What is Active Tuberculosis (Tuberculosis)?
Active tuberculosis, also known as TB, is a disease that can affect multiple parts of the body due to an initial infection, or as a return of a dormant TB infection. This makes two types of the disease: primary TB, which occurs when the immune system can’t fight off the TB bacteria, and reactivation TB, where a dormant TB bacteria revives. Of the two, reactivation TB is more common, making up 90% of all TB cases. It primarily affects the lungs, but can also occur in parts of the body like the stomach, bones, skin, liver, and reproductive system.
According to the World Health Organization (WHO), each year around 8 million people worldwide get active TB and nearly 2 million people die from it. Out of every 10 people infected with TB bacteria, one will likely get an active infection during their lifetime. Although there has been a decrease in global TB rates by 1.5% annually since 2000, the disease remains a serious health concern worldwide. This is especially true in developing countries like India, Pakistan, the Philippines, China, South Africa, Indonesia, and Nigeria, which accounted for 64% of TB-related deaths in 2016, states the WHO.
What Causes Active Tuberculosis (Tuberculosis)?
Tuberculosis is caused by an infection with a type of bacteria called Mycobacterium tuberculosis, often shortened to M. tuberculosis. This bacteria is part of a group that includes four other types that can cause tuberculosis: M. canettii, M. microti, M. bovis, and M. africanum.
M. tuberculosis is a type of bacteria that needs access to air and doesn’t move on its own. It doesn’t form spores, doesn’t break down hydrogen peroxide, and can live within cells. The high fat content in M. tuberculosis makes it unique, giving it resistance to several antibiotics and allowing it to survive in a range of conditions. It also grows a lot slower than other bacteria, taking about 16 to 20 hours to divide, while most bacteria take less than an hour.
This type of bacteria doesn’t react well to a method we usually use to identify bacteria, called a Gram stain, so we can’t classify it as gram-positive or gram-negative bacteria. But sometimes we see weakly positive cells in this test, which we call “ghost cells.” We consider M. tuberculosis to be an “acid-fast” bacteria because it retains some stains even after being treated with acid solutions. To identify it, we usually use the Ziehl-Neelsen or Kinyoun stains, which turn the bacteria bright red and stand out against a blue background.
Humans are so far the only creatures known to naturally host M. tuberculosis, which thrives and reproduces in us. The bacteria primarily spread as an airborne aerosol from a person in the infectious stage of the disease. However, it can also be transmitted through the skin and the gastrointestinal tract, or the digestive system.
Risk Factors and Frequency for Active Tuberculosis (Tuberculosis)
Tuberculosis is a worldwide health issue, with approximately 30% of the global population, equivalent to over two billion people, believed to have contracted the M. tuberculosis bacteria. 2003 saw the highest incidence of tuberculosis. Though the numbers have been declining since then, new cases are still prevalent. Notably, in 2016, most new tuberculosis cases were reported in Asia (about 45%), followed by Africa (nearly 25%). During the same year, it was reported that an estimated 10.4 million people contracted tuberculosis, and approximately 1.7 million passed away due to the disease.
- The presence of tuberculosis is notably affected by geographical region. Regions like India, Sub-Saharan Africa, Micronesia, and Southeast Asia reported the highest rates of the disease (100 or more cases per 100,000 people).
- Intermediate rates were recorded in China, Eastern Europe, Central and South America, and Northern Africa (26 to 100 cases per 100,000 people).
- Conversely, the lowest rates were observed in the United States, Canada, Japan, Western Europe, and Australia (less than 25 cases per 100,000 people).
Though 90% to 95% of people infected with M. tuberculosis don’t develop active disease and remain symptom-free, 5% to 10% do develop the disease. For instance, this led to around 8.6 million active tuberculosis cases worldwide in 2012. In the United States, most cases are seen among immigrants. It is common to detect diseases caused by other nontuberculous mycobacteria, especially among patients with susceptible and compromised immune systems. Distinguishing between tuberculosis and illnesses caused by other nontuberculous mycobacteria can be difficult, but it’s critical because treatment methods differ significantly.
Active tuberculosis is most common among young adults globally. However, in developed countries, the disease is most prevalent among older individuals. All adults are at risk of developing active disease, with several factors increasing this risk:
- People co-infected with HIV are 20 to 30 times more likely to develop active tuberculosis.
- Individuals with weakened immune systems, especially those on long-term corticosteroids or anti-TNF medication.
- People with chronic lung diseases.
- Tobacco users.
- Lack of proper nutrition, indicating a higher risk of developing the active disease, links tuberculosis as a significant illness related to poverty.
- Diabetics, who also generally have poorer treatment outcomes.
- Consumers of alcohol, particularly those drinking more than 40 g per day.
- Intravenous drug users.
- Indoor pollution exposure, silicosis, individuals with end-stage renal disease, patients who had intestinal bypass surgery or gastrectomy, and those with chronic malabsorption syndromes.
Signs and Symptoms of Active Tuberculosis (Tuberculosis)
Pulmonary tuberculosis is a disease that primarily affects the lungs, but it can also affect other parts of the body, a condition known as extrapulmonary tuberculosis, seen in 10-42% of patients. Common symptoms of pulmonary tuberculosis include a long-term cough that is often productive and sometimes mixed with blood. Other symptoms include fever, weight loss, swollen lymph nodes, and night sweats. On the other hand, extrapulmonary tuberculosis can affect any body organ and therefore, symptoms may vary.
If healthcare providers highly suspect tuberculosis, they should gather more information from the patient to identify potential risk factors of the disease, such as:
- History of HIV infection – The level of suppression of the immune system can influence the symptoms.
- History of prior tuberculosis treatment
- History of a positive tuberculin skin test result
- Immigration from or travel to an area where tuberculosis is prevalent
- Close contact with a person with active tuberculosis.
The symptoms of secondary tuberculosis, that is, re-activation of a previous infection, are different from primary tuberculosis. While primary tuberculosis often results in cloudiness in the middle and lower fields of the lungs along with swollen lymph nodes in the chest, secondary tuberculosis typically involves the upper lobes of the lungs, causing cloudiness, cavities, or fibrotic scar tissue.
Active tuberculosis can also spread throughout the body, leading to miliary tuberculosis characterized by tiny, seed-like lesions on chest X-ray images. Tuberculosis can spread to various parts of the body like the bowel, spine (known as Pott disease), or the brain (causing tubercular meningitis). Pleural tuberculosis, which affects the lining of the lungs, is considered as a type of extrapulmonary tuberculosis. People with HIV who have a suppressed immune system are at increased risk for extrapulmonary and disseminated tuberculosis.
The physical examination findings depend on which organs are affected. In cases of pulmonary tuberculosis, a patient may have abnormal lung sounds, particularly over the upper lobes or other affected areas. Signs of extrapulmonary tuberculosis can be different and may include:
- Swollen lymph nodes
- Skin lesions
- Fluid accumulation around the lungs
- Neurological deficits
- Confusion or coma
- Inflammation of the eye’s retina
- Collapsing of the spinal vertebra
Testing for Active Tuberculosis (Tuberculosis)
Active tuberculosis is diagnosed by identifying a certain type of bacteria, Mycobacterium tuberculosis complex, in bodily fluids. A person suspected of having tuberculosis could be at risk of spreading it to others, so it’s important to keep them isolated.
The diagnosis starts with a chest X-ray and examining a mucus sample (known as sputum) from your lungs, obtained by coughing. If you can’t produce a sputum sample, a mist of saltwater can be used to help you cough up the mucus. The sputum sample is then tested in several ways.
One such test, the Acid-Fast Bacilli smear (AFB smear), which is quick to conduct but cannot tell us if the bacteria are Mycobacterium tuberculosis or another type of bacteria.
Another approach includes genetic tests, which can identify the TB bacteria rapidly and precisely. These new-generation tests can confirm the TB infection in just a few hours, as opposed to the days or weeks it takes to wait for a traditional culture. This is particularly helpful among patients with weakened immune systems, who might get a false negative. Some of these tests can also detect if the TB bacteria are resistant to multiple drugs. However, one of these tests, named NAAT, cannot be used to rule out lung tuberculosis.
The gold standard for TB diagnosis is the Mycobacterial culture, which involves growing the bacteria. This method can accurately confirm if TB is present and if it’s resistant to drugs. There are two versions: the solid media is cheaper and slower, while the liquid media is pricier but faster and more sensitive.
If all the measures to get a sputum sample fail, a bronchoscopy could be done. This involves a thin, flexible tube inserted into the lungs to collect fluid for testing.
In cases where tuberculosis has spread outside the lungs, a tissue sample can be taken from the affected organ for diagnosis.
Along with these tests, a skin test called the Mantoux test or a blood test called the Interferon Gamma Release Assays can be performed. These are not definitive tests, but they do aid in the diagnosis. The skin test involves injecting a protein under your skin and checking for a reaction 48-72 hours later. However, this can give false positives, especially in people who have been vaccinated against TB.
If tuberculosis is thought to have spread outside the lungs, the process is similar, with the added measure of sampling fluid or tissue from the affected area. The final diagnosis is determined by the presence of the TB bacteria.
Treatment Options for Active Tuberculosis (Tuberculosis)
If a patient is suspected to have active tuberculosis, it’s important to keep them isolated as airborne precautions to prevent the disease from spreading. This involves putting the patient in a negatively pressured room where air is filtered or expelled outside. Anyone having contact with the patient should wear a high-quality mask, like an N-95, to filter out the tuberculosis bacteria. Typically, these precautions last for about 2 to 4 weeks, until three consecutive sputum tests come back negative. However, these safety methods might not be possible or realistic in developing countries where tuberculosis is prevalent.
In treating active tuberculosis, multiple drugs are needed, with an initial intensive phase followed by a continuation phase. It’s important to avoid using just one therapy to prevent the bacteria from developing resistance to antibiotics. The most commonly used treatments include:
* Isoniazid: Combined with vitamin B6 to avoid nerve damage.
* Rifamycin: Patients should undergo liver function tests before and during treatment since rifamycin can harm the liver.
* Ethambutol: Can cause eye problems, so it’s not used in children whose vision cannot be consistently checked.
* Pyrazinamide: Regular liver function tests, chest X-rays, serum uric acids, and sputum cultures need to be made during treatment.
The intensive phase usually involves taking a combination of these four drugs for two months. This is then followed by a continuation phase where only isoniazid and rifampin are used for four more months.
Ideally, treatment should involve directly observed therapy, where a healthcare provider watches a patient take their medication. This method can potentially allow for reducing the number of weekly doses after the first two weeks.
Patients undergoing treatment should have weekly tuberculosis tests until the treatments show positive results of curing the disease.
Other less commonly used treatments exist for cases where the first-line of treatments fails. These can include a variety of medications like specific kinds of aminoglycosides, polypeptides, and fluoroquinolones, among others. In cases where these fail, there are third-line medications available.
Drug-resistant tuberculosis is a significant concern as it makes the disease more difficult to treat. Drug-resistance can vary from resistance to one or two specific drugs, to extensive drug resistance where the bacteria is resistant to both primary treatments and any secondary treatments. Patients with drug-resistant tuberculosis should receive care from an infectious disease expert, as these cases are increasingly common and challenging to treat.
What else can Active Tuberculosis (Tuberculosis) be?
When doctors are trying to diagnose a specific condition, they often have to rule out other similar conditions. For this particular situation, they might consider the following diseases:
- Actinomycosis (a rare infection caused by a type of bacteria)
- Histoplasmosis (an infection that comes from breathing in spores from a fungus found in bird and bat droppings)
- Blastomycosis (a fungal infection that can affect the lungs, skin, and other parts of the body)
- Cat scratch disease (an infection with Bartonella bacteria that is believed to be transmitted by cat scratches and bites)
- Aspergillosis (a fungal infection that mostly affects people with lung diseases or weakened immune system)
- Lung abscess (a pus filled cavity in the lung)
- Nocardiosis (a rare infection that can affect the lungs, skin and brain)
- Lung cancer
These are the health issues that medical professionals would keep in mind while trying to make a correct diagnosis.
What to expect with Active Tuberculosis (Tuberculosis)
If someone has an active tuberculosis infection and doesn’t get proper treatment, about half of these people will die. This risk becomes worse for certain groups, including:
- Young children, especially babies, and elderly patients
- Those who experience delays in treatment or don’t get the right treatment
- Patients who show a considerable spread of the disease through their body as seen on X-ray images
- Patients with serious breathing issues caused by the disease
- People who are using medications or have a disease that weakens their immune system
Possible Complications When Diagnosed with Active Tuberculosis (Tuberculosis)
For people with tuberculosis, complications often occur if they have the mentioned risk factors, or if they do not get the correct or full treatment for their condition. Some of the complications that can come up from active tuberculosis are:
- Vital distress due to breathing problems
- Extensive damage to the lungs
- A pocket of pus in the chest cavity, known as empyema
- Collapsed lung, or pneumothorax
- Tuberculosis spreads to other parts of the body, including the potential for brain inflammation
- Permanent and abnormal widening of air passages in the lungs
- Scarring of the lining of the chest cavity, known as fibrothorax
- A fungus ball, or aspergilloma
- Coughing up blood
Recovery from Active Tuberculosis (Tuberculosis)
All individuals diagnosed with tuberculosis (TB) require consistent monitoring over a long period. This is to confirm that their condition is improving and that they are following the prescribed treatment plan properly. As the treatment for TB is a lengthy process, patients can sometimes struggle to consistently take their medication. Because of this, a pharmacist may oversee the therapy to enforce adherence, a process called direct observation therapy.
Preventing Active Tuberculosis (Tuberculosis)
It’s crucial for patients to understand that treating tuberculosis takes a long time and requires dedication to taking the medication regularly. If there are concerns about a patient’s ability to stick to the regimen, a strategy called “directly observed therapy” may be used. This approach involves having a healthcare professional monitor the patient while they take their medication, which has been shown to yield better results in patients who struggle with adhering to their treatment plan.
Part of this educational process involves informing patients about the potential side effects of the treatment. Patients should be advised to check themselves at least once a month for signs that the medication might be causing harm to their liver. These symptoms include a loss of appetite, vomiting, dark urine, yellowing of the skin or eyes (jaundice), abdominal pain, or unexplained tiredness. If any of these signs appear, the patient should immediately stop taking the medication and get in touch with their healthcare provider.
Women who have just given birth should be aware that they’re at a higher risk of experiencing side effects from the treatment.
