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
- 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
- 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.
- 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.
- 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.
- 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
Both Mr. James and Mrs. Osaka should have contact investigations
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
- 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
- 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
- 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
- Refer Tonya and her son, if they have TB symptoms, to the
health department for a medical evaluation, including sputum
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
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
6.7. The high-priority contacts you identified in Case
Study 6.6 for Hector Gonzalez, a patient suspected of having TB
Household members: Mimi (wife), Luis and Javier (sons),
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
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
- 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:
- 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
- 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.