Tuberculosis Quiz: Transmission and Treatment

Tuberculosis Overview

• Tuberculosis (TB) is a bacterial, infectious disease caused by Mycobacterium Tuberculosis complex (including human, bovis, and Africana strains).
• These organisms are also known as tubercle bacilli or acid-fast bacilli (AFB) due to their resistance to acid decolorization during staining.
• TB affects all races, ages, and organs.
• Infection primarily occurs via inhalation of tubercle bacilli through the respiratory system.
• The lungs are the main organ affected.
• An infected individual may not necessarily develop the disease, with the immune system often containing the bacilli.
• Approximately 5-10% of infected individuals develop active TB disease during their lifetime.
• A smear-positive pulmonary TB (PTB) patient can transmit the infection to 10-15 people annually.

Global Impact of Tuberculosis

• Nearly one-third of the global population (about 2 billion people) is infected with Mycobacterium tuberculosis, at risk of developing the disease.
• Over eight million people develop active TB annually, with around two million deaths.
• More than 90% of global TB cases and deaths occur in developing countries, with 75% of cases affecting the most economically productive age group (15-54 years).
• A TB patient loses on average 3-4 months of work time, causing a loss of 20-30% of annual household income.
• Contributing factors to the increasing TB burden include poverty, collapsed health infrastructure, weak national TB control programs, and the impact of HIV.
• Iraq is a middle-burden country, ranking 108 globally and 7th in the Eastern Mediterranean region concerning TB burden size.
• Estimated incidence of TB in Iraq is 45/100,000, with approximately 15,000 new cases annually. Prevalence is 74/100,000 and mortality 3/100,000.

Transmission of Tuberculosis

• TB transmission is primarily airborne.
• Coughing or sneezing by a patient with active TB produces an aerosol of droplets containing bacilli.
• A high number of infectious droplets (3500 during coughing and 1 million during sneezing) are projected into the atmosphere.
• Droplets dry and become light particles but retain live bacilli, remaining suspended in the air.
• Exposure duration and closeness to an infectious patient significantly increase the risk of infection.
• Bacilli can survive for extended periods, especially in enclosed spaces, increasing the risk of exposure.
• Ingestion (e.g., through contaminated unpasteurized milk), although less common, can also be a transmission route.
• Other rare transmission routes include cutaneous, trans-placental, and trans-sexual transmission.

Incubation and Disease Evolution

• The incubation period for primary TB is 3 to 8 weeks.
• Post-primary TB can take up to years to manifest.
• When virulent bacilli penetrate the lung alveoli, alveolar macrophages phagocytose them, enabling bacilli replication.
• The resulting focus (primary focus) of inflammatory cells is a site of tuberculosis-specific caseating necrosis.
• Bacilli and their antigens are transported via the lymphatic system to lymph nodes.
• T-lymphocytes identify the antigens, which triggers the release of lymphokines, leading to macrophage activation and inhibition of bacilli growth.
• The inflammatory tissue in the primary focus is replaced by fibrous scar tissue, isolating and killing the macrophages containing bacilli.
• Some bacilli survive, entering a latent stage, detectable via tuberculin skin tests.
• Before immunity develops, bacilli from the primary focus are disseminated throughout the body, forming secondary foci.

Primary and Secondary Tuberculosis

• Primary TB is primarily pulmonary, though it can also manifest extra-pulmonary (e.g., intestinal).
• The immune response often results in spontaneous healing, tissue fibrosis (scarring), and calcification for 80-90% of infected individuals.
• For 10-20%, immune response is inadequate, leading to active primary TB or disseminated TB.

Suspected Tuberculosis

• The onset of TB is typically insidious. Symptoms develop slowly over several weeks.
• Common symptoms include persistent cough with sputum production, chest pain or dyspnea, and (less often) hemoptysis.
• Systemic symptoms include evening fever (typically around 38°C), significant night sweats, loss of appetite, loss of weight, and general malaise.
• A cough lasting more than 3 weeks that is unresponsive to standard treatment warrants suspicion of TB.

Tuberculosis Case Definition

• A confirmed TB case is diagnosed by bacteriological confirmation (e.g., AFB, culture) or clinical assessment by a medical professional.
• The site of TB disease is significant. Pulmonary TB affects the lungs in over 80% of cases.
• Extra-pulmonary TB involves various organs.
• TB disease severity is determined by bacillary load, extent of the disease, and anatomical site of the infection.

Bacteriological Examination of Sputum

• A smear test is considered positive if AFB is present in at least two sputum samples.
• Positive AFB together with radiographic abnormalities (characteristic of active PTB) requires a full course of anti-TB drugs as determined by a physician.
• Smear-negative TB (PTB): is defined by two sets of sputum samples (at least two weeks apart) that are negative for AFB.
• In addition, the sample exhibits radiographic abnormalities consistent with active PTB and lack of clinical response to broad-spectrum antibiotics (except quinolones).
• Decisions about treatment are made by treating physicians considering these results and full curative course of anti-TB chemotherapy.

Extra-Pulmonary Tuberculosis

• Diagnosis: one culture-positive specimen, or strong clinical evidence of active extra-pulmonary TB, followed by treatment decision.
• Patients with diagnosed pulmonary and extra-pulmonary TB are typically categorized as pulmonary TB cases.

Case Classification by Previous Treatment

• New case: patients with no prior treatment or treatment lasting less than 4 weeks.
• Relapse: occurs when patients previously cured of sputum-positive pulmonary TB become bacteriologically positive again (smear or culture-positive).
• Treatment failure: patients who remain or become sputum-positive 5 months or more after commencement of treatment, or patients who were initially negative but then became positive after the second month of treatment.
• Treatment defaulter: patients who stop treatment or don't adhere to the prescribed schedule for more than 2 months and subsequently present with sputum that is positive for TB.

Management of Tuberculosis

• Chronic cases: patients who become sputum-positive after a fully supervised retreatment course.

Diagnosis of Pulmonary TB in Adults

• A cough lasting more than three weeks in the absence of other clinical conditions is a critical sign for suspicion of pulmonary TB.
• Sputum samples are examined on three consecutive days by looking for AFB using microscopy method.

Radiographic Diagnosis of Pulmonary TB

• Radiographic findings may include nodules (round shadows with well-defined borders), patchy shadows (irregular border infiltration), cavities (characteristic of TB), calcified nodules, satellite abnormalities, and fibrosis.

DOTS Strategy

• Strategy for Directly Observed Treatment, Short-course (DOTS) tuberculosis treatment.
• DOTS requires five conditions for successful implementation: political will of the government, availability of laboratory networks for identifying smear-positive pulmonary TB cases, readily accessible peripheral healthcare centers, reliable drug supply, and an organized surveillance system.

Tuberculosis Treatment

• Anti-TB chemotherapy is the most important treatment strategy.
• The treatment duration and drugs vary depending on the category of TB and patient characteristics.
• The first line standard regimen typically includes 2HRZES + 1HRZE + 5HRE for category I, 2HRZ + 4RH for category III, and second-line regimens for category IV.
• Treatment strategies should follow clearly defined protocols to prevent drug resistance.

Compilations and Special Considerations

• Pregnant women should start or continue TB treatment according to recommended protocols excluding streptomycin due to possible toxicity to the fetus.
• Breastfeeding women can take all anti-TB drugs approved for this purpose.
• Patients with liver disease should not take pyrazinamide as part of their therapy.
• The use of rifampicin or streptomycin for conditions other than mycobacterium is limited to well-considered indications.
• Anti-TB medications can result in mild side effects; severe side-effects require discontinuation and referral to specialists.

Treatment of Contacts

• Children and adults who cough and were in contact with a positive index case (smear-positive pulmonary TB patient) should undergo sputum examination.
• Children under 5 years old with a positive tuberculin test and symptoms indicative of TB should be treated as cases of active TB.
• Those exhibiting no symptoms but with a positive tuberculin reaction need to undergo six-month preventive chemotherapy.
• Preventive chemotherapy (INH) should be considered for children under 1 year of age with mothers having positive TB until completion of three-month treatment period of the mothers where the tuberculin test turns out to be negative.

Patient Assessment

• Clinical assessment is subjective and not reliable for monitoring TB treatment progress; however, the improvement in patient symptoms may provide clues about TB treatment efficacy.
• Bacteriological assessment with sputum smear examination (every month is not necessary) to monitor treatment progress, especially in sputum-positive patients.
• Radiography may provide preliminary information, but changes may not be indicative of treatment effectiveness.

National Tuberculosis Program in Iraq

• Iraq has an estimated population of 32,249,932 people and is divided into 18 governorates.
• The NTP encompasses nationwide TB control program implementation.
• NTP has established four-level organization with specialized centers for training, implementation of national plans, activities supervision, and management.
• Nineteen governorate clinics contribute to diagnosis, registration, and initial treatment of detected TB cases, with referral to higher-level centers if necessary.
• Each health district has a TB Management Unit (TBMU)/District TB Coordinator (DTC) to ensure TB diagnosis and treatment at the local level.
• Primary Health Care Centers (PHCCs) are involved in TB control, with specific roles in the management of patients' treatment intake.

Strategic Directions of the National TB Program

• Political commitment with increased funding.

• Improving the quality and efficiency of primary healthcare facilities for respiratory illnesses.

• Quality-assured bacteriology for case detection.

• Efficient drug supply and management system.

• Strengthening monitoring and evaluation (M&E) systems.

• Scaling up the prevention and management of Drug-Resistant TB (DR-TB).

• Addressing TB/HIV and the needs of poor and vulnerable populations.

• Engaging all care providers, including the public, non-governmental and private sectors.

• Empowering patients and communities to increase demand for TB care and ensure adherence to treatment programs.

• Promoting research to improve TB program performance.

Importance of DOTS

• Curative therapy of patients.
• Prevention of new TB infections.
• Elimination of Multi-drug resistant (MDR) tuberculosis.
• Cost-effective treatment strategy.
• Community-based intervention.
• Increased life expectancy in patients with HIV.
• Improved protection for international travelers.
• Economic stimulation through better health outcomes.
• Proven effectiveness from numerous studies.

10 Reasons to implement DOTS

• Curing the patient
• Preventing new infections
• Eliminating Multi-drug resistant (MDR) tuberculosis.
• Cost-effective treatment strategy.
• Community-based intervention.
• Increased life expectancy in patients with HIV.
• Improved protection for international travelers.
• Economic stimulation through better health outcomes.
• Proven effectiveness from numerous studies.
• Improved control of TB in a population.

Treatment for Special Cases

• Pregnant women: majority of anti-TB medication is safe, excluding streptomycin.
• Breastfeeding women: most anti-TB treatments are compatible with breastfeeding.
• Liver disease: do not include pyrazinamide in the treatment regimen.
• Acute viral hepatitis: combination of streptomycin & ethambutol up to 3 months and then 6 months of INH & Rifampcin.
• Renal failure: 2 HRZ/6 HR is the safest regimen.