Tuberculosis: Types, Causes, Treatment And Prevention

Introduction

Infectious diseases are very common in the Indian subcontinent. It is commonly encountered in clinical practice and has been around for many years. Unfortunately, despite the number of measures that have been taken by the Indian government and medical bodies, tuberculosis still remains quite rampant in our country.

The World Health Organisation estimates that there were over 2.79 million cases of tuberculosis in 2016 in India. This is quite a high number and is rather alarming.

The problem with tuberculosis is that it can affect any part of the body. The most common type of tuberculosis that is encountered in India is pulmonary tuberculosis. This is the type that affects the lungs.

In this article, we shall briefly take a look at tuberculosis, what causes it, what the clinical symptoms are, the different types of tuberculosis and how it is managed in India.

What is Tuberculosis?

• Tuberculosis is a clinical condition that is caused by a bacterium called Mycobacterium tuberculosis. As it affects multiple vital organs, it is described as a multi-systemic infectious disease.
• In 2015, the World Health Organization estimated that there are over 1.8 million deaths from TB worldwide.
• Tuberculosis is sometimes called Koch’s disease.
• If you look at the history of tuberculosis, infections have been dated back all the way to 8000 BC. The disease has remained rampant particularly in tropical countries. In India, the disease is still quite prevalent, and many people continue to be affected by this problem. Other countries where tuberculosis is also prevalent include China, South Africa, Pakistan, Indonesia and Nigeria.

Types of Tuberculosis

• Broadly classified, there are two types of tuberculosis infections.
• In active tuberculosis, the individual who is carrying the organism has active symptoms and can transmit the infection to other people.
• In latent tuberculosis, the individual carries the bacteria but does not exhibit any symptoms whatsoever. This is because immunity fights the infection and is able to suppress it to an extent. Individuals suffering from latent tuberculosis cannot transmit the illness to others. However, at some point in their life, the bacteria can get reactivated and the infection can become active tuberculosis.
• Another way of classifying tuberculosis is based on the organs affected. For example, if the bacteria affects the lungs, it results in a condition called pulmonary tuberculosis. If the bacteria affects the bladder, it can cause bladder tuberculosis. Similarly, if it affects the spine, it can lead to tuberculosis of the spine which is also called Potts disease or Potts’s spine. Tuberculosis can also affect the skin, brain and even the heart.
• Sometimes, tuberculosis infections are not caused by Mycobacterium tuberculosis. Instead, they are caused by organisms called atypical Mycobacterium. These include the Mycobacterium avium complex, Mycobacterium kansasii and Mycobacterium fortiutum.

What Causes Tuberculosis?

• As I have previously mentioned, the primary cause of tuberculosis is a rod-shaped bacteria called Mycobacterium tuberculosis. Common terminology for tuberculosis is TB.
• The bacteria that causes tuberculosis can be easily identified due to a number of different characteristics. These bacteria are dependent on oxygen for their growth and hence flourish in areas where there is a good amount of oxygen and nutrients. They are slow-growing bacteria and can take a while to go to a point where symptoms develop.
• Around the bacteria is present a protective lining. This protective lining prevents the body’s natural immunity from fighting and destroying the bacteria. By keeping themselves protected, Mycobacterium tuberculosis can spread from one part of the body to another through the blood or lymphatic pathways.
• Once it affects a particular area, it leads to the formation of a lesion that is called a granuloma. Granulomas have a characteristic appearance under the microscope. It is the presence of granulomas that helps a pathologist determine whether an individual has tuberculosis are not.
• An old granuloma can get covered by a fibrous capsule which can protect the tuberculosis bacteria. This is what happens in latent tuberculosis which later on reactivates into an active form.

Risk Factors For Tuberculosis

• Tuberculosis is usually spread from one person to another through droplet infection. This means that if an individual is carrying the tuberculosis bacteria in their lungs, by coughing up phlegm that carries the tuberculosis bacteria, they can spread it from one individual to another. In other words, tuberculosis spreads only on close contact.
• There are a number of different risk factors that are responsible for the development of tuberculosis. People who are constantly exposed to those people who have the bacteria are more prone to picking up the infection. Tuberculosis generally affects people of the lower socio-economic classes because of a lack of sanitary conditions and closed living spaces.
• Individuals who are drug abusers can also pick up tuberculosis. The presence of the human immunodeficiency virus i.e. HIV is a strong risk factor for tuberculosis as well.
• Children have poor immunity at their younger age. If they are exposed to someone to tuberculosis, their weak immune system is unable to fight the bacteria and they can get infected.
• Individuals who have cancer have low immunity as well and are prone to developing tuberculosis.
• Those who suffer from diabetes also have altered immunity and may have an inability to fight the tuberculosis bacteria.
• Finally, individuals who are taking certain medications that suppress their immunity are also prone to picking up tuberculosis infection.
• It must be remembered that tuberculosis does not really spread that easily from one person to another. It is usually the constant exposure to the bacteria that causes it rather than a one-off exposure. Those who have a family history of tuberculosis generally are exposed to the bacteria over the years which can increase the risk of developing the problem.

Often patients undergoing medication for tuberculosis stop or skip doses due to common side effects such as nausea. However, it’s crucial that medication is never missed and taken exactly as prescribed by a doctor. Interrupting the treatment course can aggravate tuberculosis and potentially result in drug-resistant tuberculosis, which is even harder to treat and may require regular use of injectable antimicrobials.

Dr. Arpit Verma, MBBS, MD (Pharmacology)

What are The Clinical Symptoms and Signs of Tuberculosis?

Given that most of the patients who suffer from tuberculosis have pulmonary tuberculosis i.e. tuberculosis of the lung, we shall take a look at the symptoms first before looking at other ones.

1. Pulmonary Tuberculosis:

The most common symptom in tuberculosis of the lung is fever. Fever can be a low-grade fever that rarely crosses 100 °F. Generally, patients may not feel the fever as it hovers around 99 °F or slightly more. However, they may feel excessively tired and maybe losing weight for absolutely no reason whatsoever.

In those who have advanced lung tuberculosis, cough can be a significant problem. Associated with a cough is the production of copious amounts of phlegm. This phlegm can be blood-stained and thick.

Unexplained weight loss in the absence of a change in diet or increasing exercise can sometimes indicate tuberculosis in India. The weight loss is often significant, and people tend to notice that the clothes are a lot looser than normal.

2. Pleural Tuberculosis:

If tuberculosis affects the lining of the lung i.e. the pleura, there can be an accumulation of fluid in between the two layers of the structure. This is called pleural effusion. Large pleural effusions can be seen in tuberculosis. Sometimes, they can be so large, they begin to compress the underlying lung. This can make it difficult for the lung to expand when a deep breath is taken. This can make the individual rather breathless.

In other words, breathlessness is a symptom of lung tuberculosis. In addition to this, fever, weight loss and other symptoms previously described will also be present.

Sometimes, the pleural fluid can become heavily infected and thick like pus. This condition is called empyema and requires emergency admission for drainage and treatment.

3. Skeletal Tuberculosis:

In skeletal tuberculosis, the tuberculosis bacteria affect the spinal column. As previously discussed, it is called Pott’s disease.

In skeletal tuberculosis, the primary symptom is pain along the spine. As the infection affects the spinal column, the nearby muscles begin to get irritated and can go into spasm. This can lead to a great deal of back stiffness.

If tuberculosis is untreated, it can worsen the health of the spine and begin to affect the spinal cord itself. In rare cases, it can lead to paralysis.

Associated with skeletal tuberculosis symptoms are also the general symptoms of weakness, fatigue and fever.

4. Brain Tuberculosis:

Brain tuberculosis is called tuberculous meningitis or TB meningitis. Here, patients experience variable degrees of headache associated with an altered state of mental health. Family members usually notice that the patients are confused and behaving in an erratic manner which is unlike their normal behaviour. If the infection persists and is not treated soon, they may slip into a coma which can be difficult to treat.

5. Bladder and Kidney Tuberculosis:

Tuberculosis can also affect the bladder and lead to a condition called TB cystitis. Here, there is the presence of pus in the urine associated with a burning sensation. However, when a urine culture test is done, there is no evidence of any organisms. This is called sterile pyuria.

Sometimes, tuberculosis can go on to affect the kidneys as well. This can lead to pain in the flanks, increased frequency of urination and a general feeling of being unwell.

6. Joint Tuberculosis:

Tuberculosis can also affect the joints leading to a condition called TB arthritis. The most common joints affected are the hip joint in the knee joint. Symptoms include pain and restricted mobility associated with a low-grade fever. It is often mistaken for simple arthritis so it is important to have a high clinical suspicion.

7. Gastrointestinal Tract Tuberculosis:

Tuberculosis can affect any part of the gastrointestinal tract all the way from the food pipe to the last part of the bowels. This can lead to a number of different symptoms such as difficulty swallowing, diarrhoea, poor absorption of nutrients, abdominal pain and even ulcers in the stomach. Associated with this is the presence of a low-grade fever and generalised fatigue.

8. Miliary Tuberculosis:

In this kind of tuberculosis, the lung is extensively involved throughout. There are multiple patches seen throughout the lungs on a chest x-ray.

There are two entities of tuberculosis that you should be aware of.

One type is called multidrug-resistant glasses or MDR tuberculosis. In this kind of tuberculosis, patients are resistant to the commonly given medications to manage the condition. Here, different medicines that are less often used must be prescribed to achieve a complete cure.

However, in some individuals, even medications that are rarely used also do not work. This type of tuberculosis is called extensively drug-resistant tuberculosis or XDR TB.

Diagnosis of Tuberculosis

A diagnosis of tuberculosis can sometimes be quite a difficult and laborious process. This is because tuberculosis can sometimes be active, but in some individuals, it can be latent.

The first step in making a diagnosis of TB is a clinical history. The physician treating the patient must be able to determine whether the symptoms point towards tuberculosis or not. This can sometimes be quite difficult given the symptoms are rather vague at times.

Once the clinical suspicion of tuberculosis exists, further investigations are required to confirm the diagnosis.

In those individuals who have pulmonary tuberculosis, a sputum examination may be done to look for the bacteria. There are specialised investigations for the sputum these days that do not just help grow a bacterium but also multiply it so that it can be detected by the pathologist.

Those individuals who have latent tuberculosis may not express the bacteria in the sputum.

1. Mantoux Test:

A Mantoux test is a skin test for tuberculosis. Here, an extract that is made from dead mycobacterium is injected right under the surface of the skin. This injection leads to an allergic response characterised by swelling, redness and firmness of the injected area. The presence of all three of these in a significant manner is a positive test. This diagnosis must be made by someone who is trained in interpreting the Mantoux test. If there is no firmness or redness, the test is negative.

However, a test can be positive if someone has already been vaccinated for tuberculosis with the BCG vaccine. A test can sometimes be negative even when an individual has got tuberculosis if they have poor immunity.

This makes the Mantoux test a less specific test and one that just aids but does not confirm a diagnosis.

2. Chest X-Ray:

A chest x-ray is a very useful test in the diagnosis of pulmonary tuberculosis. A lot of times, however, the chest x-ray can be normal. In those who have active tuberculosis, there can be present patches in the upper part of the lung which are rather diagnostic of the problem. In miliary tuberculosis, the infection can be a lot more widespread and appears like multiple patches all through the lung fields.

Sometimes, in those who have tuberculosis affecting the lining of the lung, there will be present evidence of fluid collection are on the lung. This can be clearly seen on a chest x-ray. Many times, this fluid itself guides the next step of obtaining a sample of this pleural fluid for analysis and determination of the tuberculosis infection.

3. Blood Tests:

Sometimes, the blood tests performed to diagnose tuberculosis can be negative for the presence of any infection. However, a specific test called the erythrocyte sedimentation rate or ESR is markedly elevated. These days newer blood tests such as adenine deaminase (ADA) have emerged as more specific markers for tuberculosis.

In those who have tuberculosis affecting the liver, there may be abnormal liver function tests. If the kidney is affected, the kidney function tests will be abnormal.

4. Ultrasound Scan of the Abdomen:

An ultrasound scan is a useful way to determine if there is any infection or abnormality within the abdomen. In tuberculosis, there may be certain specific changes that can be seen in the liver and other vital organs if they are affected by the organism. Given that it is a painless test, it makes it very easy to perform and can provide a wealth of information.

5. Urine Test:

In tuberculosis that affects the bladder, the urine will show the presence of pus cells. However, when a urine culture test is performed, there will be no bacteria present. This is called sterile pyuria and is characteristic of tuberculosis of the bladder.

6. CT Scan of the Brain:

When tuberculosis affects the brain, a CT scan can help determine the extent to which it is affected. Sometimes, an MRI scan may be required.

Tuberculosis Treatment In India:

• Once a diagnosis of tuberculosis has been confirmed, it is important to begin tuberculosis treatment. There are specific guidelines that have been published in India on how to treat tuberculosis. Given that patients can sometimes have an accompanying HIV infection, it is important to treat them both simultaneously.
• When considering the treatment of tuberculosis patients in India, two categories need to be considered. One category is those who have had no diagnosis of tuberculosis ever made and are taking treatment for the first time. The second category is those who have previously received treatment for tuberculosis and are having a recurrence.
• In those with a new diagnosis, the primary treatment regimen consists of a combination of drugs. This includes isoniazid, rifampicin, ethambutol and pyrizinamide. These are initially given for a period of 2 to 3 months following which the number of drugs reduces to just two. However, some protocols suggest giving three drugs.
• While taking the medications, it is important to monitor the liver function tests. This is because these medicines have a number of different side effects that can be quite toxic on the liver.
• In rural areas where tuberculosis is quite rampant, all patients receive their daily tuberculosis medicines under a protocol called directly observed therapy short term or DOTS. Here, a volunteer or a member of the family watches the patient take their medication regularly without fail. This is to ensure that the treatment that is given is followed religiously and patients do not miss any doses as this can be harmful.
• Fortunately, in India, fixed-dose combinations are readily available. This means that all tuberculosis medicines are available in a form that is easy to take.
• The usual course of treatment varies between 6 to 8 months. Once the treatment has concluded, further investigations may be done to ensure that no tuberculosis bacteria remain in the body. For example, a chest x-ray may be done to ensure that the chest is clear of the infection. Similarly, a urine test may be done to ensure the bladder is now clear of the tuberculosis infection.
• There remains an entity called multidrug-resistant tuberculosis where all the medications prescribed do not work. These people require specialised input from experts in tuberculosis management and often require injections on a regular basis to help cure tuberculosis.

Food For Tuberculosis

• There are no food recommendations for tuberculosis patients, and no diet can replace TB medication. You can, however, support your recovery by maintaining a healthy and balanced diet. Initially, you may have a poor appetite which makes it harder for your body to recover. It is important that you stick to at least 3 healthy meals during this stage and till you are fully recovered. The medications will help you to recover your appetite eventually while reducing the signs of tuberculosis. You should continue to strengthen your body with a nutritious diet as you get better.  
• Include cereals, pulses, vegetables, fruits, protein-rich foods (milk, meats, eggs), energy-rich foods (oils, nuts, fats, seeds). These can help you get stronger as the medications keep fighting the infection. While a healthy diet cannot cure you, a poor diet can make TB worse. Weight loss and malnutrition can be an issue, so be careful. 
• Note that, if you have pre-existing conditions (such as diabetes) you need to follow your doctor’s dietary recommendations properly.

Can TB be Cured?

The good news is that if medicines are taken as prescribed and they are able to get rid of the bacteria, then tuberculosis can be cured. However, it is better to take tuberculosis prevention steps rather than undergoing treatment for this problem.

Tuberculosis Prevention:

There are many ways to prevent tuberculosis. In children, the tuberculosis vaccine is administered to prevent TB infection in the future. The vaccine is called the BCG vaccine or Bacille Calmette Guerin vaccine.

Besides this, there does not appear to be an effective way of preventing tuberculosis. However, if there is someone in the family who are suffering from the problem, make sure you take the right advice on how to avoid contracting the disease. For example, someone with tuberculosis of the bladder will not necessarily pass on the infection to another. However, those who have tuberculosis of the lungs can pass the infection on from one person to another through infected sputum.

Prognosis of Tuberculosis:

Generally, people who receive timely treatment and complete the course without missing the medications do very well. The recurrence rate of tuberculosis is quite low and ranges from 0 to 14%. However, those who have had tuberculosis in the past and have reactivation reinfection do not necessarily have a good long-term outcome. Similarly, tuberculosis that affects elderly individuals or those who have poor immunity do not very well either.

Tuberculosis is a rampant problem in India. It presents with a number of different symptoms and can sometimes be rather difficult to diagnose. However, once a diagnosis has been made, it is fairly straightforward to treat provided there are no complications from the medicines themselves. In the long term, patients do very well and can be completely cured of the problem.

Also Read: 5 tuberculosis myths you need to know about.

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