Effective TB Interviewing for Contact Investigation: Self-Study Modules
Outbreak Investigation Interviewing
Conducting TB interviews under outbreak circumstances provides a special challenge. While the objectives and communication skills remain the same for all TB interviews, the situations under which outbreak interviews occur are different.
An outbreak is a greater-than-normal or greater-than-expected number of individuals infected or diagnosed with suspected or verified TB in a given period of time, or a particular place, or both. This can occur in a community or larger geographic area or as part of a single contact investigation. In the first situation, routine surveillance provides an opportunity to identify outbreaks, since the greater-than-expected number of cases may not be readily available. Delays in reporting, cases occurring in multiple communities or TB control jurisdictions, and the new occurrence of a large number of latent TB infections, which are not reportable in many areas, make outbreak identification a difficult task.
Outbreaks may be identified by detecting
- A greater-than-expected rate of M. tuberculosis transmission, as defined by health department or institutional standards, e.g., from one index case, through routine interviewing and evaluation of contacts;
- A greater-than-normal rate of skin test conversions as indicated by institutional standards;
- An increase in TB cases noted through surveillance via required reporting of TB suspects and verified cases, and in some instances, latent TB infection; or
- The same strain of TB detected in various locations through analysis of the genetic structure of specific bacteria from multiple patients (restriction fragment length polymorphism [RFLP] analysis).
In any contact investigation, the TB interview is the first step in identifying all contacts at risk of exposure and transmission to others. However, unique challenges in outbreaks can slow this process, including a greater number of interviews and numerous follow-up interviews of the same index patients to gain additional information. Other issues include
- Having multiple index patients; however, these links may not be evident at first as infected patients who are linked to each other;
- Contacts not being linked through the “obvious” and usual settings such as home, work, or school;
- Links that are difficult to establish due to illicit activities;
- Occurrence of TB disease in individuals not required to be interviewed (e.g., extrapulmonary cases). Subsequently, links to a source case and his or her infected contacts may not occur; or
- Index patients’ inability or unwillingness to name contacts and where they can be located.
Most outbreaks are identified after routine TB interview data have been collected. The analysis of the routine interview data to conduct subsequent interviews and re-interviews requires a different approach. However, comparisons of named contacts and places that patients frequent can yield similar data. For example, several persons with TB or infected contacts may commonly mention one person as a priority contact; this individual may be the source case. A follow-up interview with this individual should be done to determine if there are other contacts who have not been identified. Use of a common place to focus the nature of contact identification can assist in identifying other possible priority contacts. Follow-up interviews can occur as information becomes available and is analyzed. The focus of these interviews, however, may be more specific than previous interviews.
Interviewers should be prepared to provide extensive education about outbreaks in a congregate setting. If an outbreak has been detected and additional patients are being interviewed, the interviewer should explain to these patients, as appropriate, about possible media and press attention that may occur in connection with this outbreak. There may also need to be explanations about possible negative attitudes of those being tested, particularly in a workplace, where speculation about the source case (i.e., the index patient) will occur. The interviewer should acknowledge that a breach in confidentiality by others may occur; however, the health department’s dedication to maintaining confidentiality under all circumstances will be maintained.
Commonly identified places should be prioritized and investigated further through a congregate-setting investigation per health department guidelines. Key to these on-site investigations is the identification of additional priority contacts. This is also the procedure in a standard contact investigation in which a congregate-setting investigation would take place. Prioritization entails looking for places having the likelihood of the highest chances for transmission, i.e., where the index patient(s) spent the most time, and where high priority contacts may be.
In an outbreak scenario, individuals identified as priority contacts may also become the subjects of interviews due the high rate of transmission. This will routinely occur if the contact has developed active TB. However, if transmission is high or seems to be unusual for the identified circumstances in the congregate setting, even with infection, not disease, contacts should be interviewed. Interviews of an infected contact should include
- Review of tuberculin skin test result, latent TB infection, and TB disease history. This history will assist in determining whether the contact has been recently infected or not;
- Places in which, and persons with whom, he or she spends prolonged periods of time. This may eventually lead to determining if the contact has been infected by the identified index case or another case;
- Asking who the contact knows who has TB or TB-like symptoms; listing the symptoms should help identify others with TB. If the contact names the index patient, further questioning about the index patient’s whereabouts, lifestyle, and other potential contacts can be explored. However, it is important that this be done without confirming the identity of the index patient. The interviewer can also inquire about any other persons’ whereabouts, symptoms, and lifestyle mentioned during the interview so as not to appear to focus on the index patient; and
- Discussion with the contact about people with whom he or she shares drugs and alcohol, and where, if applicable. Acknowledging the sensitivity of this line of questioning and reiterating confidentiality can assist in obtaining this information.
The purpose of this type of interviewing is to further identify contacts and other places that the index case has not previously mentioned that can provide information for further investigation. This needs to be done without revealing the name of the index patient(s). In order to find out the most accurate information about where transmission occurred, it is critical that both skin test positive and negative contacts be interviewed, if possible. Deciding which contacts should be interviewed can be facilitated through network analysis, discussed in the next section.