Communicable and Non-Communicable Disease: Tuberculosis and Cystic Fibrosis

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Communicable and Non-Communicable Disease:
Tuberculosis and Cystic Fibrosis

Biological Basis of Tuberculosis

Tuberculosis (TB), a communicable bacterial infection, is spread by airborne droplets of saliva expelled from the oral and nasal cavities of the infected individual. The bacterium responsible, Mycobacterium tuberculosis, is relatively slow-moving and thus symptoms may not become apparent in a patient for months or even years following infection. In addition to a slow symptom onset, this particular characteristic of the bacterium also means that, in order to catch TB, a person must be both in close contact with the infected individual, and exposed to them for a relatively long period of time. A second strain of the disease, caused by another rod-shaped bacterium (i.e. bacillus) called Mycobacterium bovis, can be spread from cattle to humans via infected milk products. M.bovis belongs to the same species (Mycobacterium), but belongs to a different species within the genus. Previously, M.bovis was a major cause of TB in children; however its incidence has declined in recent years due to the more widespread practice of pasteurisation. A typical bacterium is shown below:

Suspended within the cytoplasm of M.tuberculosis is a chromosomal loop which carries the bacterium’s genetic material. This is encased in a cell membrane, which controls movement of substances in and out of the bacterium, and a thicker cell wall which gives it its integrity. Surrounding the entire bacterium is a slime capsule which offers protection, particularly in terms of serving as a barrier against white blood cells in phagocytosis, and also aids attachment to other organisms. The bacterium is resistant as a result of this and can survive several weeks after the infected droplets have dried. As with all bacteria, M.tuberculosis is able to survive and reproduce autonomously, with no need for the host cells which viruses require.
Although primarily affecting the lungs, the disease has the capacity to spread to many other parts of the body, such as the bones or nervous system, if left untreated
Clinical features of tuberculosis only become apparent once the infection has reached the lungs, at which point the condition is known as pulmonary tuberculosis. At this point, the individual has already (most likely in their youth) suffered a primary infection, in which the bacteria begin to grow and divide in the upper regions of the lungs (where there is a plentiful supply of oxygen), but are controlled within a few weeks by the ingestion action of the body’s white blood cells. However, some of these bacteria usually remain inside the lungs and may re-emerge years later to cause the post-primary infection we know as pulmonary tuberculosis. Not as easily controlled as the initial infection, the bacteria destroy lung tissue, resulting in tissue cavities and irreversible scarring.
 A principal symptom of pulmonary tuberculosis is a persistent cough bringing up this damaged lung tissue, which contains the bacteria, and often blood. Medical advice is recommended if a patient suffers a persistent cough for three weeks or more, or immediately if the cough is productive.
Other symptoms of active TB include:

  • Fever (i.e. a temperature of 38°C or above),
  • Weight loss,
  • Night sweats.

In addition to this, the patient may notice the following signs:

  • Loss of appetite,
  • General weakness or fatigue,
  • Chest pain, or pain when breathing or coughing.

In cases of TB where the disease spreads beyond the lungs (known as extrapulmonary tuberculosis), additional symptoms may vary depending on the organs affected. For instance, bone pain may occur in sufferers of skeletal TB, and TB in the kidneys may cause hematuria (blood in the urine). The areas of the body subject to infection are:

  • Lymph nodes near the lungs (lymph node TB),
  • Bones and joints (skeletal TB),
  • The digestive system (gastrointestinal TB),
  • The bladder and reproductive system (genitourinary TB),
  • The nervous system (central nervous system TB).

In the case of a persistent cough, fever, night sweats and unexplained weight loss, a visit to a General Practitioner for examination is advised. TB can be diagnosed by him/her, or, alternatively, by a pulmonologist or an infectious disease specialist.

Causes and Distribution

Specifically in tuberculosis research, and in research into disease in general, epidemiology is of the utmost import as it allows relationships in demography and aetiology to be established, and patterns discovered, with a view to determining the most appropriate and effective means of prevention and cure.
Currently, approximately one third of the world’s population is infected with the TB bacilli. However, due to the prevalent latent form of the disease - where bacteria remain in the body from primary infection but do not actively re-emerge - the proportion of this third suffering from the infectious form is comparatively small. A morbidity rate of about 5-10% is estimated, i.e. 5-10% of individuals infected with the bacilli become sick/infectious at some point in their lives. Globally, the vast majority of TB deaths occur in the developing world, with over half in Asia. From the distribution map below (TPO) we can see that, in 2008, the majority (55%) of new cases of the disease were reported in Asia, followed by Africa (30%) and the Eastern Mediterranean (7%). Although the TB incidence rate is falling, the rate of decline is extremely slow - at less than 1% - and sufferers are still in their millions: in 2009, the global mortality rate for TB was equivalent to approximately 4700 deaths per day. Around nine thousand new cases of TB are reported in the UK every year.
Often referred to as a ‘disease of poverty’, TB is most readily transmitted in those conditions associated with less affluent areas, such as overcrowding, poor ventilation and malnourishment. Groups who are at greater risk of contracting the disease include those who:

  • are in close contact with the infected for long periods of time (i.e. living in crowded/poorly ventilated accommodation). It is for this reason that TB is most often spread between family members, close friends or work colleagues;
  • work or reside in long-term care facilities where many people live close together (e.g. hospitals, nursing homes, prisons);
  • come from a country where TB is common;
  • have reduced immunity.

It is for these reasons that the majority of cases within the UK are reported in major cities, particularly in London.
 Tuberculosis can occur at any life stage, although it is clear from the evidence above that individuals of certain ages are most vulnerable. In addition to this, the negative impact of the disease may be greater once contracted in reduced immunity groups.
Tragically, tuberculosis tends to instigate a vicious cycle, in that poverty can be seen as both a cause and consequence of the disease. Once a person is infected with TB, the entire family (and possibly even community) can suffer, as he/she will be unable to work and therefore his/her income will be suspended. Studies suggest that patients lose on average 3-4 working months, which amounts to a 20-30% annual loss in household income.
 Patients in the developing world may be unaware or unable to access free healthcare, and, where they are able, there is often a cost to travel to clinics, both to collect drugs and to have each dose supervised. This dose supervision is vital as patients have a tendency to cease taking their antibiotics before their course is finished, as soon as they begin to feel better. This is detrimental as, in such cases, it is the most resistant forms of the bacilli which survive, remain the body and consequently reproduce, strengthening the disease once more. As a result of such antibiotics misuse, a form of the disease known as ‘multi-drug resistant TB’ has developed. This strain does not respond to standard treatments using first-line drugs, and is present in virtually every country surveyed by the World Health Organisation (2009).
The graph above
 demonstrates the relationship between tuberculosis and poverty: as you can see, the incidence of the disease is strongly negatively correlated with countries’ relative GNP (Gross National Product), although this link becomes less pronounced once GNP exceeds around $5000 per capita.

Support, Diagnosis Facilities and Treatment in my Locality, and an Evaluation of Preventative Strategies and Factors Affecting Them

If tuberculosis is suspected, the main initial means of diagnosis is a skin test, most often the Mantoux test. In this test, a substance called PPD tuberculin is injected just under the skin of the forearm, and the emergence of a hardened red bump (an induration) 48-72 hours later indicates a TB infection. This is because, where an individual’s body has encountered the bacteria before, their immune response (the induration) occurs more quickly than those operating on a primary response. A simple procedure, this test can be conducted in General Practices nationwide, including those falling within my locality. Although blood tests - which can also be used to measure the immune system’s reaction to M.tuberculosis - are also available at most GP surgeries, samples taken may well be sent to a local hospital’s Phlebotomy Department for analysis. For instance, Stafford Hospital and Cannock Chase hospital manage a Specimen Reception which sends out laboratory result reports to GPs, as well as private consultants and their own wards.
Alternatively, patients could choose to utilise a private sector organisation such as MediChecks.
 Despite being based in London, MediChecks offers diagnostic blood tests to the entire nation via a pre-paid postage system and six hundred and eight-two test centres located throughout the UK. The patient provides their sample at their local centre; in my locality alone there is an abundance of options, including Cannock, Wolverhampton, Telford and several in Birmingham. They then post it to the laboratory in London for analysis, and receive their result either in the post or by email. Obviously, this means of blood testing is desirable in that the patient can choose when and where to give their sample. This would be particularly beneficial to an individual with compromised mobility, either physical or social. A service user may have a disability which makes travel - even to local hospitals which offer the service – impractical. Alternatively, they may have a child or adult who is dependent on them, thus making the prospect of free choice over appointment times an extremely appealing one.
However, there is one significant drawback to this particular route of diagnosis. As part of the private sector, the service is not provided on the NHS and therefore costs the patient money to obtain. In this case specifically, a test package for Mycobacterium tuberculosis costs £241: a considerable amount of money to most people. It is at this point an important issue in health care is raised: should an individual’s personal wealth affect the standard of care he/she can obtain? Whilst the private sector adds variety to Britain’s mixed economy of care, it could be argued to be discriminatory at times to those service users with access to less disposable income. On the other hand, legislation is in place which aims to provide every patient with the high quality care they are entitled to on the NHS alone. For instance, a disabled service user unable to pay for privatised care will be equally well catered for on the NHS under The Disability Discrimination Act (1995).
Blood tests, whilst useful in early diagnosis, cannot distinguish between latent and active forms of TB, and are limited in their ability to determine the extent of the infection. In order to investigate further, the GP may recommend a chest X-Ray. This could be conducted in a local hospital, such as Burton Hospital or Samuel Johnson Community Hospital in Lichfield, or alternatively it could be carried out within a specialist NHS clinic such as Shelton Chest Clinic in Stoke-On-Trent. The patient in question would need to weigh up the advantages of the clinic route - which, being specialised, would offer a plethora of experts in the relevant field – with the potential travel costs, dependent on where within the locality he/she resides. It may be worthwhile for the patient to note that, although a unit such as Shelton Chest Clinic will contain more chest specialists than their local hospital, it is likely that this hospital will still employ the consultants necessary to undertake the X-Ray and subsequent analysis required in this instance.

Being a bacterial disease, treatment of tuberculosis involves the use of antibiotics. In the UK, a service user diagnosed with TB will most likely be referred to a TB treatment team and assigned a key worker (i.e. a nurse or health visitor) to co-ordinate their care. Under this team’s observation, a six to twelve month drug course of a combination of antibiotics such as izoniazid and rifampicin is undertaken. The hospital in which this TB team is based could be some distance away from the home of the service user, and it is for this reason that ease of travel may well be an issue for some. If an individual is at times unable to make their appointments, which are either for monitoring or to receive further antibiotics, then this could severely compromise the effectiveness of the treatment. This is because monitoring, an essential component of the care planning cycle, is necessary in order to check the patient’s progress and make any of the required modifications to their provision based on this assessment. In the absence of this continuous evaluative process, the service user’s changing needs are not met and their recovery can suffer. In addition to this, if a service user does not complete the entire course of antibiotics as a result of a physical barrier to access such as geographic mobility, the drugs are rendered largely ineffective. This is because, when antibiotics are administered, they destroy the weakest infectious bacteria first, whilst the strongest, most resistant forms are killed last. Thus, if a patient ceases their course of antibiotics before it is due to finish, they are left with the most resistant bacteria in their body, which then reproduce and perpetuate the disease.
Another factor which may affect the outcome of tuberculosis treatment is the matter of finance - a significant issue for many service users. In previous years, when the costs of antibiotics for TB were charged to the service user directly, many were left simply unable to afford the treatments they required, and their condition inevitably suffered as a result. This lead to the amendment of The NHS (Charges for Drugs and Appliances) Regulations in September 2007, whose revised version aims to secure drug provision free of charge for those TB sufferers being treated either within TB clinics or under a patient group direction
 (a legal framework which allows certain health care professionals to administer medicines to certain patients without the need for a prescription). This will certainly carry a significant benefit to those service users for whom finance was previously an area of concern. However, the conditions under which this new legislation operates may still be challenging to achieve for some service users. For instance, due to dependency or travel issues, some individuals may find it difficult to spend a significant period of time (i.e. with regular visits or as an inpatient) in a TB clinic, or even to reach one in the first place. This is not aided by the fact that specialised TB clinics are not prevalent in the UK: one of the relatively few within my locality is encompassed within the University Hospital of North Staffordshire, located in Stoke-on-Trent, which limits the range of choice available for service users with restrictive circumstances, such as lack of access to private or public transport. The reason for this scarcity in clinical support around the UK is the relatively low incidence of the disease in this country in comparison with global figures. With an estimated nine million new cases around the world per year, only around nine thousand of these are reported in the United Kingdom: a percentage of 0.1%. Nationally, a disproportionate number of TB clinics are located in and around the United Kingdom’s major cities, with 33 in London alone. This is due to the nature of the distribution of the disease as previously discussed i.e. major cities have a higher TB morbidity rate than more rural areas as their conditions are such that they lend themselves more to the contraction and spread of the disease. This - logically - results in a wider breadth of provision in those areas most at risk, but could perhaps be seen to be discriminatory towards patients in other parts of the country who contract the disease, and are from that point onwards just as vulnerable as those living in high-risk areas. However, it is always the case that finances dictate the distribution of care facilities throughout the country, and that a TB clinic operating in a rural area - consistently failing to work to its full capacity - would be practically and economically unviable.
Physical face-to-face support for tuberculosis sufferers, other than that gleaned from treatment clinics, is relatively scarce, with internet forums such as Daily Strength
 and Cure Zone acting as the main source of provision. Such websites sustain an online community through which patients can vent emotions, offer advice and support one another through their condition, as well as providing helpful information and links to relevant pages regarding treatment, personal goal setting, etc. In more general terms, despite not being targeted specifically at TB patients, the British Lung Foundation (BFL) caters for sufferers of all forms of lung disease, and is a very active and well acclaimed source of support available nationwide. Among other things, the BLF offers a Helpline, a PenPals service and a network of support groups known as Breathe Easy (with thirty-two groups in my locality alone). In addition to counseling services, this Helpline also offers advice on any Welfare Benefits sufferers may be entitled to. This disparity in provision between that for TB, and for lung disease in general, can again be attributed to the relative incidence rates of the conditions. Lung disease is vastly more prevalent than tuberculosis alone in the UK, with one in every seven people in some way affected. From this evidence it is clear that the prevalence of a disease in a particular area is one of the many factors which influence the levels of provision available for its sufferers. However, the common cold is the most widespread communicable disease in the UK, and yet there is little to no available support for those who contract it. This demonstrates that the severity and duration of the disease in question also, in part, determine the related levels of provision it generates.
Socially, the avoidance or modification of those conditions conductive to the spread of tuberculosis is the most effective means of prevention. However, in many cases these conditions are inextricably linked to the context in which an individual finds him/herself, and are therefore very difficult to evade. For instance, residents within a care home for the elderly are, by their very nature, compromised in terms of immunity; both due to their age and the long-term close contact with others that characterises such institutions. In such instances, measures which could minimise an individual’s risk of contracting TB include opening windows to ensure adequate ventilation and maintaining a healthy diet, exercise and sleep pattern with a view to boosting the immune system. Such measures are easily undertaken by the majority of the population, including those residing in long-term care facilities. However, a factor which undoubtedly affects whether or not they are undertaken is the matter of education. Individuals who are not aware of the preventative measures described, or do not understand why they are necessary, are unlikely to implement them themselves (or, in the case of an authority figure such as a care home practitioner, encourage others to implement them). A lack of knowledge and/or understanding of tuberculosis prevention could be attributed to a number of factors, such as:-

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  • Poor quality/non-existent health promotion campaigns concerning the issue,
  • A shortage of related media or access to it (for instance due to geographical isolation, e.g. individuals living in parts of the world where educational media is scarce or controlled),
  • An inadequate or incomplete academic education in the case of some service users.

As a result of a deficiency in awareness or understanding, simple means of reducing the risk of contracting tuberculosis - such as the practice of good personal hygiene - are often not carried out, leading to an increase in the prevalence of the disease in the ...

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