1. Contact Evaluation Your name Institution/organization Meeting Date International Standard 16

2. ISTC Training Modules 2008 Contact Evaluation Objectives: At the end of this presentation participants will be able to: Describe how Mycobacterium tuberculosis (M.tb) is transmitted Evaluate the risk of transmission based on the clinical extent of disease and diagnostic tests Identify and evaluate contacts who are at increased risk for acquisition of infection Determine who among contacts is at greatest risk should infection occur Make decisions concerning the treatment of latent tuberculosis infection

3. ISTC Training Modules 2008 Contact Evaluation Overview: Value (yield) of contact evaluation Transmission of M.tb Clinical factors influencing transmission Evaluating contacts and determining priorities Vulnerable contacts Treatment of infected contacts

4. ISTC Training Modules 2008 Standard 16: Contact Evaluation All providers of care for patients with tuberculosis should ensure that persons (especially children under 5 years of age and persons with HIV infection) who are in close contact with patients who have infectious tuberculosis are evaluated and managed in line with international recommendations. (1 of 2)

5. ISTC Training Modules 2008 Standard 16: Contact Evaluation Children under 5 years of age and persons with HIV infection who have been in contact with an infectious case should be evaluated for both latent infection with M. tuberculosis and for active tuberculosis. (2 of 2)

6. ISTC Training Modules 2008 Standards for Public Health

7. ISTC Training Modules 2008 Morrison J et al. Lancet ID 2008 % of Contacts with Active TB (with or without positive bacteriology): Systematic Review. Graph compares results of individual studies in low- and middle-income countries. Pooled average of all studies indicated by arrow. pooled estimate Yield of Contact Evaluations: All Active TB On average, 4.4 household contacts were investigated per index case 4.5% of evaluated household contacts will have active TB Therefore, investigation of approximately 5 households yields one active TB case

8. ISTC Training Modules 2008 % Contacts with LTBI: Systematic Review. Graph compares results of individual studies in low- and middle-income countries. Pooled average of all studies marked by arrow. Yield of Contact Evaluations: LTBI LTBI among household contacts Nearly one-half of the household contacts evaluated had LTBI indicated by a positive tuberculin skin test, but a negative evaluation for active TB. Morrison J et al. Lancet ID 2008 pooled estimate

9. ISTC Training Modules 2008 Morrison J et al. Lancet ID 2008 Yield: Active TB and LTBI by Age TB 1 LTBI 2 Children < 5 years8.530.4 5 –146.047.9 All < 157.040.4 Adults6.564.6 1 = % of examined contacts with clinical and confirmed TB 2 = % of examined contacts with latent TB infection

10. ISTC Training Modules 2008 Transmission of M.tb

11. ISTC Training Modules 2008 Transmission of M.tb CASECONTACT Site of TB Cough Bacillary load Treatment Closeness and duration of contact Immune status Previous infection Ventilation Filtration U.V. light Environment Droplet nuclei

12. ISTC Training Modules 2008 Generation of Droplet Nuclei One cough produces 500 droplets The average TB patient generates 75,000 droplets per day before therapy This falls to 25 infectious droplets per day within two weeks of effective therapy

13. ISTC Training Modules 2008 100 µm 5 µm Evaporation Fate of M.tb Aerosols Large droplets settle to the ground quickly Droplets < 100 m fall <1 meter before evaporating to 1-10 mm size Smaller droplets form droplet nuclei of 1-5 µm diameter and can be inhaled and deposited in the distal airspaces Droplet nuclei remain airborne indefinitely

14. ISTC Training Modules 2008 Effect of Therapy on M.tb Log cfu Effective multi-drug therapy reduces bacillary load Weeks 024681012141618202224

15. ISTC Training Modules 2008 Assessing Infectiousness High degree of infectiousness Sputum smear-positive pulmonary TB Symptomatic with cough Cavitation on chest radiograph (correlates with positive smear) Lesser degree of infectiousness Sputum smear-negative, culture positive pulmonary TB Minimal if any cough Lesser radiographic extent of disease Extrapulmonary TB

16. ISTC Training Modules 2008 Indices of Infectiousness Loudon RG. ARRD 1969;99:109-11 Source-Case Variables Tuberculin Reactors (%) among household contacts Radiographic extent of disease Minimal16.1 Moderately advanced28.3 Far advanced (cavitary)61.5 Bacteriologic status Smear –, culture –14.3 Smear –, culture +21.4 Smear +, culture +44.3 Mean 8-hour overnight cough count < 1227.5 12-4831.8 > 4843.9

17. ISTC Training Modules 2008 Prevalence of Infection in Contacts Grzybowski S. BIUAT 1975;60:90 Source case status Age (yrs) Smear + Culture ? Smear – Culture + Smear – Culture – General Population 0-429.1%6.0%6.5%0.7% 5-935.912.46.20.9 10-1439.514.119.12.2 15-1947.018.1 4.2 20-2951.532.943.410.5 30-3959.252.246.221.3 40+61.150.347.938.5

18. ISTC Training Modules 2008 Evaluating Contacts & Determining Priorities

19. ISTC Training Modules 2008 Decisions in Contact Evaluation Deciding to initiate a contact evaluation Investigating the index case and sites of transmission Identifying contacts and assigning priorities Evaluation of contacts Treatment for contacts with latent tuberculosis infection

20. ISTC Training Modules 2008 Circles of Contacts Index case Household Contacts Average 4 – 5/case Out-of-Household Contacts (Work, school, social) Unknown number Uninfected, 2 Infected, 3 Uninfected, 10 Infected, 5

21. ISTC Training Modules 2008 Identification of Contacts Interview newly diagnosed TB patients to identify contacts Focus on those in same household but dont neglect out-of-household contacts Tailor interview to patients circumstances (homeless, congregate living facility, etc.) Determine the circumstances of exposure, and attempt to quantify the closeness and duration Determine if there are other persons within the group of contacts who have symptoms associated with TB

22. ISTC Training Modules 2008 Levels of Exposure Closeness and duration of exposure: Grading exposure settings 1.Size of a car 2.Size of a bedroom 3.Size of a house 4.Larger than a house

23. ISTC Training Modules 2008 Levels of Exposure Estimating critical exposure duration Thresholds are highly variable Exposure duration threshold should be determined by index case characteristics, settings, contact risk factors

24. ISTC Training Modules 2008 Priorities in Contact Evaluation At greatest risk of acquiring infection Close contacts of smear positive index cases Persons with HIV infection (?) Highly exposed persons At greatest risk of active TB Children < 5 years of age Persons with HIV infection Persons with other immunocompromising conditions or therapies

25. ISTC Training Modules 2008 Initial Assessments of Contacts Assessment depends on local circumstances, resources, and policies. Minimal evaluation: Question contacts about symptoms and evaluate if symptoms are present Tuberculin skin test followed by chest radiographs for all positives (either > 5 mm or > 10mm, depending on local policies) Chest radiographs for all children < 5 years of age Sputum examinations for all symptomatic contacts and all with radiographic abnormalities

26. ISTC Training Modules 2008 Treatment for LTBI: Rationale Risk of active tuberculosis is greatest soon after infection occurs Contacts of infectious cases are likely to have been infected recently Treatment of those found to have a positive tuberculin skin test will reduce the likelihood of active tuberculosis

27. ISTC Training Modules 2008 Treatment for LTBI: Evaluation Evaluate all potential LTBI treatment candidates for active TB Identify those who have been treated previously Identify those with contraindications to treatment for LTBI (prior allergic reactions, severe unstable liver disease) Identify co-morbid conditions and other medications being used

28. ISTC Training Modules 2008 Children < 5 years of age Persons with HIV infection Persons with other immunocompromising conditions Close contacts of highly infectious index case Persons with other conditions that increase risk (example: silicosis) Treatment for LTBI: Priorities

29. ISTC Training Modules 2008 Contact Investigation Summary: Between 4 and 5 % of household contacts of new cases will be found to have active TB and 50% will have LTBI The likelihood of transmission relates directly to the bacillary burden of the index case Environmental factors also play an important role

30. ISTC Training Modules 2008 Contact Investigation Summary: Priorities for evaluation include children <5 years of age, persons with HIV infection, and highly exposed contacts Treatment of LTBI may be indicated for high priority contacts

31. ISTC Training Modules 2008 Summary: ISTC Standard Covered Standard 16: All providers of care for patients with tuberculosis should ensure that persons (especially children under 5 years of age and persons with HIV infection) who are in close contact with patients who have infectious tuberculosis are evaluated and managed in line with international recommendations. Children under 5 years of age and persons with HIV infection who have been in contact with an infectious case should be evaluated for both latent infection with M. tuberculosis and for active tuberculosis.

32. ISTC Training Modules 2008 Alternate Slides

33. ISTC Training Modules 2008 Purpose of ISTC

34. ISTC Training Modules 2008 ISTC: Key Points 17 Standards Differ from existing guidelines: standards present what should be done, whereas, guidelines describe how the action is to be accomplished Evidence-based, living document Developed in tandem with Patients Charter for Tuberculosis Care Handbook for using the International Standards for Tuberculosis Care

35. ISTC Training Modules 2008 Audience: all health care practitioners, public and private Scope: diagnosis, treatment, and public health responsibilities; intended to complement local and national guidelines Rationale: sound tuberculosis control requires the effective engagement of all providers in providing high quality care and in collaborating with TB control programs ISTC: Key Points

36. ISTC Training Modules 2008 Questions

37. ISTC Training Modules 2008 Contact Evaluation 1. A 23 year-old school teacher has recently been diagnosed with active pulmonary TB. She is concerned about the risk of transmitting disease to the children she teaches in a small, poorly- ventilated classroom. Aspects of her clinical presentation that would suggest a higher degree of infectious risk include all of the following except: A.Sputum smear positive for M. tuberculosis B.Significant cough symptoms C.Cavitary-disease on chest film D.Extrapulmonary cervical lymphadenitis

38. ISTC Training Modules 2008 Contact Evaluation 2. A 42 year-old man has been diagnosed with smear-positive pulmonary TB. He works five days per week as an accountant in a small office with two other co-workers and lives in an apartment building with his wife and son. Other activities include a 2-hour weekly football game with his teammates outdoors. (Continued)

39. ISTC Training Modules 2008 Contact Evaluation 2. (Cont.) In regards to planning a contact evaluation for this case, lowest priority for assessment would be: A.Assessment of the clinical factors that influence infectious risk, such as the presence and duration of cough symptoms B.Gathering information regarding age, health status (especially risk for HIV), and presence of TB symptoms in any close contacts C.Evaluation of his outdoor football teammates as contacts D.Evaluation of the size and ventilation of the office space, and the amount of contact time between co- workers and the patient

40. ISTC Training Modules 2008 Contact Evaluation 3. Contacts to an infectious pulmonary case of TB found to have latent TB infection (LTBI) who have the highest risks for progression to active TB disease once infected include: A.Children <5 years of age B.Spouses due to the extended duration of exposure C.Persons with HIV infection D.Both A and C