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Contact Evaluation Your name Institution/organization Meeting Date International Standards 18, 19.

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Presentation on theme: "Contact Evaluation Your name Institution/organization Meeting Date International Standards 18, 19."— Presentation transcript:

1 Contact Evaluation Your name Institution/organization Meeting Date International Standards 18, 19

2 ISTC TB Training Modules 2009 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 TB Training Modules 2009 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 Contact Evaluation International Standards 18, 19

4 ISTC TB Training Modules 2009 Standard 18: Contact Evaluation All providers of care for patients with TB should ensure that persons who are in close contact with patients who have infectious TB are evaluated and managed in line with international recommendations. The determination of priorities for contact investigation is based on the likelihood that a contact: 1)Has undiagnosed TB 2)Is at high risk of developing TB if infected 3)Is at risk of having severe TB if the disease develops 4)Is at high risk of having been infected by the index case. (1 of 2)

5 ISTC TB Training Modules 2009 Standard 18: Contact Evaluation The highest priority contacts for evaluation are: Persons with symptoms suggestive of tuberculosis Children aged <5 years Contacts with known or suspected immunocompromise, particularly HIV infection Contacts of patients with MDR/XDR tuberculosis Other close contacts are a lower priority group (2 of 2)

6 ISTC TB Training Modules 2009 Standards for Public Health

7 ISTC TB Training Modules 2009 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 TB Training Modules 2009 % 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 TB Training Modules 2009 Morrison J et al. Lancet ID 2008 Yield: Active TB and LTBI by Age TB 1 LTBI 2 Children < 5 years – All < Adults = % of examined contacts with clinical and confirmed TB 2 = % of examined contacts with latent TB infection

10 ISTC TB Training Modules 2009 Transmission of M.tb

11 ISTC TB Training Modules 2009 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 TB Training Modules 2009 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 TB Training Modules 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 TB Training Modules 2009 Effect of Therapy on M.tb Log cfu Effective multi-drug therapy reduces bacillary load Weeks

15 ISTC TB Training Modules 2009 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 TB Training Modules 2009 Indices of Infectiousness Loudon RG. ARRD 1969;99: 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 Smear +, culture Mean 8-hour overnight cough count < >

17 ISTC TB Training Modules 2009 Prevalence of Infection in Contacts Grzybowski S. BIUAT 1975;60:90 Source Case status Age (yrs) Smear + Culture ? Smear – Culture + Smear – Culture – General Population %6.0%6.5%0.7%

18 ISTC TB Training Modules 2009 Evaluating Contacts & Determining Priorities

19 ISTC TB Training Modules 2009 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 TB Training Modules 2009 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 TB Training Modules 2009 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 TB Training Modules 2009 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 TB Training Modules 2009 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 TB Training Modules 2009 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 TB Training Modules 2009 Priorities in Contact Evaluation Contacts to MDR/XDR cases Prioritize active case-finding to reduce further transmission of drug-resistant disease

26 ISTC TB Training Modules 2009 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

27 ISTC TB Training Modules 2009 Isoniazid Preventive Therapy: 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

28 ISTC TB Training Modules 2009 Isoniazid Preventive Therapy: 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

29 ISTC TB Training Modules 2009 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) Isoniazid Preventive Therapy: Priorities

30 ISTC TB Training Modules 2009 ISTC Standard 19: IPT Children <5 years of age and persons of any age with HIV infection who are close contacts of an infectious index patient and who, after careful evaluation, do not have active tuberculosis, should be treated for presumed latent tuberculosis infection with isoniazid

31 ISTC TB Training Modules 2009 Contact Evaluation 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

32 ISTC TB Training Modules 2009 Contact Evaluation Summary (continued): Priorities for evaluation include children < 5 years of age, persons with HIV infection, contacts of MDR/XDR cases, and highly exposed contacts Treatment of LTBI may be indicated for high priority contacts

33 ISTC TB Training Modules 2009 Summary: ISTC Standards Covered* Standard 18: All providers of care for patients with TB should ensure that persons (especially if symptoms suggestive of TB, children under 5 years of age, persons with HIV infection, and contacts to MDR/XDR) who are in close contact with patients who have infectious TB are evaluated and managed in line with international recommendations. The determination of priorities for contact investigation is based on the likelihood that a contact: 1) has undiagnosed TB; 2) is at high risk of developing TB if infected; 3) is at risk of having severe TB if the disease develops; and 4) is at high risk of having been infected by the index case. *Abbreviated version

34 ISTC TB Training Modules 2009 Summary: ISTC Standards Covered Standard 19: Children < 5 years of age and persons of any age with HIV infection who are close contacts of an infectious index patient and who, after careful evaluation, do not have active tuberculosis, should be treated for presumed latent tuberculosis infection with isoniazid

35 ISTC TB Training Modules 2009 Alternate Slides

36 ISTC TB Training Modules 2009 Purpose of ISTC

37 ISTC TB Training Modules 2009 ISTC: Key Points 21 Standards (revised/renumbered in 2009) 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

38 ISTC TB Training Modules 2009 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

39 ISTC TB Training Modules 2009 Questions

40 ISTC TB Training Modules 2009 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

41 ISTC TB Training Modules 2009 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)

42 ISTC TB Training Modules 2009 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

43 ISTC TB Training Modules 2009 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


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