1) the cause, clinical manifestation, diagnosis and the treatment of T.B test??
2) Discuss PPD skin test and how to do the interpretation of the results??
3) how the policy of using the skin test (PPT) in the USA in different than other contains that use vaccination? And how to control the TB in the USA
1) The cause, clinical manifestation, diagnosis and the treatment of T.B test??
TB infection is caused by the introduction of M tuberculosis into the body during exposure. Infection may result in clearance of the pathogen, latent infection, primary disease, or reactivation of latent infection years later
Its protean manifestations?primary, latent, and reactivated; pulmonary and extrapulmonary—depend on the stage of disease, the strain of M tuberculosis, and the underlying health of the affected persons
Tuberculosis is diagnosed by finding Mycobacterium tuberculosis bacteria in a clinical specimen taken from the patient. While other investigations may strongly suggest tuberculosis as the diagnosis, they cannot confirm it.A complete medical evaluation for tuberculosis (TB) must include a medical history, a physical examination, a chest X-ray and microbiological examination (of sputum or some other appropriate sample). It may also include a tuberculin skin test, other scans and X-rays, surgical biopsy.
Tuberculosis treatment refers to the medical treatment of the infectious disease tuberculosis (TB).
The standard "short" course treatment for TB is isoniazid (along with pyridoxal phosphate to obviate peripheral neuropathy caused by isoniazid), rifampicin (also known as rifampin in the United States), pyrazinamide, and ethambutol for two months, then isoniazid and rifampicin alone for a further four months. The patient is considered to be free of living bacteria after six months (although there is still a relapse rate of up to 7%). For latent tuberculosis, the standard treatment is six to nine months of isoniazid alone.
2) Discuss PPD skin test and how to do the interpretation of the results??
The PPD skin test is a method used to diagnose silent (latent) tuberculosis (TB) infection. PPD stands for purified protein derivative.
How the Test is Performed
You will need two visits to your doctor's office for this test.
At the first visit, the health care provider will clean an area of your skin. You will get a small shot that contains PPD. The needle is gently placed under the top layer of skin, causing a bump (welt) to form. This usually goes away in a few hours.
After 48-72 hours, you must return to your doctor's office. The doctor or nurse will check the area to see if you have had a strong reaction to the test.
How to Prepare for the Test
There is no special preparation for this test.
Tell your health care provider if you have ever had a positive PPD skin test. If so, you should not have a repeat PPD test, except under unusual circumstances.
Tell your doctor if you have a medical condition or if you take certain drugs, such as steroids, that can affect your immune system. These situations may lead to inaccurate test results.
Normal Results
A negative reaction usually means you have never been infected with the bacteria that cause TB.
A negative reaction means the skin where you received the PPD test is not swollen, or the swelling is very small. This measurement is different for children, people with HIV, and other high risk groups.
The PPD skin test is not perfect. Up to 1 in 5 people infected with the bacteria that cause TB may not have a reaction. Also, diseases or medicines that weaken the immune system may cause a false-negative result.
What Abnormal Results Mean
An abnormal (positive) result means you have been infected with the bacteria that cause TB. You may need treatment to lower the risk of the disease coming back (reactivation of the disease).
It is important to note that test results depend on the person being tested.
A small reaction (5 mm of firm swelling at the site) is considered to be positive in people:
Who have HIV
Who have received an organ transplant
Who have a suppressed immune system or are taking steroid therapy (about 15 mg of prednisone per day for 1 month)
Who have been in close contact with a person who has active TB
Who have changes on a chest x-ray that look like past TB
Larger reactions (greater than or equal to 10 mm) are considered positive in:
People with a known negative test in the past 2 years
People with diabetes, kidney failure, or other conditions that increase their chance of getting active TB
Health care workers
Injection drug users
Immigrants who have moved from a country with a high TB rate in the past 5 years
Children under age 4
Infants, children, or adolescents who are exposed to high-risk adults
Students and employees of certain group living settings, such as prisons, nursing homes, and homeless shelters
In people with no known risks of TB, 15 mm or more of firm swelling at the site indicates a positive reaction.
Risks
There is a very small risk of severe redness and swelling of the arm in people who have had a previous positive PPD test and who have the test again. There have also been a few cases of this reaction in people who have not been tested before.
3) How the policy of using the skin test (PPT) in the USA in different than other contains that use vaccination?
Tuberculosis (TB) is a disease that is spread through the air from one person to another. There are two kinds of tests that are used to determine if a person has been infected with TB bacteria: the tuberculin skin test and TB blood tests.
A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria. It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease. Other tests, such as a chest x-ray and a sample of sputum, are needed to see whether the person has TB disease.
Tuberculin skin test: The TB skin test (also called the Mantoux tuberculin skin test) is performed by injecting a small amount of fluid (called tuberculin) into the skin in the lower part of the arm. A person given the tuberculin skin test must return within 48 to 72 hours to have a trained health care worker look for a reaction on the arm. The health care worker will look for a raised, hard area or swelling, and if present, measure its size using a ruler. Redness by itself is not considered part of the reaction.
The skin test result depends on the size of the raised, hard area or swelling. It also depends on the person’s risk of being infected with TB bacteria and the progression to TB disease if infected.
Positive skin test: This means the person’s body was infected with TB bacteria. Additional tests are needed to determine if the person has latent TB infection or TB disease. A health care worker will then provide treatment as needed.
Negative skin test: This means the person’s body did not react to the test, and that latent TB infection or TB disease is not likely.
TB blood tests: TB blood tests (also called interferon-gamma release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB. An IGRA measures how strong a person’s immune system reacts to TB bacteria by testing the person’s blood in a laboratory.
Two IGRAs are approved by the U.S. Food and Drug Administration (FDA) and are available in the United States:
QuantiFERON®–TB Gold In-Tube test (QFT-GIT)
T-SPOT®.TB test (T-Spot)
Positive IGRA: This means that the person has been infected with TB bacteria. Additional tests are needed to determine if the person has latent TB infection or TB disease. A health care worker will then provide treatment as needed.
Negative IGRA: This means that the person’s blood did not react to the test and that latent TB infection or TB disease is not likely.
IGRAs are the preferred method of TB infection testing for the following:
People who have received bacille Calmette–Guérin (BCG). BCG is a vaccine for TB disease.
People who have a difficult time returning for a second appointment to look for a reaction to the TST.
There is no problem with repeated IGRAs.
How to control the TB in the USA?
Four prioritized strategies exist to prevent and control TB in the United States , as follows:
The first strategy is to promptly detect and report persons who have contracted TB. Because the majority of persons with TB receive a diagnosis when they seek medical care for symptoms caused by progression of the disease, health-care providers, particularly those providing primary health care to populations at high risk, are key contributors to the detection of TB cases and to case reporting to the jurisdictional public health agency for surveillance purposes and for facilitating a treatment plan and case-management services.
The second strategy is to protect close contacts of patients with contagious TB from contracting TB infection and disease. Contact evaluation not only identifies persons in the early stages of LTBI, when the risk for disease is greatest , but is also an important tool to detect further cases of TB disease.
The third strategy is to take concerted action to prevent TB among the substantial population of U.S. residents with LTBI. This is accomplished by identifying those at highest risk for progression from latent infection to active TB through targeted testing and administration of a curative course of treatment. Two approaches exist for increasing targeted testing and treatment of LTBI. The first approach is to encourage clinic-based testing of persons who are under a clinician's care for a medical condition, such as human immunodeficiency virus (HIV) infection or diabetes mellitus, who are at risk for progressing from LTBI to active TB . The second approach is to establish specific programs to reach persons who have an increased prevalence of LTBI, an increased risk for developing active disease if LTBI is present, or both .
The fourth strategy is to reduce the rising burden of TB from recent transmission of M. tuberculosis by identifying settings at high risk for transmission and applying effective infection-control measures to reduce the risk. This strategy was used during the 1985--1992 TB resurgence, when disease attributable to recent transmission was an important component of the increase in TB incidence (52--54). TB morbidity attributable to recent spread of M. tuberculosis continues to be a prominent part of the epidemiology of the disease in the United States. Data collected by CDC's National Tuberculosis Genotyping and Surveillance Network at seven sentinel surveillance sites indicate that 44% of M. tuberculosis isolates from persons with newly diagnosed cases of TB were clustered with at least one other intrasite isolate, often representing TB disease associated with recent spread of M. tuberculosis . TB outbreaks are also being reported with greater frequency in correctional facilities , homeless shelters , bars , and newly recognized social settings (e.g., among persons in an East Coast network of gay, transvestite, and transsexual HIV-infected men ; persons frequenting an abandoned junkyard building used for illicit drug use and prostitution ; and dancers in adult entertainment clubs and their contacts, including children).
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