Introduction to Tuberculosis

VDH TB Control and Prevention Program2011

VDH TB Prevention and Control Policies and Procedures Based on USPHS/CDC, ATS, IDSA and Pediatric “Red Book”

guidelines Adapted to address uniquely Virginia issues

The Causative Agent

M. Tuberculosis - the causative agent for tuberculosis

Robert Koch ~ 1886

Mycobacterium tuberculosis

Bacteria A weakly gram positive rod Appears “rough and buff” in standard culture An organism that holds a red stain even in the

presence of acid, i.e. “acid fast” Slow growing

The Mycobacteria

Human pathogens M. tuberculosis complex includes:

M. tb, M. bovis, M. africanum, M. microti, M. canetti

M. leprae NTM – non-tuberculous mycobacteria

Transmission and Pathogenesis of Tuberculosis

Transmission of TB Spread person to person through the air

TB: Airborne Transmission

Person withactive pulmonary TB

Person breathing TB bacteria

TB bacteria airborne

TB Invades and Infects the Body

Effective immuneresponse

Infection limited

Immune responseinsufficient

Active Disease

Hematogenic spread of bacteria

Or Immune response fails

Pathogenesis of TB Infection begins when the inhaled droplets reach the

alveoli of lungs Tubercle bacilli multiply A number of tubercle bacilli enter the bloodstream

and spread throughout the body (lungs, kidneys, brain, bone)

Within 2-10 weeks, the immune system produces an immune response which encapsulates the bacteria, and is detectable with a TST or IGRA blood test

Probability of TB Transmission

Transmission dependent on three factors Infectiousness of the person with TB Host factors of the exposed person Environment in which the transmission occurs

Likelihood of Developing TB Disease

Once infected with tubercle bacilli 10% life time chance that TB disease will develop

Half the risk within the first 2 years Gradually decreasing risk after the first 2 years

90% chance of never developing the disease Other personal health factors can influence risk

HIV infection - single highest risk for progress to active disease, at 10% risk annually

Diabetes – 30% risk over lifetime

Sites of TB Disease

Pulmonary TB (TB of the lungs) – 80-85% of TB cases Potential for transmission – infectious until proven otherwise

Extra-pulmonary TB (outside the lungs) Can occur anywhere in body Typical sites include larynx, lymph nodes, the pleura, brain,

kidneys, bones, or joints Usually not infectious – always rule out pulmonary! Laryngeal TB is extremely contagious - hoarseness

Diagnosis of TB Disease

SymptomsTST or IGRA

CXRBacteriology

Diagnosis of TB Disease: Symptoms

Pulmonary symptoms Cough Pain in the chest

when breathing or coughing

Coughing up sputum or blood

Systemic symptoms Fatigue / malaise Decreased appetite Weight loss Fever Night sweats Other symptoms

specific to the site of the TB disease

Evaluation for TB Disease

Medical History Symptoms of TB Exposure to TB, Hx previous TB infection, or Hx TB disease Risk factors for progression to TB disease

TB skin test or IGRA Chest x-ray or CT Bacteriologic Examination of sputa, including:

Smears (+AFB) MTD or PCR “direct test (RNA based) Culture results “DNA probes” or traditional culture

Diagnosis of TB Disease

Evaluate all patients with symptoms of TB for TB disease, regardless of the patient’s skin test

reaction 1/4 to 1/3 of all active MTB cases have negative TST at onset of treatment

Diagnosis of TB Disease: Chest X-Ray

Check for lung abnormalities suggestive of TB disease

Typical findings may include cavities, infiltrates, effusions, opacities

A chest x-ray does not confirm TB disease A chest x-ray does not rule out active TB in

immune compromised individuals and children

Diagnosis of TB Disease:Bacteriologic Examinations

Sputum collection – those symptomatic or with abnormal chest x-rays consistent with TB, for AFB smear and culture: A series of three samples Spontaneous or induced At least 8 hrs. apart, and one in early AM

All specimens should be cultured, regardless of smear result Smear/stain results in 1 day, culture results take up to 6-8 weeks M.tb can be cultured from any body fluid or tissue Specimen collected depends on the site of potential disease

Direct Tests for TB

MTD – Mycobacterium tuberculosis direct or TB PCR These rapid tests are done directly on raw respiratory

samples; culture growth is not needed Very sensitive on samples with higher smear positivity A negative test does not rule out TB, especially with negative

smear results Does not provide enough evidence to release from isolation

Antituberculosis Drugs Currently in Use in the US

First-line Drugs Isoniazid* Rifampin* Ethambutol* Pyrazinamide* Rifapentine Rifabutin

Second-line Drugs Cycloserine Ethionamide Levofloxacin Moxifloxacin Gatifloxacin P-Aminosalicylic acid Streptomycin Amikacin/kanamycin Capreomycin Linezolid

TB is usually treated for 6 to 9 months.Drug resistant cases can take years to treat.

Latent Infection vs. Active Disease

Latent TB Infection or LTBI Active TB DiseaseTubercle bacilli in the body

Tuberculin skin test reaction or IGRA usually positiveNo symptoms Symptoms such as cough, fever,

weight lossChest x-ray usually normal Chest x-ray usually abnormal

Sputum smears and cultures, if done, are negative

Sputum smears and cultures may be positive

Not infectious Often infectious before treatmentNot a case of TB, but risk for future disease

A current case of TB

LTBI Treatment Regimens

Targeted Tuberculin Testing and Treatment of Latent Tuberculosis Infection

As tuberculosis (TB) disease rates in the United States (U.S.) decrease, finding and treating persons at high risk for latent TB infection (LTBI) has become a priority.

Before Initiating Treatment

Rule out TB disease (i.e., wait for culture result if specimen obtained)

Determine prior history of treatment for LTBI or TB disease

Assess risks and benefits of treatment Determine current and previous drug therapy

Isoniazid Regimens 9-month regimen of isoniazid (INH) is the

preferred regimen (270 doses) 6-month regimen is less effective but may be

used if unable to complete 9 months May be given daily or intermittently (twice

weekly) Use directly observed therapy (DOT) for

intermittent regimen

Rifampin Regimens (1)

Rifampin (RIF) given daily for 4 months is an acceptable alternative when treatment with INH is not feasible.

In situations where RIF cannot be used (e.g., HIV-infected persons receiving protease inhibitors), rifabutin may be substituted.

Rifampin Regimens

RIF daily for 4 months (120 doses within 6 months)

RIF and PZA for 2 months should generally not be offered due to risk of severe adverse events

MMWR August 8, 2003; 52 (31): 735-739

Completion of Therapy

Completion of therapy is based on the total number of doses administered, not on duration alone.

Tuberculosis Control and Prevention – it takes a Team!

Elements of a Tuberculosis Control Program

Clinical Services

CaseManagement Data analysis

Inpatient care

Medical evaluation and follow-up

X-ray

Laboratory

Pharmacy

Social servicesInterpreter/

translatorservices

Home evaluation

HousingIsolation,detention

Contact investigation

Coordination of medical care DOT

Programevaluation &planning

VDH/DDP/TBApr 2006

Epidemiology and Surveillance

HIV testing andcounseling

State TB Control ProgramFederal TB Control ProgramGuidelines

Training

Funding

National surveillance

Non-TB medicalservices

Data collection

State statutes,regulations,policies, guidelines

Consultation on difficult cases

Outbreak Investigation

Training

FundingInformation for public

Technical assistance

QA, QI for case management

Data for national surveillance report

Follow-up/treatment of contacts

Patienteducation

Targeted testing/LTBI treatment

What is Reportable According to VA Regulation?

By medical provider or designee Confirmed or suspected TB disease Positive TST in children under age 4 years

By directors of medical laboratories Positive AFB smears or cultures

The Public Health Nurse – TB Case Management

Education Assure treatment according to national standards Contact investigation Assure treatment adherence and adequate therapy

DOT as international program standard Identify adverse drug reactions Monitor clinical improvement Recognize patient behaviors Develop strategies to problem-solve

Teamwork!! Tuberculosis is suspected, diagnosed, and treated as a

team. Treatment of LTBI prevents future TB disease It takes all of us to get the job done! Know your local TB health department staff and ask

questions! Only with knowledgeable and trained personnel can

tuberculosis be quickly identified and completely managed.