a national and global level

While the DH’s 2004 plan “Stopping Tuberculosis in England” was highly effective in reversing what had almost become an epidemic of cases in the 1990s, we cannot afford to be complacent.

The WHO’s global statistics demonstrate that TB is second only to HIV/Aids as the greatest killer worldwide caused by a single infectious agent. Ninety-five per cent of TB deaths occur in low- or middle-income countries, and it is the leading killer of people living with HIV, causing 25% of deaths within this group.

quotemarksWHO statistics demonstrate that the number of people falling ill with TB each year is slowly declining.”

MDR TB is present in virtually all countries surveyed and remains a major concern. It is a type of TB caused by bacteria that do not respond to isoniazid and rifampicin, the two most effective standard TB drugs. Its cause is directly attributable to inappropriate treatment as a result of the incorrect use of anti-TB drugs or use of poor-quality medicines, which then leads to the development of drug resistance.

MDR TB can be treated and cured by using second-line drugs. There is, however, a limited number of drugs that are effective and when they are used they can produce severe drug reactions. Certain countries or populations may also find these drugs more difficult to access, but if they are to be effective they will need to be given for longer periods than first-line drugs – up to two years in some cases.

To complicate the situation further, an even more severe drug resistance can develop, known as XDR TB.

This form of TB responds to even fewer available medicines, including the second-line anti-TB drugs. The WHO estimates there were 650,000 cases of TB globally in 2010, and of these 9% had XDR TB. Some 440,000 became ill with MDR TB and 150,000 died because of this form of the disease.

However, WHO statistics demonstrate that the number of people falling ill with TB each year is slowly declining, and the death rate decreased by 40% between 1990 and 2010 – which means it is on track to achieve its UN Millennium Development Goal to reverse the spread of TB by 2015.

OH practitioners, as public health employees dealing with working populations, need to play their part in making this goal a reality.

It is vital to work collaboratively and effectively with external partners such as the HPA, TB nurse specialists and GPs should cases arise in employees.

If the WHO goal is to be realised, it is just as important that OH does the same with internal partners such as managers, HR and employees.

Raising awareness about TB, early intervention and stressing the importance of adhering to treatment regimes are essential elements of managing this debilitating disease. OH is ideally positioned to play an instrumental part in this process, so let us ensure that we have the knowledge, confidence and networking skills to do so.

Jane Downey MSc (Org psychiatry and psychology), SCPHN (OH), RGN is an OH nurse adviser

References

Pedrazzoli D, Fulton N, Anderson L, Lalor M, Abubakar I, Zenner D (2012). Tuberculosis in the UK: 2012 report. Health Protection Agency.

Department of Health (2004). “Stopping tuberculosis in England: an action plan from the chief medical officer”.

National Institute for Health and Clinical Excellence (2011). Clinical guideline CG117: clinical diagnosis and management of TB and measures for its prevention and control.

Vivian C (2009). “NHS policy for occupational health management of TB”. NHS Plus.

World Health Organisation (2009). “Treatment of TB: guidelines for national programmes”.

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