Tuberculosis Control Manual - Louisiana Department Of Health

infection. This risk is higher in infants andtoddlers than in older adolescents andadults. Among those who do not developdisease in the first two years, 3% to 5%may develop active disease later in life. Of those 5% who develop disease withintwo years of being infected, 50% willdevelop disease within one month, 75%will develop disease within three months,and 90% will develop disease within oneyear.Tubercle bacilli may remain viable butdormant within the tissues for years. Theimmunocompetent response inhibitsreplication of tubercle bacilli. However, theimmune system does not have thecapacity to eliminate all tubercle bacilli. Anindividual’s protective response may waneovertime. In some previously infectedindividuals there is a breakdown inresistance to the tubercle bacilli and bacillimultiply. The reasons for this breakdownare unknown. Tubercle bacilli from aremote infection may shift from a dormantstate to multiply and cause disease.Individuals with HIV and tuberculosis coinfection have an 8-10% annual risk ofprogressing to active disease.Tuberculosis should be designated asrecurrent if a patient has previously hadverified tuberculosis, responded totherapy, and was discharged or lost tofollow up for more than 12 months, andagain has active TB disease.The host develops delayed-typehypersensitivity, which is a cell-mediatedreaction to the tubercle bacilli. This isassociated with a TST or IGRA that canbecome positive 2 to 10 weeks afterinfection. Although no definite proof is availableyet, it seems that the reaction ofhypersensitivity plays little role inacquired immunity of TB in humans.Although both immunity andhypersensitivity involve a cellular type ofimmune response, separate Tlymphocyte populations mediateresponses.2.3 Clinical InformationActive TB is an infectious disease thatusually presents with symptoms.However, many patients, even some withextensive disease, have insidioussymptoms they may not recognize orconsider significant. Other patients maybe truly asymptomatic. Patients who areasymptomatic or do not recognize theirsymptoms as symptoms of TB can only beidentified through a history of exposure,an abnormal chest radiograph,confirmation of infection with a skin orblood tuberculosis test, or culturespositive for Mycobacterium tuberculosis.Factors that prevent relatively healthyindividuals from controlling the dividingbacilli are poorly understood. The immuneresponse may be altered: By certain conditions, e.g. HIV, silicosis,diabetes, cancer, diseases associatedwith immunosuppression, malnutrition,etc. By treatment with corticosteroids or otherimmunosuppressant medications. During the first few years of life, duringpuberty and adolescence, and in thepostpartum period for women.Symptomatic patients can becharacterized as having (1) generalizedsystemic signs and symptoms, (2)pulmonary signs and symptoms, (3) signsand symptoms related to other organs, or(4) a combination of these characteristics.Generalized Signs and Symptoms Frequently patients are first aware offatigue, anorexia, weight loss, nightsweats, or low-grade fever thatpersists over weeks or months. Otherpatients present with acute febrileillness, chills, and generalizedinfluenza like symptoms, and medicalattention is not sought until theIn a small percentage of recently infectedpersons, the initial control of tuberclebacilli by the body is inadequate. There isdirect progression of infection to activeprimary disease, with or withoutdissemination outside the lungs to thepleura, meninges, or other organs.4

chills, myalgia, and sweating similarto signs and symptoms of influenza,acute bronchitis, or pneumonia.Physical findings may or may not bepresent; they are non-specific and notdiagnostic of TB. There may be acuterecurrent pain with pleural effusion.Other Organs Signs and Symptoms TB may affect any organ in the body,including genitourinary tract,lymphatic system, bones and joints,meninges, peritoneum, pericardium,larynx, etc. TB in other organs canoccur at all ages. Symptoms of TBdisease of other organs are variableand often similar to the symptoms ofother infections. The severity of thedisease may range from mild to lifethreatening.symptoms fail to resolve. Erythemanodosum may occur rarely with theacute onset of TB. At times nonspecific systemic symptomsassociated with fever of unknownorigin may be the only manifestationof TB. This syndrome can defyintensive diagnostic evaluation at thehospital, and may be resolved onlythrough a systematic evaluation ofdiagnostic studies such as repeatedchest radiographs, biopsies andcultures of specimens formycobacteria from lung, pleura,pericardium, liver, peritoneum, bonemarrow, blood, or even anexploratory laparotomy. In children the onset of TB is usuallyasymptomatic and may be faradvanced before fever and weightloss begin. A productive cough inchildren is extremely rare; obtaininggastric aspirates via gastric washingto support the diagnosis should beconsidered. Miliary TB, also referred to asdisseminated TB, is seen in all agegroups. Patients may be acutely illwith fever, dyspnea, and cyanosis, orbe chronically ill with systemicsymptoms. Miliary TB is recognizedmost often by the diffuse, finelynodular, uniform infiltrates visible onthe chest radiograph. However, feverand systemic signs and symptomsmay antedate the miliary pattern.Pulmonary Signs and Symptoms Typically, there is the gradual onsetof a cough, which slowly progressesover weeks or months to becomemore frequent and associated withthe production of mucoid ormucopurulent sputum. Occasionallythere is recurring dull, aching pain, ortightness in the chest. Hemoptysis isunusual but prompts the seeking ofmedical attention. Dyspnea is alsocommon and usually indicates eitherextensive parenchymal involvement,a massive pleural effusion, pericardialinvolvement or other underlyingcardiopulmonary disease. Some patients present with the acuteonset of productive cough, fever,2.4 Diagnostic MethodsTuberculin Skin TestThe tuberculin skin test (TST) is themost widely available method to indicateTB infection. The tuberculin test isbased on the fact that mycobacterialinfection produces delayed-typehypersensitivity to certain products ofthe organisms contained in cultureextracts called “tuberculin.” This cellmediated or delayed-typehypersensitivity reaction is manifestedby induration in sensitized persons.Such persons are termed “reactors.” Notall reactors are infected with M. tb;infection with mycobacteria other thanthe tuberculosis species may causeweak cross-reactions. The larger thereaction with a given antigenic dose, thehigher the probability that the reaction isspecific for that antigen.Technique Purified Protein Derivative (PPD)Tuberculin stabilized Tween 80 andstandardized by biologic assay to fivetuberculin units (TU) is therecommended antigen. The standardtechnique (Mantoux) is theintradermal injection of 0.1mL ofPPD-tuberculin containing 5 TUintradermally, usually on the volarsurface of the forearm. Aftercleansing the forearm with5

disinfectant, allow the area to drybefore administration. The injection ismade with a short, bluntly beveled,platinum or steel needle with a plastictuberculin syringe. The injectionshould be made just beneath thesurface of the skin, with the needlebevel upward. Inject slowly. Adiscrete pale elevation of the skin (awheal) 6 to 10mm in diameter shouldbe produced when the prescribedmount of fluid (0.1mL) is accuratelyinjected intradermally. Even thoughthe detergent Tween 80 minimizesthe absorption of tubercle-protein,tuberculin should never betransferred from one container toanother, and skin tests should alwaysbe given immediately after thesyringe is filled. Used needles andsyringes should be placed in apuncture resistant container anddisposed of as medical waste. The site of injection should beexamined 48-72 hours after theinjection, the time when theinduration is usually most evident.Large reactions however will beevident up to seven days later. Thereaction should be recorded as thediameter of induration in millimeters,measured transversely to the longaxis of the forearm. Erythema without induration is notconsidered evidence of tuberculosisinfection. However, if the injection issubcutaneous instead of intradermal,as evidenced by the lack of a whealat the time of injection, erythemacould result with little or no indurationand the test should be repeated.Reading a PPD A PPD reading should be read acrossthe arm, in good light, with theforearm slightly flexed at the elbow.The presence or absence ofinduration may be determined byinspection (from a side view againstthe light as well as by direct light) andby palpation of the injection area.Record Results of PPD Record the single reading across thearm in millimeters of induration. Donot record readings as negative or 6positive. Do not record the extent oferythema.Classification of the tuberculinreaction is determined not only bysize of the reaction, but also byclinical and other risk factors.Knowledge of the significance ofspecific sizes of induration is basedon large epidemiologic surveys ofpatients with TB and othermycobacterial diseases.Reaction 0-4mm: Considerednegative in most persons, but doesnot rule out TB infection or disease.Individuals with overwhelming TB,anergy, or incubating infection mayhave a negative PPD.Reaction 5mm: A reaction of 5mm induration is consideredpositive when the patient has a highlikelihood of infection withtuberculosis or has limited ability torespond immunologically. A reactionof 5mm is considered positive in thefollowing groups: High risk contacts of a person withinfectious TB Persons who also have a chestradiograph suggestive of previousTB and who have receivedinadequate or no treatment Persons known or suspected ofhaving HIV Persons who inject drugs andwhose HIV status is unknownReaction 10mm: A reaction 10mm of induration is consideredpositive when a person does notmeet any of the above criteria, buthas other risk factors for TBincluding: Persons who inject drugs and areHIV negative Persons with certain medicalconditions e.g. diabetes mellitus,silicosis, hematologic andreticuloendothelial diseases, endstage renal disease Persons taking prolongedcorticosteroid therapy or otherimmunosuppressive therapy

Transplant recipients Foreign-born persons from areaswith endemic TB Residents of long-term carefacilities Children under four years old Medically underserved, lowincome populations, high-riskethnic groups Locally identified high-prevalencegroups Reaction 15mm: A reaction 15mm of induration is classified aspositive in persons with no known riskfactors for TB. In general, personswith no known risk factors should notbe routinely screened for TB. Recent converters are defined on thebasis of size induration. An increaseof 10mm within a two-year period isclassified as a recent conversion,regardless of age.TST Results in Healthcare Workers(HCWs) In general, recommendations in theprevious sections should be followedwhen interpreting TST results inHCWs. However, the prevalence ofTB in a facility should be consideredwhen choosing the appropriate cutpoint for defining a positive PPDreaction. In facilities where there isessentially no risk of exposure to TB,i.e. facilities that do not care forpatients with active TB disease, aninduration of 15mm may be asuitable cut-point for HCWs with noother risk factors. In facilities whereactive TB patients are cared for, aninduration of 10mm may be asuitable cut-point for HCWs with noother risk factors. A recent conversion in a HCW shouldbe defined as a 10mm increase insize of induration within a two-yearperiod. For HCWs who work in afacility where exposure to TB is highlyunlikely, an increase of 15mm ofinduration over a two-year periodmay be sufficient.Booster Effect This technique is used to establish abaseline reading for the initial skintest of a series of annual skin tests. 7Subsequent tests, if indicated, shouldfollow the usual single test procedure;if a person has a documented skintest results within the past 12 months,the two-step procedure isunnecessary.A person’s reactivity to tuberculinmay wane over time. For example,adults who were infected duringchildhood may have a small reaction,which would be interpreted asnegative. However, the PPD couldboost the hypersensitivity, and thesize of the reaction could be larger ona subsequent test. This boostedreaction may be misinterpreted as apositive PPD test due to newlyacquired infection. Misinterpretationof a boosted reaction as a newlyacquired infection could result inunnecessary investigations oflaboratory and patient records in anattempt to identify the source case.Additionally the unnecessarytreatment of TB infection may occur.The boost effect may occur at anypoint in one’s life, but the likelihoodincreases with age.When PPD testing of adults is to berepeated periodically, such as withHCWs, two-step testing can be usedto reduce the likelihood that aboosted reaction is misinterpreted asnew infection.An individual with an initial tuberculininduration above the reaction cut offpoint for person’s risk group orpreviously documented reactionshould be considered as positive.Two-step tuberculin skin testingshould be utilized in the initial test ofthe series as follows:An individual with an initial tuberculinskin test induration of less than thecut point for the risk group shouldhave a repeat skin test five days tothree weeks after the first test wasgiven. This boosts the first test. If thesecond induration is above the cutpoint for person’s risk group, theresults should be considered as apositive boosted response.Subsequent skin testing in the futureis not indicated and the individual

should receive medical evaluation todiagnose or rule out TB infection ordisease. If the second induration isless than the cut point, it should beconsidered a negative response andsubsequent skin tests should berepeated at appropriate intervals.Tuberculin Availability PPD 5 TU is the only antigen used bythe Louisiana Office of Public Health.Other strengths of PPD may beavailable but are not recommendedfor TB screening. Always check toensure 5TU is used. PPD should be stored in arefrigerator at 2-8ºC when not in use.When protected from heat and light itretains its potency throughout thedate of expiration. Special noteshould be taken of the expiration dateupon receipt of the antigen. All vialsshould be dated and initialed whenopened. Unused antigen should bediscarded 30 days from the dateopened. The multiple puncture tests (Heaf,Tine, Applitest, or Monovacc) are notrecommended, because it is verydifficult to standardize the amount oftuberculin injected. Results of thesetype tests should be verified by anIGRA or TST. Current stateregulations now require the use ofPPD by the Mantoux method or anIGRA if testing for TB is required foremployment purposes.in all situations in which arecommendation is made to use TST asan aid in diagnosing TB infection. TheIGRA is preferred for testing personsfrom groups that traditionally have poorrates of re

Tuberculosis (TB) 2.1 Classifications-Definitions The classification of TB is based on the broad host-parasite relationships as described by exposure history, infection, and disease. The classification system applies to adults and adolescents. Class 0: No TB exposure, Not infected. No history of TB exposure, and no evidence of M. tuberculosis