Introduction to Tuberculosis VDH TB Control and Prevention Program 2011
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
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-tuberculousmycobacteria
Transmission and Pathogenesis of Tuberculosis
Transmission of TB • Spread person to person through the air
TB: Airborne Transmission TB bacteria airborne Person with active pulmonary TB Person breathing TB bacteria
TB Invades and Infects the Body Hematogenic spread of bacteria Effective immune response Infection limited Immune response insufficient Or Immune response fails Active Disease
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 Symptoms TST or IGRA CXR Bacteriology
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.
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.
Elements of a Tuberculosis Control Program X-ray Targeted testing/ LTBI treatment Inpatient care Clinical Services Pharmacy Medical evaluation and follow-up Non-TB medical services Social services Laboratory Interpreter/ translator services HIV testing and counseling Patient education Data collection Coordination of medical care Epidemiology and Surveillance DOT Home evaluation Contact investigation Case Management Outbreak Investigation Data analysis Housing Program evaluation & planning Follow-up/treatment of contacts Isolation, detention QA, QI for case management Consultation on difficult cases Data for national surveillance report Training Federal TB Control Program State TB Control Program Guidelines Information for public State statutes, regulations, policies, guidelines Funding National surveillance Training Technical assistance Funding VDH/DDP/TB Apr 2006
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.