What Is Tuberculosis?
Tuberculosis (TB) was the primary cause of death in 2015, with 10.4 million cases and 1.8 million deaths. Individuals infected with tuberculosis are classified as having active tuberculosis disease, marked by the manifestation of clinical symptoms that can affect many organs, or having latent tuberculosis infection, a clinical state without symptoms that are non-transmissible.
While Mycobacterium tuberculosis, which causes tuberculosis, can infect many parts of the body, pulmonary tuberculosis is the most commonly transmitted form. The conventional view of TB infection as a binary condition (either active or latent) has evolved. A contemporary perspective treats TB infection as a spectrum of disease states. While active TB case detection has been a primary focus, recent models emphasize reducing the LTBI reservoir through preventative therapy to meet ambitious public health targets. A vital public health objective is to prevent the advancement of LTBI to active TB disease, as this has the potential to decrease the transmission of tuberculosis significantly. Targeted treatment of those infected and at risk of progressing to active TB disease is an important component of the end TB strategy.
What Is Latent Tuberculosis?
TB bacteria can survive in the body without causing illness. This is known as latent tuberculosis infection. When most people breathe in TB bacteria and become infected, their bodies can fight the bacteria and prevent them from growing.
People who have latent tuberculosis infection:
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There are no symptoms.
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Show a positive TB skin test reaction or a positive TB blood test.
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They do not feel ill.
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Do not spread tuberculosis to others.
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If timely treatment for latent TB infection is not received, they may develop active TB disease.
Many people with latent tuberculosis never develop TB disease. The TB bacteria remain dormant in these people for a lifetime without causing disease. However, in some people, particularly those with a weakened immune system, the bacteria become active, multiply, and cause tuberculosis (TB).
What Are the Signs and Symptoms of Latent Tuberculosis?
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People suffering from LTBI are healthy and do not feel ill.
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They usually have a normal (negative) chest X-ray.
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They have a positive TST (tuberculin skin test) or a positive blood test for tuberculosis.
How Is Latent Tuberculosis Diagnosed?
The effective delivery of preventative therapies depends on an LTBI diagnosis that is sensitive and accurate. Bacterial culture is the standard for detecting active infections, but there is no standard for detecting LTBI. Because the actual pathogen cannot be detected, identifying latent tuberculosis infection involves assessing immune responses to antigens produced by M. tuberculosis.
1. Tuberculin Skin Testing (TST):
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TST, also known as the Mantoux tuberculin skin test, entails injecting a minimal quantity of purified protein derivative, a substance derived from the bacteria responsible for tuberculosis, just beneath the skin.
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The test is usually administered on the forearm. Within 48 to 72 hours, a doctor or a nurse examines the injection site for any observable reactions.
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A positive reaction typically indicates exposure to the tuberculosis bacteria, but it does not distinguish between latent and active infection.
2. Interferon-Gamma Release Assays (IGRAs):
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IGRAs are blood tests designed to quantify interferon-gamma release by white blood cells in response to specific antigens associated with Mycobacterium tuberculosis.
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Like the TST, a positive result suggests exposure to tuberculosis bacteria, and additional clinical and risk assessment is necessary to determine whether it is a latent or active infection.
What Is the Treatment of Latent Tuberculosis?
Several treatment regimens for latent tuberculosis infection are recommended in the United States. Akt4 is a combination medication used in the treatment of active tuberculosis, containing four drugs: Rifampicin, Isoniazid, Pyrazinamide, and Ethambutol. For latent tuberculosis, the focus is usually on a single drug to prevent the development of active disease.
The following medications are used to treat latent tuberculosis infection:
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Isoniazid (INH).
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Rifampin (RIF).
These medications can be taken alone or in combination. The CDC and National Tuberculosis Controllers Association (NTCA) prefer three or four months of rifamycin-based latent TB infection treatment regimens over six or nine months of Isoniazid monotherapy.
Short course regimens include the following:
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Isoniazid, along with Rifapentine, once a week for three months (3HP).
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Four months of Rifampin (4R) daily.
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Three months of Isoniazid plus Rifampin regularly (3HR).
Short-course treatment regimens, such as 3HP and 4R, are more effective, safe, and have higher completion rates than six- to nine-month Isoniazid monotherapy regimens.
If the patient is in contact with someone with drug-resistant tuberculosis, all treatment must be modified. Clinicians should select the appropriate treatment regimen based on the presumed source case's drug susceptibility results (if known), coexisting medical conditions (e.g., HIV), and the potential for drug-drug interactions. If the known source of the TB infection is drug-resistant TB, a consultation with a TB expert is recommended.
What Are the Risk Factors for Latent Tuberculosis?
Close contact with the people listed below raises a person's risk of LTBI:
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People who have active tuberculosis.
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Those who were born traveled or lived in a foreign country.
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Injection drug users, homeless people, and people living with HIV (Human Immunodeficiency Virus) or AIDS (Acquired Immunodeficiency Syndrome) are examples of high-risk groups for tuberculosis transmission.
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People who are at a high risk of contracting tuberculosis, such as those in hospitals, nursing homes, prisons, homeless shelters, or refugee camps.
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People with compromised immune systems, people with certain medical conditions, infants (less than one year of age), and the elderly are more likely than others to develop an active TB disease.
What Is the Difference Between Latent Tuberculosis Between Active Tuberculosis?
If the immune system cannot stop the TB germs from multiplying, they become active. TB illness happens when the TB bacteria are active or multiplying within the body. Those who have tuberculosis are ill. Additionally, they could be able to infect those they interact with daily.
Latent tuberculosis infections frequently do not result in tuberculosis illness. Within weeks of contracting an infection, some patients get tuberculosis before their immune system has a chance to combat the TB germs. Years later, additional people might become ill when their immune systems weaken for other reasons. The chance of contracting tuberculosis (TB) is significantly higher in those with weakened immune systems—particularly those living with HIV—than in those with healthy immune systems.
1. Latent TB:
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The TB germs are dormant in the body.
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Patients feel good and do not have any symptoms.
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TB cannot be spread to other people.
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Only a blood test or a skin test for tuberculosis can identify it.
Treated for three to six months with one or two medications.
2. Active TB:
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Patients are being sickened by living tuberculosis bacteria.
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The patient has symptoms that make the patient feel uncomfortable.
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If TB is present in the lungs, patients can spread it to others.
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If the patient has tuberculosis in their lungs, it is visible on a chest x-ray.
Administered four or more medications for a minimum of six months.
Conclusion:
Untreated LTBI reactivation is a major source of new active TB infections and transmission. It accounts for most new tuberculosis cases in countries with low tuberculosis incidence. To meet the objectives of eliminating tuberculosis, a primary focus includes conducting specific testing for LTBI and providing treatment to marginalized and hard-to-reach populations, as well as those with a heightened risk of tuberculosis reactivation.
