TB the basics. (Dr) Margaret (DHA) and John (INZ)

TB the basics (Dr) Margaret (DHA) and John (INZ)

Question 1 The scientist who discovered M. tuberculosis was: A: Louis Pasteur B: Robert Koch C: Jean-Antoine Villemin D: Calmette and Guerin

Question 2 How many people are infected with TB bacilli A. 10 million B. 100 million C. 1 billion D. More than 1 billion

How long has TB been infecting humans? TB disease has been found in the mummies of ancient Egyptians and Andean Indians Global problem for thousands of years Consumption, white plague, Captain of the men of death!

What is TB? Beneath a microscope, it has a long rod-like shape or bacillus The thick waxy cell wall allows the bacteria to spread through the air in water droplets TB bacilli stained bright red using the Ziehl-Neelson stain (image copyright Dennis Kunkel Microscopy, Inc.)

How is TB transmitted? TB is transmitted through the air TB bacteria are coughed up from the lungs of an infected person into the air Once the TB bacteria are inhaled, they push their way into the lungs

Question 3 TB is contagious and spreads through the air; if not treated, each person with active TB infects on average; A. less than 1 person a year B. 1 to 5 people each year C. 5 to 10 people each year D. 10 to 15 people each year

Not all TB infections lead to TB disease Latent TB infection (aka LTBI) Contained by immune response asymptomatic Non-infectious Lifetime risk of infected persons with normal immunity developing active TB roughly 10% Active TB disease Active bacterial replication May be symptomatic May be infectious = LTBI active TB = LTBI (Mx +ve)

TB Definitions Latent TB infection (LTBI) TB bacilli live dormant inside the lung, but do not cause destruction of organs No signs or symptoms of disease Not infectious TB disease TB bacilli progressively invade and damage a part(s) of the body Signs and symptoms of disease appear Can be infectious

What is the risk of LBTI progressing to active disease?

Factors increasing risk of tuberculosis Infectiousness of the source case Smear positive > smear negative Intensity of exposure Increased duration of exposure Closer contact with patient in a closed environment Greater susceptibility of the host Malnourishment, low CD4 count, diabetes, chronic kidney disease, smoking, alcohol, medications Increased virulence of the bacteria (e.g. Beijing) 1 Loudon RG, Spohn SK: Cough frequency and infectivity in patients with pulmonary tuberculosis. Am Rev Respir Dis 1969; 99:109-111.

Reactivation of TB Most likely in first 2 years after primary infection Increased risk in immunocompromised (>35 years age ++) Risk highest in those > 5 years age 5-10% lifetime risk Young age Fibrotic lung lesions Post-Transplantation Increased risk in Recent infection Immuno-suppressive therapy * HIV infection Malnutrition Chronic Renal Failure Resettlement (risk persists up to 5 yrs) Diabetes Silicosis

What happens during active TB disease? Active TB disease may occur in the lungs Lungs Pleura Central nervous system Lymphatic system Genitourinary systems Bones and joints Disseminated (miliary TB) Pulmonary TB is the most common form of TB disease and is the infectious form Extrapulmonary TB occurs in up to 40% of TB cases.

Definitions: Patients with TB Pulmonary TB (PTB) Disease involves the lung tissue Smear-positive: visible TB bacilli in sputum, very infectious Smear-negative: no visible TB bacilli in sputum, less infectious Extra-pulmonary TB (EPTB) Disease involving an organ other than the lung, includes pleural TB Not infectious unless also have pulmonary TB Will have positive TST or IGRA

What are symptoms of TB disease? Cough: lasting more than 2 weeks may be productive may be blood stained (21-29%) unexplained Fever (15-52%) Night-time sweats Breathlessness Weight loss (43 57%) Loss of appetite Malaise or fatigue (58%) Due to direct damage Due to general infection and immune response

TB Basics Summary Caused by Mycobacterium tuberculosis Transmitted through the air Infection can cause latent TB or progress to active TB Active TB can be pulmonary or extra-pulmonary Pulmonary TB can be smear positive or smear negative You need to ask and look for TB

TB and Migration

Question 5 In what parts of the Immigration medical examination are you screening migrants for TB? A. History B. Examination C. Chest x-ray D. Blood tests E. A, B and C

Migrants and TB Country Year % overseas born Rate in country born Rate in o/s born (/100K) New Zealand 1995 47.5% 2005 76.3% 3.7 31.3 (8.4x) Australia 1994 66.4% 2010 90.1% 0.7 24.2 (34.6x) Canada 1994 57% 2010 67% 0.7 14.2 (20.3x) UK 1998 45% 2010 73% 4 82 (20.5x) USA 1993 29% 2012 63% 1.4 14.2 (10.1x)

Case 1 30 year old male From China History normal Examination normal Blood tests normal What do you think of the chest x-ray? What would you do?

Think TB Investigation Sputum collection Transport Laboratory Management DOTs Specialist/specialist reports

Diagnosis X-ray is how we screen applicants for TB Migrants who have a positive finding on Chest x-ray will be required to do sputum smears and cultures Extra-pulmonary TB may require tissue samples/culture

Sputum collection Collection - critical importance if the organism is to be isolated 3 x morning sputum samples needed ( 5-10 mls) - consecutive days ideal Must be collected in an appropriate area (outdoors or indoors) and be directly observed and ideally demonstrated Educational instruction video/pamphlets. Clear instructions to client, fasting & appropriate mouth rinsing.

Outdoors

xxx

Indoor specimen collection Negative pressure booths Well-maintained ventilation system Adequate air exchange before next applicant enters booth Provision for direct observation by technologist

Sputum vs Saliva Mucopurulent vs thin, clear (Induced may look like saliva)

Specimen Transport Samples should be transported to the laboratory promptly (noting security / packaging) If not transported within 1 hour, samples should be refrigerated (but not frozen) - 4 to 25 Degree Celsius Specimens received in the laboratory should be processed within 24 hours of receipt

TB laboratory considerations Expertise and equipment Accreditation, training Ensure fraud prevention Number codes or bar codes Provide timely reports Must include smear microscopy, culture, DST, (molecular testing)

Smears Microscopy of specially stained sputum is the main test for diagnosing TB (1-2 days) 6 000 bacilli/1ml: positive smear 10 000 bacilli/1ml: 95% probability positive Sputum smear positive patients are the major source of infection in the community Sputum smear negative patients are responsible for 15-20% of transmission

The Aims of anti-tb Treatment a. To cure the patient of TB b. To prevent death from active TB or its late effects c. To prevent TB relapse or recurrent disease d. To prevent the development of drug resistance e. To decrease TB transmission to others.

Treatment First line TB drugs Rifampicin (R) Isoniazid (H) Ethambutol (E) Pyrazinamide (Z)

Treatment Divided into two phases: Intensive phase (all 4 drugs) for 2-3 months depending on if the patient has been treated before. Continuation phase (rifampicin and isoniazid) for 6 months, depending on whether you have been treated before.

TB Management DOT Specialist referral Follow up: Sputum until negative Serial CXR? Reports Communication/ Active management Notification

Diagnosis Anything missing?

General IME process

Case 1 30 year old male from China. Now 9 months has passed with no treatment and he comes back as he now wants to travel. Now what do you think you will see on the x-ray? He is still pan-susceptible is there anything else you need to think about? Is there anything else you need to do?

Contact Tracing Close contacts of TB patients should also be checked by health staff Active versus passive case finding

What key information does Immigration need? 1. The start and end dates of the TB treatment given. 2. Whether the treatment was performed under DOT or not under DOT and at which facility. 3. The names and dosages of the drugs prescribed. 4. Whether there were any complications with the drugs prescribed and whether there was any need to stop or delay the treatment 5. The body weights of the visa applicant prior to commencement of TB treatment, during treatment and on completion of treatment. 6. The laboratory reports for all sputum smears and cultures during the course of treatment and following completion of treatment (where applicable). Please refer to page 73 of the Australian Panel Member Instruction. In particular: (a) Pan-susceptible (culture positive) infection: two sputum specimens must be collected and submitted for AFB microscopy and mycobacteria culture once a month during therapy, until cultures are negative for two consecutive months. 7. All chest X-rays images and reports during and after the course of TB treatment. 8. The initial first line DST laboratory report including the concentration of isoniazid concentration in the medium used for drug sensitivity testing 9. The laboratory report for second line testing if applicable 10. The laboratory report for HIV testing if available

Question MDR TB: is defined as resistance to A: more than three anti tubercular drugs B: isoniazid and rifampin irrespective of resistance to any other drug C: INH, PZA and Rifampicin D: fluoroquinolones and at least one of the three injectable second-line drugs used to treat TB

Multi-Drug Resistant TB Multi-Drug Resistant (MDR) TB resistant to the 2 most powerful first line anti-tb drugs Rifampicin Isoniazid

Drug Resistant TB Caused by: Poor quality medication Inadequate or erratic treatment Transmission from one person to another

Extensively drug resistant TB - XDR TB MDR-TB that is also resistant to 2/3 most powerful second line TB drugs Difficult to diagnose Time for culture Special laboratories About 10% of MDR TB is XDR Present in every region of the world

Prevention of Tuberculosis 1. Early diagnosis and prompt effective treatment of infectious cases 2. Good infection control 3. Isoniazid preventive therapy 4. Other factors better housing, nutrition, alcohol reduction.