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Education Materials > Publications > Self-Study Modules on TB > Module 6 > Case Studies

Self-Study Modules on Tuberculosis

Module 6: Contact Investigations for Tuberculosis

Answers To Case Studies

6.1. Jung Hu is a 3-year-old child who has been diagnosed with TB meningitis. Jung and his parents immigrated from China one year ago, along with his paternal grandmother. Jung does not have pulmonary or laryngeal TB disease, and a sputum specimen collected by gastric aspirate does not show any acid-fast bacilli (AFB). Jung's TB disease is reported to the health department and he is started on an appropriate TB drug regimen.

  • Should a contact investigation be done with Jung as the index patient? Why or why not?

    A contact investigation should be done whenever an index patient is found to have or is suspected of having infectious TB disease.

    Jung has extrapulmonary disease and has no AFB in his sputum. Moreover, children with TB disease are rarely infectious, so a contact investigation should not be done with Jung as the index patient.

  • Should a source case investigation be done? What would be the purpose of this investigation?

    In this situation a source case investigation may be done to find the person who transmitted TB to Jung. When a child has TB infection or disease, we know that TB was transmitted relatively recently. In Jung's case, he is 3 years old, so he must have been exposed to someone with TB disease during the past 3 years. The person who is the source of this exposure is called the source patient. In this case, the source patient may be a family member or friend (here or in China) with infectious, possibly untreated TB disease. A source case investigation should be conducted to determine

    • Who transmitted M. tuberculosis to Jung
    • Whether this person is still infectious
    • Whether the case of TB in this person was reported to the health department
    • Whether any others (especially young children) were infected by the source patient

6.2. You are a clinical TB case manager at a busy clinic in Smith County. Three new TB cases have been assigned to you. You need to review their charts and assign them to contact investigators.

  1. Mr. Garcia is a 35-year-old agricultural worker diagnosed by a local private physician with extrapulmonary TB of the kidneys. He lives with his wife and 3 children (5 years, 3 years, and 9 months old) in a small, rented house in a rural part of the county. He rides to work every day in a van with 7 other agricultural workers.

  2. Mr. James is a 72-year-old widower who lives alone on the south side of town. He drives himself to the local retirement center 2 miles from his house for bingo and poker four times a week. He was recently evaluated by the retirement center physician because he complained of a productive cough, shortness of breath, fatigue, and weight loss. He is AFB sputum smear-positive and his culture is pending. His chest x-ray shows a cavity in the right upper lobe. He started a four-drug regimen.

  3. Mrs. Osaka is a 25-year-old woman who recently arrived from Japan. She was seen in the Smith County Clinic complaining of shortness of breath, a weak nonproductive cough, fatigue, and weight loss. Her AFB sputum smear was negative and her culture is pending. She lives with her husband and parents in a large apartment off Broadway. She is currently unemployed. She started a four-drug regimen.
  • For which case(s) should a contact investigation be conducted?

    Both Mr. James and Mrs. Osaka should have contact investigations performed.

    Mr. Garcia has extrapulmonary TB so a contact investigation is not needed.

  • How should the case(s) be prioritized in terms of conducting a contact investigation?

    Mr. James is a high priority for a contact investigation. His is more likely to be infectious because he is AFB sputum smear-positive. His chest x-ray reveals a cavity in the right upper lobe, and he has a productive cough.

    Mrs. Osaka is a lower priority for contact investigation because she is AFB sputum smear-negative, and her culture is pending.

    Mr. James, who has positive AFB sputum smears and a productive cough, is much more likely to be infectious than Mrs. Osaka, who has negative AFB sputum smears and a weak unproductive cough.

6.3. Matilda Landers is a 73-year-old resident at the Washington County Nursing Home who has been hospitalized for a serious respiratory illness. She has been reported to the health department as a suspected TB case, and you are the public health worker assigned to conduct a contact investigation. You have conducted a medical record review and found the following information.

    • Site of TB disease: laryngeal TB suspected
    • TB symptoms: hoarseness, cough, fatigue, weight loss
    • Smear results: AFB positive (3+) on 5/23/99
    • Culture results: pending
    • Chest x-ray results: cavity in left upper lobe
    • TB treatment: four-drug regimen begun on 5/24/99

  • What additional information is needed to establish the period of infectiousness? How will you get this information?

    The period of infectiousness is the time period during which a person with TB disease is capable of transmitting M. tuberculosis. Determining the period of infectiousness can help focus the contact investigation efforts on those persons who were exposed while the patient was infectious. There is no universal, well-established method to determine the period of infectiousness. The beginning of the infectious period is usually estimated by determining the date of onset of the patient's symptoms (especially coughing). Ms. Landers should be asked to estimate the date her symptoms began. The clinician caring for Ms. Landers or the nursing home staff may also provide information about the patient's infectiousness; if a baseline skin test or chest x-ray was performed when Ms. Landers entered the home, this may be helpful.

    The period of infectiousness ends when all the following criteria are met:

    • Symptoms have improved
    • The patient has been receiving adequate treatment for at least 2 to 3 weeks
    • The patient has had three consecutive negative sputum smears from sputum collected on different days

  • What other information will you ask for when you conduct a patient interview with Ms. Landers?

    For the contact investigation, there are three main reasons to interview Ms. Landers:

    • To find out more about her symptoms to help determine the period of infectiousness
    • To find out places where she spent time while she was infectious
    • To identify her contacts, get the contacts' addresses (if available), and find out how often and how long the contacts were exposed to Ms. Landers while she was infectious

    The health care worker should explain the goals of the contact investigation and why it is important to know the names of contacts, whether fellow residents, staff, or visitors. If she may have been infectious before entering the home, Ms. Landers may need to identify contacts at a former residence. Ms. Landers should be told about her right to privacy and the measures that will be taken to maintain confidentiality. In addition, the interview is a good opportunity for the public health worker to get to know Ms. Landers, educate her about TB, look for factors that may affect her adherence to treatment, and arrange follow-up visits with the health department. If Ms. Landers is not mentally able to do the interview, family members, friends, and nursing staff at the home may be asked to help identify contacts.

    When information must be revealed about a case without prior permission in order to protect public health, consultation should be made with a supervisor or TB controller to obtain approval to breach confidentiality. The approval should be documented in the patient record.

6.4. Carmen is a 24-year-old TB patient. She was recently diagnosed with TB by the medical director of the college health center on campus. Carmen is not from the United States. She lives with her aunt and is taking classes at the local college. Susan, the health care worker, is conducting a field investigation. Susan has already conducted a patient interview with Carmen while she was in the hospital. In the interview, Carmen only identified her aunt, as well as three friends from college as contacts. Refer back to Figure 6.5 and use the photo to assist in answering the following question.

  • Based on what is visible in the photo in Figure 6.5, is there evidence of any possible contacts in Carmen's house other than her aunt?

    The health care worker should notice that there are pictures of children and others who were not mentioned in the patient interview. In addition, the health care worker should notice the toys and children's shoes on the floor. There is also a pair of men's boots on the floor. Carmen has not mentioned other contacts in the house. However the pictures, shoes, and toys suggest that there may be other people who live in or visit the house. If additional contacts are identified they should be considered for evaluation.

6.5. A health care worker has just interviewed a 47-year-old TB patient, Derrick Jones. Derrick has had a cough for about 2 months and started treatment for TB disease 3 days ago. He lives alone in a small apartment on 41st Street. He is currently unemployed, but in the past 2 months he has worked the night shift with two other employees at the convenience store on 39th Street. During the day, Derrick goes to friends' apartments nearby or stays in his apartment to watch TV. He often goes to the local bar in his neighborhood with his friends Reggie and Melvin. He usually eats at one of two restaurants--the 39th Street Diner or Susie's Kitchen.

His girlfriend, Tonya, is present at the interview and is aware that Derrick is being treated for TB. Derrick says she spends the night several times a week and often brings her 2-year-old son. When Tonya leaves, Derrick says that another girlfriend, Kelly, has stayed over about 10 times in the past 2 months. Last month, Derrick spent several days at Kelly's house, where she lives with her mother.

  • Based on this information, who are the potential contacts? Which contacts are at higher risk for infection and why?
    • The two coworkers at the convenience store
    • Friends whom Derrick visits at home, and anyone else who lives in their house
    • Reggie, Melvin, and other people who regularly go to the local bar with Derrick
    • The bartender
    • Waiters, waitresses, or friends at the two restaurants
    • Tonya and her son
    • Kelly and her mother

    Close contacts, or people who had close, prolonged exposure to Derrick while he was infectious, are more likely to become infected than contacts who see Derrick less often. Tonya and her son are probably the most at risk because they frequently stay in Derrick's apartment. Kelly and her mother are also at risk because Derrick stayed at their house during the time he was probably infectious. In addition, the friends he spends the most time with -- probably Reggie and Melvin -- would be considered close contacts.

  • While the health care worker is at Derrick's apartment for the interview, what else should be done?

    The health care worker should

    • Note environmental characteristics, such as room size, crowding, and ventilation, to estimate the risk of TB transmission
    • Identify any additional contacts
    • Look for evidence of other contacts who may not be present
    • Interview Tonya and her son, if they are present, and give them tuberculin skin tests. Ask Tonya whether she or her son has had any TB symptoms
    • Educate Derrick and Tonya about how TB is spread, explain why a contact investigation is important, and educate them about testing, treatment, and follow-up for TB infection and TB disease
    • Refer Tonya and her son, if they have TB symptoms, to the health department for a medical evaluation, including sputum collection

6.6. You are in charge of the contact investigation for 35-year-old Hector Gonzalez, who is strongly suspected of having pulmonary TB disease. One week ago, Hector came to the health department complaining of night sweats, a 10-pound weight loss, and a persistent cough that has lasted about a month. His sputum smears were positive for AFB, and he started four-drug treatment for TB disease.

When you interviewed Hector 3 days ago, you found out that he lives with his 32-year-old wife, Mimi; two sons, Luis, 2, and Javier, 4; and his mother-in-law, Alma, 65. Hector's cousin, Henry, has stopped by the house a few times in the past month. Hector informed you that Henry has been HIV positive for 2 years.

Hector rides to work every day with his friend Joe. The ride lasts about half an hour. Hector works in a car assembly plant. About 100 employees work in the main room with Hector, but the room is divided into several sections. There are 20 people in Hector's section, and 4 of these people are assigned to work closely with Hector. Hector eats lunch outside every day with these 4 coworkers.

About twice a week and on weekends, Hector goes to a small neighborhood bar located in the basement of a building. At the bar, Hector spends most of the time talking to the bartender.

  • Which contacts would you consider close contacts?
    • Household members: Mimi, Luis, Javier, Alma
    • Close friend: Joe
    • Four coworkers who work closely with Hector
    • Bartender at the local bar, especially because the bar was small and enclosed in the basement

  • Which contacts would you screen first (the high-priority contacts)?

    All of the close contacts mentioned above, as well as Henry. Although Henry did not have close or frequent exposure to Hector, he is at high risk for developing TB disease because of his HIV infection. Therefore, he should be considered a high-priority contact, and he should be screened along with the first group of contacts.

6.7. The high-priority contacts you identified in Case Study 6.6 for Hector Gonzalez, a patient suspected of having TB disease, were

Household members: Mimi (wife), Luis and Javier (sons), Alma (mother-in-law)

Close friend: Joe

Four coworkers who work closely with Hector

Bartender at the local bar

Hector's cousin Henry, who has HIV infection

These contacts (a total of 11) are being screened by the contact investigation team. Five weeks have passed since the contacts were last exposed to Hector while he was infectious.

  • Which contacts should be evaluated with a medical history and skin test? Which contacts also should be given a chest x-ray?

    Every contact should be screened with a medical history and a Mantoux tuberculin skin test. In addition, Luis (because he is under 4 years of age) and Henry (because he is HIV positive) each should be screened with a chest x-ray. This is because they are at high risk of quickly developing TB disease if infected and may already have TB disease by the time of the contact investigation.

    None of the contacts had TB symptoms. The skin test results were as follows:

    Newly identified positive reaction: Mimi, 32 (11 mm); Javier, 4 (13 mm)

    Negative reaction: Luis, 2 (0 mm); Alma, 65 (3 mm); Joe (3 mm); Henry, HIV+ (0 mm); Coworker A (2 mm); Coworker B (0 mm); Coworker C (0 mm); Coworker D (3 mm); the bartender (0 mm)

  • What follow-up testing and treatment are needed for contacts with a positive skin test reaction?

    Both contacts who have a positive skin test reaction -- Mimi and Javier -- should be given a chest x-ray to rule out the possibility of TB disease. If the chest x-ray is normal, they should complete a full course of treatment for LTBI. If the chest x-ray is abnormal, they should be evaluated for TB disease, including a sputum examination.

  • Should any follow-up testing or treatment be given to contacts with a negative skin test reaction at this time?

    Yes. Because they are at high risk of quickly developing TB disease if infected, Henry and Luis should start treatment for LTBI if their chest x-rays are normal and they have no TB symptoms. Because their last exposure to Hector while he was infectious occurred only 5 weeks ago, their skin-test results may be false-negative reactions. They should be given treatment for LTBI, or window period prophylaxis, until 10 to 12 weeks from their last exposure, when they should have a repeat skin test. If their chest x-rays are abnormal, they should be evaluated for TB disease, including a sputum examination.

  • Which contacts should receive a repeat skin test? When should the repeat test be performed?

    Henry and Luis should be retested 10 to 12 weeks after they were last exposed to Hector. If Luis' second skin test reaction is negative, he can stop taking treatment for LTBI. If his second skin test reaction is positive, Luis should complete a full course of treatment for LTBI. Because he is HIV infected, Henry may be given a complete course of treatment for LTBI, regardless of the second skin test reaction.

    All of the other contacts who have a negative skin test reaction -- Alma, Joe, the bartender, and the four coworkers -- should be retested 10 to 12 weeks after they were last exposed to Hector while he was still infectious. Anyone who has a positive reaction to the second skin test should complete a full course of treatment for LTBI after TB disease has been ruled out.

6.8. The contacts tested in Case Study 6.7 were retested 12 weeks after their last exposure to Hector while he was infectious. Luis and Henry were given window period prophylaxis during the window period. The results of repeat skin testing of contacts with an initial negative reaction are as follows:

      Contact conversions:
    • Coworker A (11 mm)
    • The bartender (10 mm)
    • Luis (8 mm)

      Negative reactions:

    • Alma (4 mm)
    • Joe (2 mm)
    • Henry (0 mm)
    • Coworker B (3 mm)
    • Coworker C (0 mm)
    • Coworker D (4 mm)

      Initial Positive Reaction

    • Mimi (11 mm)
    • Javier (13 mm)

  • What was the infection rate in this group of contacts? Don't forget to include contacts with an initial positive reaction.

    Five contacts had either a newly identified positive skin test reaction on the initial test or a documented conversion on the repeat test; a total of 11 were screened. No contacts had a documented previous skin test.

    [5 ÷ 11] x 100 = 45%

  • The expected infection rate in Hector's community is about 12%. Is there any evidence of TB transmission in the first group of contacts?

    Yes. There are no cases of TB disease, but the infection rate in the group of contacts is higher than the level in the community. Other evidence of recent TB transmission is provided by the three documented skin-test conversions (in Coworker A, the bartender, and Luis). In addition, Luis' infection is evidence of TB transmission because Luis is a young child.

  • Should testing be expanded to the next group of contacts?

    Testing should be expanded to the next group of contacts because there is evidence of recent TB transmission. This should have been done as soon as there was evidence that transmission had occurred (for example, when Javier, a young child, had a positive skin test reaction). The next group of contacts screened should include

    • People who work in the same section with Hector at the plant (other than the four who were already tested)
    • People who go to the neighborhood bar regularly
    • If there is evidence of transmission in this group of contacts, testing should be expanded to include the 100 people in the plant's main room and other identified contacts with a similar level of exposure.

    If there is evidence of transmission in this group of contacts, testing should be expanded to include the 100 people in the plant's main room and other identified contacts with a similar level of exposure.


Released October 2008
Centers for Disease Control and Prevention
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