There are individuals who are at a greater riskof developing active TB:1. HIV or immunosuppressed2. Immigration3. Transmission in high-risk environments4. Drug Resistance5. Babies, young children, the elderly and low body weight.6. Substance Abusers
Individuals who are HIV positive orhave other immune deficientconditions (i.e. organtransplants, cancer, rheumatoidarthritis, leukemia, etc.) have agreater risk of developing active TBdisease, if infected.
Foreign-born individuals who havecome from countries with highprevalence of TB, such asAsia, Africa, the Caribbean and LatinAmerica. These individuals may alsolive in medically underservedareas, which further contributes to theincreased risk for TB transmission.
Transmission of TB accelerates inenvironments where there arepersons in close living conditionsand at a higher risk of infection.Such environments includehomeless shelters, prisons, nursinghomes and hospitals.
Multi-drug-resistant tuberculosis (MDR-TB) refers to strains of tuberculosis thatare resistant to Isoniazid andRifampin, the two drugs used to treat TB.Patients who become infected with thesestrains of TB take longer to recover andremain infectious for a longer period, thuspotentially infecting more people.
Babies, young children, the elderlyand low body weight They have weak immune systems.Substance Abusers People who inject illegal drugs.
Recent reports indicate a decline in thenumbers of TB cases annually in the UnitedState Number of TB cases in the US 30000 25000 20000 15000 Number of TB cases in the US 10000 5000 0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010
The decline in cases can be attributed to the following sixfactors:1. Improved laboratory methods to allow prompt identification of TB2. Broader use of drug-susceptibility testing3. Expanded use of preventive therapy in high-risk groups4. Decreased transmission of TB in congregative settings5. Improved follow-up of persons with TB initially reported to the health department6. Increased federal resources for state and local TB- control efforts.
TB bacilli are carried inairborne or dropletparticles from a personwith pulmonary orlaryngeal TB whospread them when theycough, sneeze, sing oryell.
TB infection occurs after prolonged exposureto someone who has the infectious form ofTB. A person has a 50% chance of becominginfected if they spend 8 hours a day for manymonths with a person with the active form ofTB.
The site of initial infection is usually the alveoli of the lungs where macrophages ingest the inhaled TB bacilli.The body’s cells are stimulated and a delayedhypersensitivity occurs. Specialized cells arestimulated that kill the bacilli and wall offinfection, producing grayish capsules calledtubercles.
The TB bacilli are usually confined in thetubercles in an immuno-deficientindividual, the TB bacilli may break out of thetubercle and lead to the “active” form of thedisease.Only 5–10% ofTB infectionsbecome activeTB, most withinthe first year ofinfection.
Latent TB infection: Some of the bacilli remain dormant and viable for many years. Less than 1% of initially infected persons readily progress to active TB. For 5-10% illness develops after an interval of months, years or decadesProgression to active TB is more likely in persons withmedical conditions that result in immune deficiencies.The risk for progression to active disease is markedlyincreased for persons with HIV infection.
For individuals with activeTB, the bacilli will spreadfrom the lungs to other partsof the body, usually thelymph nodes. In 15% of the active TB cases, bacilli will infect other sites in the body such as the skin, bones and reproductive or urinary systems.
Symptoms of the disease include: Weight loss without dieting Loss of appetite (anorexia) Chills Persistent low grade fever Night sweats Swollen glands (usually in the neck) Recurrent, persistent kidney or bladder infections (lasting at least three weeks) Cough with production of bloody sputum Chest pain upon coughing
Persons exhibiting symptoms and suspected ofhaving TB, should be referred for a completemedical evaluation which should include: Medical history Physical examination Mantoux tuberculin skin test Chest x-ray Other appropriate tests
All healthcarepersonnel are to have anegative Mantoux PPDskin test within oneyear beforeemployment or uponhire and then areretested annually.
Is used for screening individuals who are athigh risk for developing TB. The TB skin testis a method of diagnosing TB infection beforethe infection has progressed to the activedisease. A person who becomes infected withTB will show a positive reaction in 2 – 10weeks.
The Mantoux skin test is performed byinjecting 5 units of purified protein derivative(PPD) intradermally (under the skin) into thesurface of the lower forearm. The reaction tothe test should be read by a trained healthcareprofessional 48 – 72 hours after the injection.A negative reaction mustbe read within 72 hoursor the skin test must berepeated.
If the person is infected, a characteristicwelt will form. This welt consists ofhardening in the form of a raised bumpwhere the PPD was placed and may bered in color. The diameter of theinduration is measured to determineinfection status.
This test reduces the likelihood of mistaking aboosted reaction to the skin test rather than a newTB infection. A boosted reaction to the initial skintest can occur, which may either be a falsenegative or a false positive. Therefore a secondskin test is performed 1 -3 weeks later. If theresults of the second skin test are:1. Negative, then the person is considered NOT infected with TB2. Positive and there are no signs and symptoms of TB, then the results are considered a boosted reaction indication the person may have had an infection in the past, but not recently or had a previous BCG vaccinator or other medical reasons.
People who have had a previous positive reaction People who have a current positive reaction to the two step method People who have completed therapy for active TB in the pastThese individuals must show proof of a negative chestx-ray or provide a physician’s statement indicatingthey are free of communicable disease. Thenannually, they are not to have another x-ray, ratherthey are required to complete a TB Screeningform, which is placed in their file instead of having anannual PPD skin test. This individual is never requiredto have another chest x-ray unless they are exposed toTB or display signs or symptoms of TB.
Interferon-Gamma Release Assays (IGRAs) arewhole-blood tests that can aid in diagnosingMycobacterium tuberculosis infection. They do nothelp differentiate latent tuberculosis infection (LTBI)from tuberculosis disease.IGRAs measure a person’s immune reactivity to M.tuberculosis. White blood cells from most personsthat have been infected with M. tuberculosis willrelease interferon-gamma (IFN-g) when mixed withantigens (substances that can produce an immuneresponse) derived from M. tuberculosis.
There are three different classifications ofTuberculin reactions. These vary based upon thefactors listed below:1. >5 mm: this is considered positive for known or suspected HIV patients, close contacts of persons with infectious TB, persons with chest x-rays suggestive of previous TB, and IV drug abusers2. >10 mm: persons not listed above but are known to be of populations at increased risk for having TB3. >15 mm: this is considered positive in persons with no known risk factors
Tuberculosis can beeffectively treatedusing antibiotictherapy.The length of therapy and combination ofantibiotics decided by the physician, basedupon organism antibiotic sensitivity, signs ofimprovement, and patient compliance.
TB bacteria become active (multiplyingin the body) if the immune system cantstop them from growing. When TBbacteria are active, this is called TBdisease. TB disease will make a personsick. People with TB disease may spreadthe bacteria to people with whom theyspend many hours.
Because there are less bacteria in a person withlatent TB infection, treatment is much easier.The medications used to treat latent TBinfection include: isoniazid (INH) rifampin (RIF) rifapentine (RPT)
TB disease can be treated by taking several drugs for 6 to 9months. The first-line anti-TB agents that form the core oftreatment regimens include: isoniazid (INH) rifampin (RIF) ethambutol (EMB) pyrazinamide (PZA)Regimens for treating TB disease have an initial phase of 2months, followed by a choice of several options for the continuationphase of either 4 or 7 months (total of 6 to 9 months fortreatment).It is very important that people who have TB disease finish themedicine, taking the drugs exactly as prescribed. If they stop takingthe drugs too soon, they can become sick again; if they do not takethe drugs correctly, the TB bacteria that are still alive may becomeresistant to those drugs. TB that is resistant to drugs is harder andmore expensive to treat.
The 12-dose regimen adds another effectivetreatment option to the prevention of TB, and is notmeant to replace other preventative treatmentregimens for all patients where the new regimen isnot the best option. Major components of therecommendations for this regimen include: 12 once-weekly doses recommended for otherwise healthy people aged 12 and older Patients should undergo a clinical assessment at least monthlyFor more information, please visit www.cdc.gov/tb
It is especially important that patients completethe prescribed drug therapy regimen in orderto effectively kill all bacilli. Drug-resistance candevelop when medications are taken incorrectlyby either skipping doses or not taking themedication for the prescribed amount of time.
Early identification, isolation andmedical treatment of patients with TB isnecessary to prevent TB transmissionamong patients and healthcarepersonnel. Nurses and physicians whofirst come in contact with patientsshould be trained to askquestions, which will help identifypatients with active TB.
Patients with active TB areplaced in isolation athealthcare facilities.Engineering controls areused in each isolationroom to prevent thespread and reduce theconcentration of infectiousdroplets in the air.
Patients who have active TB will avoid contactwith other patients. Cough inducingprocedures should be avoided. TB isolationmay be discontinued when the patient is: on effective medication for at least a week is improving clinically has 3 consecutive negative sputum tests
Patients placed in TB isolationwill be instructed in proceduresto prevent TB transmission, andthe reasons for their beingplaced in isolation.The door to the room must always be keptclosed. Healthcare workers will be instructedto wear special fit-tested respirators.
The respiratory protection program will include: Medical screening Fit testing TrainingAirborne Precautions are used to prevent thetransmission of infections spread by the airborneroute. These infectious particles are so small thatthey can remain suspended in the air for longperiods of time and carried on air currents. Examplesof infections spread by the airborne route includechickenpox, tuberculosis and measles.
Medical screening is conducted todetermine whether the employee isphysically able to wear a respirator.
A fit testing is used to determine whether therespirator wearer is able to obtain asatisfactory fit.A respirator cannot be wornby healthcare workers withfacial hair that comes betweenthe sealing surface of themask and face, or if facial hairinterferes with valve function.
Training will beprovided topersonnel whoreceive respiratorsand will includeselection, usestorage ofrespirators as wellas their limitations.
If exposed to a potentially infectious patient, those employeeswho are able to receive a Mantoux PPD skin test will be giventhe test. A negative test is to be repeated after 12 weeks. If theresult of the skin test is positive or there are symptoms of TBpresent, the employee may receive one or more of thefollowing: Chest x-ray A BAMT (blood analysis for M. Tuberculosis) Sputum tests Symptom screening Another skin testExposed employees, who have had a previous positive PPD orcannot receive PPD tests, will be examined by aphysician, monitored for symptoms of TB or possibly have aBAMT test, etc.
Healthcare workers with current TB pose a risk to patientsand other personnel while they are infectious. Theseworkers will be restricted from duty until:1. They have received appropriate documented therapy for at least two weeks2. They show clinical improvement3. They have three consecutive negative sputum smears4. They have a stable or improved chest x-rayPersonnel must be cleared to return to work by aphysician.