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TB Contact Investigation Module 15 – March 2010. Project Partners Funded by the Health Resources and Services Administration (HRSA)

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Presentation on theme: "TB Contact Investigation Module 15 – March 2010. Project Partners Funded by the Health Resources and Services Administration (HRSA)"— Presentation transcript:

1 TB Contact Investigation Module 15 – March 2010

2 Project Partners Funded by the Health Resources and Services Administration (HRSA)

3 Overview:  Value (yield) of contact evaluation  Clinical factors influencing transmission  Evaluating contacts and determining priorities  Vulnerable contacts  Treatment of infected contacts Module Overview International Standards 18 and 19

4 Learning Objectives At the end of this presentation participants will be able to:  Describe the criteria used and method for determining an infectious period  Evaluate the risk of transmission based on the clinical extent of disease and diagnostic tests  Determine who among contacts is at greatest risk should infection occur  Identify and evaluate contacts who are at increased risk for TB infection

5 Definitions  Case – a particular instance of disease (e.g., TB). A case is detected, documented and reported  Index case – the first person who presents for evaluation as a confirmed or suspected case of tuberculosis  Source case – the case or person that was the original source of infection for secondary cases or contacts

6 Definitions (2)  Contact –someone who is at risk for acquiring M. tuberculosis infection by sharing airspace with an index case  Converter – a person whose test result for M. tuberculosis has changed from negative (uninfected) to positive (infected)  Window period – refers to the interval between infection and detectable reactivity to the tuberculin skin test (TST)

7 Why do we do TB contact investigations (CI)?

8 Remember!! Every TB Case Began as a TB Contact Contact investigation helps to:  Identify additional TB cases  Identify persons with latent TB infection  Prevent the further spread of TB  Save someone’s life TB Index Case TB Case TB Contacts TB Cases

9 ISTC Standard 18 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 CI 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

10 ISTC Standard 18 (2) The highest priority contacts for evaluation are:  Persons with TB symptoms  Children aged <5 years  Contacts with known or suspected compromised immune systems, particularly HIV infection  Contacts of patients with MDR/XDR tuberculosis  Other close contacts are a lower priority group

11 Standards for Public Health

12 Systematic Review of Contact Investigations  Yield for all active TB among household contacts was 4.5%  Pooled yield for confirmed TB among household contacts was 2.3%  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 2007

13 Morrison J, et al. Lancet ID 2008;8(6) Yield: Active TB and LTBI by Age TB 1 LTBI 2 Children < 5 years1230.4 5 –141747.9 Adults1564.6 1 Number needed to evaluate to find 1 case of TB 2 % of examined contacts with latent TB infection

14 TB Contact Investigation Steps 1.Decide whether to initiate a contact investigation 2.Interview the index case 3.Examine sites of transmission 4.Prioritize contacts 5.Locate and evaluate contacts 6.Treat and follow-up contacts 7.Evaluate contact investigation activities

15 Step 1: Decide if a CI should be initiated To make this decision, you will be assessing for:  Evidence that the index case may be infectious  Presence of vulnerable contacts Those with an immature or weakened immune system

16 Review Medical Record  Site of TB disease  TB symptoms and approximate date of onset  Test results Sputum AFB smear and culture results  Including dates of specimen collection Chest X-ray results and date  TB treatment (medications, dosage, and date treatment was started)  Method of treatment administration DOT or self-administered

17 Assessing Infectiousness  High degree of infectiousness Sputum smear-positive pulmonary TB (PTB) Symptomatic with cough Cavitation on chest radiograph (correlates with positive smear) Laryngeal tuberculosis  Lesser degree of infectiousness Sputum smear-negative, culture-positive PTB Minimal if any cough Lesser radiographic extent of disease Extrapulmonary TB

18 Indices of Infectiousness Source-Case Variables Tuberculin Reactors (%) among household contacts Radiographic extent of disease Minimal16.1 Moderately advanced28.3 Far advanced61.5 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 Loudon RG. ARRD 1969;99:109

19 Prevalence of Infection in Contacts 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 Grzybowski S. BIUAT 1975;60:90 Source case status

20 How do we decide to initiate the contact tracing process?

21 Decision to Initiate TB Contact Tracing Site of disease * Acid-fast bacilli; * * Chest radiograph Pulmonary/ laryngeal/ pleural/ miliary AFB * sputum smear positive Contact tracing should always be initiated Non-pulmonary and/or extra pulmonary (pulmonary and laryngeal involvement ruled out) Contact tracing NOT indicated Abnormal CXR NOT consistent with TB Contact tracing should be initiated only in extreme circumstances Abnormal CXR ** non-cavitary consistent with TB Contact tracing should be initiated if sufficient resources Contact tracing should always be initiated Abnormal CXR** indicates cavitary disease or TB culture positive Pulmonary suspect (tests pending, e.g., sputum, cultures) AFB sputum smear-negative

22 Who is Responsible for Conducting TB Contact Investigations? The National TB Program is responsible for ensuring contact tracing occurs and this includes ensuring:  Identification and evaluation of contacts  Treatment of contacts found to have TB disease  Preventive treatment of contacts with TB infection  Monitoring of treatment and adherence to prescribed regimens  A system is in place to assess completion of treatment

23 How Quickly Should a TB Contact Investigation be Carried Out?  Begin as soon as TB is diagnosed or strongly suspected in a patient  Initiate no more that 7 working days after the case is reported to the National TB Program  Contacts should be examined within 14 working days after the index patient has been diagnosed

24 Rationale for Prompt Contact Tracing  Some contacts may develop TB disease very quickly after being exposed to and infected with M. tuberculosis Infants and children <5 years of age HIV-infected or other immunosuppressed  Increases likelihood that all contacts will be found and evaluated

25 Contact Investigation Case Study Part 1

26 Step 2: Interview the Index Case  Conduct a minimum of 2 interviews 1st interview  ≤1 business day of reporting for infectious patients  ≤3 business days for others 2nd interview  1–2 weeks later May need additional interviews

27 TB Interview Goals  Provide appropriate TB education  Identify problems/concerns  Determine period of infectiousness (IP) and where patient spent time during IP  Identify contacts and locating information  Establish contact investigation priorities  Reinforce follow through with treatment plan

28 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 Morrison J, et al. Lancet ID 2008;8(6)

29 Initial Interview Preparation 1.Review TB patient’s medical records 2.Determine interview objective and strategy 3.Arrange interview place and time

30  Introduction  Education  Contact List  Conclusion  Follow-up TB Interview Components

31 Identification of Contacts  Focus on those in the same household but don’t neglect out-of-household contacts  Tailor interview to patient’s 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

32 Determine Infectious Period  The timeframe during which an individual with TB disease is capable of transmitting infection  This timeframe is determined by estimating the duration of the individual’s symptoms, especially coughing  In the absence of symptoms, this timeframe is determined based on the date of diagnosis of TB disease

33 Estimating Onset of Infectious Period Characteristic TB symptoms? AFB sputum smear positive? Cavitary chest radiograph? Recommended minimum beginning of likely period of infectiousness YesNo 3 months before symptom onset or 1 st positive findings consistent with TB disease, whichever is longer Yes Yes or No3 months before symptom onset or 1 st positive findings consistent with TB disease, whichever is longer NoYesYes or No3 months before 1 st positive finding consistent with TB disease No Abnormal, not cavitary 4 weeks before date of diagnosis as a TB suspect or confirmed case SOURCE: Modified from the California Department of Health Services Tuberculosis Control Branch; California Tuberculosis Controllers Association. Contact Investigation Guidelines. Berkley, CA: California Department of Health Services; 1998, p.23.

34 Closing the Infectious Period Infectious period closed when all the following criteria are met:  Effective treatment for ≥ 2 weeks,  Diminished symptoms, and  Bacteriologic response

35 Contact Investigation Case Study Part 2

36 Step 3: Examine Sites of Transmission  Visit the sites where the patient spent time during the infectious period  Components of the field investigation include: Interview, test & provide TB information to contacts Identify additional contacts Assess physical conditions of the setting (room size, ventilation, airflow, etc.)

37 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 Estimating critical exposure duration  Thresholds are highly variable  Exposure duration threshold should be determined by index case characteristics, settings, contact risk factors

38 Step 4: Prioritize Contacts Concentric Circle Approach +  Infectiousness  Exposure intensity  Susceptibility of the contact

39 Prioritizing Contacts  High priority contacts are determined by: 1.Most likely to be infected 2.Most likely to progress to disease if infected Contact Roster

40 Factors for Assigning Priority Infectiousness Environment Freq/duration Consider:  Infectiousness of the TB case  Environment where transmission likely occurred  Frequency, duration and proximity of exposure  Susceptibility factors: Age, immune system status

41 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

42 Contact Investigation Case Study Part 3

43 Step 5: Locate and Evaluate Contacts

44 Initial Assessments of Contacts  Approach to evaluation of contacts may vary depending on local circumstances, resources, and policies  Evaluation: Question contacts about symptoms and evaluate if symptoms are present TST followed by chest X-ray (CXR) for all positive Mantoux (≥5 mm induration) CXR all children < age 5 and any symptomatic or immunocompromised contacts regardless of TST Sputum examinations for all symptomatic contacts and any with CXR abnormalities suggestive of TB

45 Step 6: Treat & Follow-up Contacts 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

46 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

47 ISTC 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 TB infection with isoniazid

48 Treatment for LTBI: Priorities  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)

49 Other Treatment Considerations  “Window-period” prophylaxis – treatment (usually INH) given to high risk contacts with an initial negative TST during the period following last contact until the follow-up TST  Priorities for initiating window-period prophylaxis include: Children <5 years of age Persons with HIV infection  Exposure to drug resistant TB – consult an expert in the management of drug resistant TB

50 Follow-up  All Contacts found to have latent TB infection (LTBI) and started on treatment should receive monthly visit by a nurse or physician  MDR-TB exposure – seek expert consultation; follow-up for 2 years post exposure

51 Contact Investigation Case Study Part 4

52 Step 7: Evaluate C.I. Activities  Management of care and follow up of TB case and contacts  Epidemiologic analysis of the investigation in progress to allow prioritization of program activities and resources  Program evaluation—measure how well objectives are being met

53 Deciding Whether to Expand Testing Evidence of Recent Transmission:  Infection in a child (<5 years of age)  TST converters  Secondary case  TB disease in any contact assigned a low priority

54 Contact Investigation Case Study Part 5

55 Summary: ISTC Standards Covered* Standard 18: 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 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 * Abbreviated versions

56 Summary: ISTC Standards Covered* (2) 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. * Abbreviated versions

57 Summary  Between 4 - 5 % of household contacts of new cases will be found to have active TB and up to 50% may have LTBI  The likelihood of transmission relates directly to the bacillary burden of the index case  Environmental factors also play an important role  Priorities for evaluation include children <5 years of age, persons with HIV infection, and highly exposed contacts  Treatment is indicated for high priority contacts with LTBI and during the “window period”


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