HIV/STD/TB Program

Public Health Division

TB Contact Investigation

Heidi Behm, RN, MPH

TB Controller/Nurse Consultant

Objectives

• Determine if a TB case is infectious

• Develop strategies for determining how infectious a TB case is

• Be able to assess the risk for transmission

• Understand the infectious period and how to apply it

• Develop some strategies for prioritizing contacts

• Know how to evaluate a TB contact

• Understand when a contact investigation should be expanded

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Warning!

• This is a brief overview only – not enough time to cover all situations!

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What is Done in a Contact Investigation

• Identify people who were exposed to someone

with infectious TB disease

• Evaluate these people for latent TB infection (LTBI) and TB

disease

• Provide appropriate treatment for those with LTBI and TB disease

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Steps in a Successful

Contact Investigation

• Review medical record

- Characteristics as related to infectiousness

- High risk procedures in hospital?

• Interview patient

• Assess risk for transmission

• Decide how to prioritize contacts

• Evaluate contacts

• Treat and follow-up contacts

• Decide if investigation needs to be expanded

Index Patient and Infectiousness

• Site of disease pulmonary, pleural or laryngeal

• Cough

• Chest x-ray

- Cavitary: most infectious

- Miliary, pleural: not very infectious

but investigation still needed

• Labs

- Smear + and degree of positivity

(1+ to 4+)

- NAAT, PCR, GeneXpert RIF/MTB

- Culture

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Patients who are not infectious (usually)

• Children < 5 y.o. unless they have an “adult” type chest x-ray

(cavitary or infiltrates). Don’t forget adults around kids!

• Extrapulmonary TB unless aerosolization occurs.

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You will need to do a contact investigation if the patient is sputum

smear negative, GeneXpert MTB RIF positive for MTB.

TRUE

FALSE

CLUELESS

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Quiz Time!

Setting Infectious Period

• Per CDC: (http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5415a1.htm)

“…3 months before a TB diagnosis is recommended.”

• Based upon expert opinion.

• TB Program, OHA recommends starting with symptom onset

• May not always be practical if multiple hospitalizations, long illness

or multiple contacts.

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Index Case Interview Checklist

• Household members and frequent visitors

• Places the patient has been since symptoms began

• Work or school

• Leisure or recreation activities

• Description of patient’s daily routine

• Transportation to/from work and type of work

• Daytime/evening/nighttime/weekend activities

• Trips, vacations, holiday activities

• Coworkers, school classmates

• Friends and other social contacts

• Girlfriends or boyfriends and other sexual partners

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Assessing Risk for Transmission

• How infectious is index case? Sputum smear+? Cavitary CXR?

• Length of exposure – a lot or a little?

• Intensity of exposure – example: bronchoscopy, intubation, family

member

• Environment where exposure occurred – large, small, airflow, UV

• Contact characteristics – immunocompromised?

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Immunocompromise

• < 4 years old

• HIV+

• Immunosuppressive drugs (TNF α inhibitor)

• Diabetic

• End stage renal disease (ESRD)

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Another Quiz

A health care worker is diagnosed with pulmonary TB disease. Her

chest x-ray is cavitary, sputum smear+ 3, PCR+ MTB, culture pending.

She worked in the following areas. Which are you most concerned

about? (can pick more than one)

A. Dialysis

B. Med. Surg.

C. Hematology/Oncology

D. Labor & Delivery

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Setting Exposure Limits

• Not a science!

• Use judgment, consider all factors (previous slide)

Suggested exposure limits:

• ≥ 4 cumulative hours in small, poorly ventilated space such as car

or enclosed room

• ≥ 8 cumulative hours in small well-ventilated space such as

apartment

• ≥ 12 cumulative hours in a large space such as classroom or house

• ≥ 50 cumulative hours in large open area such as auditorium

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Other Important Info

• Wait for lab confirmation of MTB to start contact investigation. If

there is not a NAA test (PCR) ordered, send sputum to OSPHL.

• Even if index case does not clinically seem very infectious, test a

small group. CDC recommends contact investigation for:

- pulmonary cases

- laryngeal cases

- pleural cases

- smear negative cases

- clinical cases

• Start with a small manageable group, follow closely and expand if

needed.

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Which situation would most likely result in transmission of MTB?

A. Traveling in a car with a 6 month old with pulmonary TB

B. Bronchoscopy of a 32 y.o. with pulmonary MTB

C. Living in an apartment with 67 y.o. with lymph TB

D. Sitting next to a 32 y.o. with TB meningitis on a plane

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Quiz Time!

Example

• Index case

- 24 y.o. patient

- 6 month history of cough and fever. Weight loss of 10 lbs.

- CXR – infiltrates

- 8/11/2013 sputum, smear+2, PCR MTB+, culture pending

• Hospital admits

- Admit 03/10/13 - 03/11/13. Discharge with antibiotics for

pneumonia.

- No isolation precautions.

- Admit 8/10/2013 - 8/16/2013. Not isolated until 8/12/2013.

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Strategy: Hospital Investigation

GOAL: identify individuals with most exposure

• Focus on 08/10/2013 – 08/12/2013

• Roommates?

• Any high risk procedures performed?

• Anyone immunocompromised?

• Who had most exposure? Assigned RN, physician, etc.

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Evaluation of Contacts

• Include symptom screening and risk factor assessment:

http://public.health.oregon.gov/DiseasesConditions/CommunicableDisease/Tuberculo

sis/Documents/formdoc/LTBIscreeningform.pdf

• Test now with a TB skin test, QuantiFERON or TSPOT.

• Test again 8-10 weeks after the initial exposure with same test type.

• If positive, obtain chest x-ray. If normal and no TB s/s, treat LTBI.

• If previously positive, symptom review. CXR if symptomatic or

immunocompromised. Other?

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Immunocompromised Contacts-

Young Kids• Children < 4 y.o.

• May need window prophylaxis:

Test PA and lateral CXR Treat if normal Test

• Infant? May need entire treatment course

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You can’t

make me take

Rifampin!

Immunocompromised Contacts-

Other Conditions

• HIV

• Dialysis

• Diabetes

• Medication (“biologics” TNF alpha inhibitors- remicade, humira, etc)

• Chemotherapy

• Other

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TB Skin Test

• > 5 mm is a positive result for contacts

• For contact investigations, accept as positive (don’t retest with

IGRA) unless TST is unreadable, etc.

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IGRA

• QuantiFERON or T-Spot

• For contact investigations, accept as positive. Don’t retest unless

indeterminate.

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When to Expand an Investigation

• A secondary case of TB disease is diagnosed

- Need a new contact investigation around that person

- Try to determine direction of transmission using genotyping (WGS)

• There are young children newly diagnosed with LTBI

• A high infection rate among contacts

- Determine infection rate and compare to expected rate for a similar

population. NHANES results are useful for this:

http://www.ncbi.nlm.nih.gov/pubmed/17989346

• Conversions among contacts

- From hire if healthcare facility or between baseline and 8-10 weeks

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Why is special follow-up needed for young children or

immunocompromised contacts? HINT: pick 3!

A. They are more likely to get MDR TB

B. The TB skin test and IGRA might be falsely negative

C. They are more likely to develop TB disease if exposed

D. They are less likely to take TB medications

E. The chest x-ray might be hard to interpret

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Quiz Time!

Questions?

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