VOL: 100, ISSUE: 36, PAGE NO: 48
Christine Bell, MSc, RGN, is tuberculosis nurse specialist, Department of Respiratory Medicine, Manchester Royal Infirmary
In the early part of the 19th century in Britain, as in most European cities, TB was one of the leading causes of death. However, a decline in the number of cases, which began at the beginning of the 20th century, became more dramatic in the 1950s with the advent of the bacille Calmette-Gu[ap6]rin (BCG) vaccination and the discovery of antibiotics used to treat the disease.
The number of cases in this country began to rise again in the late 1980s and this trend has continued with about 7,000 cases a year (Health Protection Agency, 2004), mostly occurring in inner-city areas.
The increase in incidence in the UK reflects the worldwide resurgence of TB, mainly in developing countries. The World Health Organization (WHO) declared a global epidemic of TB in 1993. There are two million deaths per annum from TB worldwide, and one-third of the world’s population is infected with the disease (WHO, 2002).
One of the contributory factors for the rise, particularly in Sub-Saharan Africa, is the spread of HIV/Aids, which suppresses the immune system, making it easier to contract the disease.
Transmission of TB
The risk of developing TB is related to the amount of exposure to the organism M. tuberculosis. In most, but not all cases, close prolonged contact is required. Those most likely to develop TB are people who live or have lived in countries where it is endemic, and people who have impaired immunity. Most cases in the UK therefore occur in those born in countries with a high incidence of TB. Risk factors in the Caucasian population born in the UK include high alcohol intake, old age and homelessness.
TB is an infectious disease that is spread through droplet inhalation from coughs. Only those who have the disease in the lungs and who are coughing the organism out are infectious.
Infection does not necessarily mean that disease will follow, as the so-called primary complex may be overcome by the host’s defences and could remain dormant for the rest of that person’s life.
The primary complex occurs when an inhaled bacillus in the lungs sets up a primary tubercle (nodular lesion) and spreads to the nearest lymph node. TB may then develop in the future.
In a small percentage of cases the disease develops from the primary complex. The tubercle bacilli may spread through the lymphatic system or the bloodstream to distant sites, such as the lymph node, bones or the kidneys (Grange, 2003). Although TB can occur in any part of the body, the most common site is the lung.
Diagnosis of tuberculosis
Patients with TB have a history of persistent symptoms that gradually worsen for at least a month. As the lungs are the most commonly affected site, there is usually a cough and occasionally haemoptysis (blood in sputum).
More generalised symptoms such as weight loss, anorexia and drenching night sweats are also a common feature. A chest X-ray is usually abnormal, with consolidation in an upper lobe being the most common appearance.
However, multiple lobes may develop in both lungs depending on the severity of disease. Intrathoracic lymphadenopathy (lymph node swelling) is also common. Sputum specimens should be obtained from the patient to confirm the diagnosis if the chest X-ray is abnormal (Box 1).
The sputum of patients with a diagnosis of TB is described as ‘smear positive’. This means that when the Ziehl-Neelson stain is applied, the acid-alcohol fast bacilli (AAFBs) can be seen through a microscope. The absence of AAFBs does not rule out TB but indicates that the patient is much less infectious.
Other non-specific markers such as a raised erythrocyte sedimentation rate or C-reactive protein may also be present.
Extra-pulmonary sites If extra-pulmonary sites are involved, the symptoms will relate to those areas, for example swelling in the case of lymph node TB, or back pain in spinal TB. Systemic symptoms may or may not be present.
A specimen should be sent for culture if it is possible to obtain a specimen from the site involved. This will confirm the diagnosis and provide information about the antimicrobial susceptibility of the organism.
Screening and vaccination
TB is a notifiable disease under the Public Health (Control of Disease) Act 1984, which means that the proper officer, usually the consultant in communicable disease control, must be informed of all new cases in the area. Each case is then investigated to determine which contacts should be screened.
As the biggest risk is to household contacts, they are generally screened regardless of the smear status or site of disease. If transmission is found in the group of contacts closest to the original case, the net is widened to include those with less contact.
Depending on the patient’s activities and lifestyle, the number of contacts can vary from none to hundreds. The TB nurse specialist will usually be involved in this contact tracing.
Heaf test
This is a skin test used to determine if children or unvaccinated adults have been infected with TB. The test identifies whether the immune system recognises TB. This may be due to previous BCG vaccination, current disease or infection. It is not a diagnostic test.
Children without a BCG scar or a record of previous BCG vaccination, who have a negative Heaf test, are given BCG vaccination. Those who have not been vaccinated but have a positive skin test, or those who have had previous BCG but have a strongly positive skin test, require further investigation to determine if they have simply been infected or have in fact developed the disease.
Children and young adults who are found to have been infected with TB but show no signs of disease are eligible for chemoprophylaxis.
This entails three months of treatment with the anti-TB drugs rifampicin and isoniazid or a six-month course of one of these drugs alone.
BCG vaccination does not provide total protection but it does reduce serious complications of TB in childhood and is recommended by WHO for all neonates in areas with a high prevalence of TB.
Anyone who has had contact with TB should be warned about symptoms and advised to seek medical help if they develop.
Treatment
TB is a curable disease. Treatment should be started as soon as possible, particularly in infectious cases to prevent further spread of the disease. It consists of combination anti-TB drugs. TB cannot be treated with a solitary agent, as it easily becomes resistant. There are two phases of treatment – an initial phase lasting two months and a continuation phase lasting four months (Box 2).
The role of the specialist nurse
Patients with TB should be monitored regularly to ensure that:
– No interruptions occur in treatment;
– Serious side-effects from the treatment are quickly identified;
– There is improvement in the patient’s condition, although this is often very gradual.
Home visits are the best way of making a holistic assessment of the patient’s needs and progress. Many patients have other problems, such as accommodation or immigration issues, which are often their main priority.
Patients often need help to deal with these more immediate difficulties before they will consider taking anti-TB medication and attending hospital appointments. The TB nurse specialist may be required to liaise with social services, the Home Office, and the National Asylum Support Service.
The nurse’s role is vital in the control of TB and for the successful completion of the patient’s therapy. Once a diagnosis has been made, the patient needs to be established on the correct treatment.
Many patients find the treatment course difficult at the start because they have to take numerous tablets, some of which are very large and have various side-effects. Later, when symptoms have resolved but the patient still has the disease, they may question the need for continued treatment.
TB nurse specialists can ensure that patients are given the correct medication and can provide support for patients and their relatives or carers to prevent lapses in treatment.
The TB nurse specialist can help to manage side-effects or drug formulations, take routine blood samples or occasionally arrange admission to hospital.
Concordance with treatment
Occasionally patients do not take their tablets despite extra support. Supervised treatment or directly-observed therapy (DOT) must be given because of the risk to the wider population. This involves a nurse visiting the patient at home three times a week and administering the treatment.
The dose of medication is increased because the treatment is not taken daily and therefore involves even more tablets.
This can be extremely unpleasant for the patient, as the tablets may be difficult to swallow. Side-effects are more common in intermittent therapy (see p52).
Infection control issues
Hospital One of the main areas of confusion in the management of TB in hospital is cross-infection and the correct precautions required to prevent it.
All health care professionals should have had their tuberculin status assessed before employment and should be given BCG vaccination if required.
Patients with smear-positive sputum must be nursed in a side room to prevent infecting other patients on the ward. If there are immunocompromised patients on the ward, patients with TB who have smear-negative sputum should also be nursed in a side room.
Patients with non-pulmonary disease, including pleural disease, are not a risk to others and can be nursed in an open ward. Those who are suspected of having pulmonary TB should be nursed in a side room until three negative sputum smears have been obtained. Patients must remain in their rooms with the door closed. If they need to leave the room, they must wear a mask.
Routine infection-control procedures for the handling of body fluids and specimens should be used, but special cleaning of rooms following isolation for TB is not required as TB is spread by droplet inhalation (Joint Tuberculosis Committee of the British Thoracic Society, 2000).
Nurses providing routine nursing care will not be exposed to undue risk, as close prolonged contact is usually necessary to acquire the disease. Masks are therefore not required, unless the patient is known to have multi-drug resistant TB (MDR-TB). This is much more difficult to treat, although it is no more infectious than fully sensitive TB.
Patients with infectious MDR-TB should be nursed in a side room with negative pressure ventilation and all staff and visitors should wear a dust/mist mask that meets the Personal Protective Equipment (EC Directive) Regulations 1992 (JTCBTS, 2000).
Children with TB should be nursed in a side room until their visitors have been screened, as they may be the source of the child’s disease.
Community Patients in the community who are infectious should not go to work or school, but should remain at home until they have had treatment for two weeks.
After this time they will no longer be infectious. Visitors should be restricted to those who have had recent contact, and these will be screened. The only children allowed should be those who live in the same accommodation.
Conclusion
TB is far from being a disease of the past and the number of cases is on the increase. Affected patients and their relatives require specialist care. The role of the TB nurse specialist in liaison with infection control nurses is vital to control and manage this disease effectively.
