Multiple outbreaks of TB, including those involving MDR TB, have been reported in prisons and jails, particularly among HIV-infected inmates.[22,45,154] The identification of a potentially infectious case of TB in a correctional facility should always provoke a rapid response because of the potential for widespread TB transmission. A prompt public health response in a confined setting can prevent a TB outbreak or contain one that has already begun.[16,21,155]
The overall goal of a TB contact investigation is to interrupt transmission of M. tuberculosis. Ongoing transmission is prevented by 1) identifying, isolating, and treating persons with TB disease (source and secondary-case patients) and 2) identifying infected contacts of the source patient and secondary patients and providing them with a complete course of treatment for LTBI. The contact investigation can serve to educate corrections staff and inmates about the risk, treatment, and prevention of TB in correctional facilities; inform staff and inmates regarding the importance of engaging in recommended TB-control practices and procedures within the correctional system; and emphasize the importance of completion of therapy for persons with TB disease and LTBI.
Because decisions involved in planning and prioritizing contact investigations in correctional facilities are seldom simple, a multidisciplinary team is preferable. Health departments often can help correctional facilities in planning, implementing, and evaluating a TB contact investigation.
Data collection and management is an essential component of a successful investigation.[21,36] It requires a systematic approach to collecting, organizing, and analyzing TB-associated data. As part of the contact investigation, all staff and investigation personnel should adopt a uniform approach. Investigators should have a clear understanding of how a contact is defined and what constitutes an exposure.[156,157,158]
Two correctional information systems are critical to the efficient conduct of a contact investigation: 1) an inmate medical record system containing TST results and other relevant information and 2) an inmate tracking system. The lack of either system can lead to the unnecessary use of costly personnel time and medical evaluation resources (e.g., TSTs and chest radiographs). Without these information systems, facilities also might be forced to implement costly lockdowns and mass screenings.
TB transmission is determined by the characteristics of the source patient and exposed contacts; the circumstances surrounding the exposure itself also determine whether ongoing transmission will occur. The following variables should be accounted for when planning each contact investigation.
Characteristics of the Source Patient. Source patients who have either cavitation on chest radiograph or AFB smear-positive respiratory specimens are substantially more likely to transmit TB than persons who have neither characteristic.[159,160,161,162,163] Delays in TB diagnosis in source patients have also been associated with an increased likelihood of transmission. Nonetheless, substantial variability exists among the infectiousness of a given TB source patient. Although AFB smear status, cavitary disease, and delayed diagnosis increase the likelihood of transmission, certain persons with these characteristics infect few persons, whereas others with none of these characteristics might infect multiple persons. The best measure of the infectiousness of source patients is the documented infection rate among their contacts.
Characteristics of Persons Who Have Been Identified as Contacts. Immunosuppression. HIV infection is the greatest single risk factor for progression to TB disease. Therefore, HIV-infected contacts should receive the highest priority for evaluation of TB infection, even if these persons had shorter duration of exposure than other contacts. Persons receiving prolonged therapy with corticosteroids, chemotherapy for cancer, or other immunosuppressive agents (e.g., TNF-a antagonists) also should be considered high priority for investigation. In addition, persons with end-stage renal disease and diabetes mellitus should be promptly evaluated, because these conditions are associated with compromised immune function.
Age. Young children (i.e., those aged <4 years) are at high risk for rapid development of TB disease, particularly TB meningitis. If an inmate with TB identifies a young child as a community contact, a health department referral should be made immediately.
Exposure Characteristics. Air Volume. The volume of air shared between an infectious TB patient and susceptible contacts is a major determinant of the likelihood of transmission. Infectious particles become more widely distributed as air space increases, rendering them less likely to be inhaled.
Ventilation. Ventilation is another key factor in the risk for airborne transmission of disease. Airborne infectious particles disburse throughout an entire enclosed space; thus, if air is allowed to circulate from the room occupied by an infectious patient into other rooms or central corridors, their occupants also will be exposed. Areas that have 1) confined air systems with little or no ventilation or 2) recirculated air without HEPA filtration have been associated with increased TB transmission.
Duration of Exposure. Although transmission of TB has occurred after brief exposure, the likelihood of infection after exposure to an infectious patient is associated with the frequency and duration of exposure. However, defining what constitutes a substantial duration of exposure for any given contact is difficult. When conducting a contact investigation, priority should be given first to inmates and employees who were most exposed to the source patient.[21,154,162]
The decision to initiate a contact investigation for an inmate or detainee with possible TB is made on a case-by-case basis. Each potential source patient's clinical presentation and opportunities for exposure should be evaluated. Contact investigations should be conducted in the following circumstances:
Suspected or confirmed pulmonary, laryngeal, or pleural TB with cavitary disease on chest radiograph or positive AFB smears (sputum or other respiratory specimens). If the sputum smear is positive and the NAA is negative, TB is unlikely, and a contact investigation typically can be deferred. A negative NAA on an AFB-smear-negative specimen, however, should not influence decisions about the contact investigation.
Suspected or confirmed pulmonary (noncavitary) or pleural TB with negative AFB smears (sputum or other respiratory specimens) and a decision has been made to initiate TB treatment. A more limited initial investigation may be conducted for smear-negative cases.
Contact investigations typically are not indicated for extrapulmonary TB cases (except for laryngeal and pleural TB), unless pulmonary involvement is also diagnosed.
The decision as to whether the facility should conduct a contact investigation should be guided by the probability that an inmate or employee has pulmonary TB. Sputum results for AFB serve as a major determinant. However, in certain patients with pulmonary TB, collecting sputum samples is not feasible. In this circumstance, other types of respiratory specimens (e.g., those from bronchoscopy) may be collected for AFB smear and mycobacterial culture.
No simple formula has been devised for deciding which contacts to screen in a correctional facility contact investigation. However, the investigation should be guided by the following basic principles:
Identified contacts should be stratified by their duration and intensity of exposure to the source patient.
HIV-infected contacts should be classified as the highest priority group for screening and initiation of LTBI therapy, regardless of duration and intensity of exposure.
Identified groups of contacts with the greatest degree of exposure should be screened immediately, followed by repeat testing at 8-10 weeks if the initial TST or QFT-G is negative.
The infection rate should be calculated to assess the level of TB transmission.
Decisions to expand the contact investigation to groups with less exposure should be made on the basis of the calculated infection rate. If no evidence of transmission is observed, the investigation should not be expanded. If transmission is occurring, the investigation should be expanded incrementally to groups with less exposure. When the group screened shows minimal or no evidence of transmission, the contact investigation should not be expanded further.
Corrections and medical staff should be included in the contact investigation depending on their exposure risks.
Ideally, decisions about structuring the contact investigation should be made collaboratively with the contact investigation team that includes input from the state or local health department. For certain investigations, screening a convenience sample before expanding the investigation is prudent. For example, in jail investigations, multiple contacts might already have been released, rendering those who remain incarcerated the only available group for screening. If a substantial number of high priority contacts cannot be evaluated fully, a wider contact investigation should be considered.
The investigation should focus on identifying the contacts at highest risk for transmission, screening them completely, and providing a full course of LTBI treatment for persons demonstrated to be infected. In general, because wide-scale investigations divert attention away from the high priority activities necessary to interrupt transmission in the facility, mass screening of all persons who had any contact with the source patient should be avoided. Rarely is a person so infectious that wide-scale expansion of the contact investigation is necessary or beneficial.
Appropriate medical evaluation depends on both the immunologic status (e.g., HIV infection) of the contact and previous TST or QFT-G results. Adequate knowledge of these data is possible only through use of a medical record system that is complete, up-to-date, and reliable with regard to TST or QFT-G status, testing date, and documentation of the reading in millimeters (for TST). Without an adequate medical record system (and therefore definitive information regarding prior TST or QFT-G results), the true infection and transmission rates cannot be determined. The lack of such information is likely to lead to unnecessary expansion of the contact investigation.
All Contacts. All contacts should be interviewed for symptoms of TB disease using a standard symptom questionnaire. Symptomatic contacts should receive a chest radiograph and a complete medical evaluation by a physician, regardless of TST or QFT-G status; they also should be isolated appropriately (i.e., inmates should be placed in an AII room if infectious TB is suspected by chest radiograph or clinical findings; staff should not be permitted to work). HIV testing should be considered for all contacts whose HIV status is unknown.
Inmates with Documented Previous Positive TST or QFT-G Results. Inmates who are asymptomatic, HIV-negative, and have previous positive TST or QFT-G results need no further follow-up, other than consideration for "routine" treatment of LTBI, if not completed in the past. However, if such an inmate has any signs or symptoms suggestive of TB, further evaluation should be conducted (e.g., a chest radiograph for persons with respiratory symptoms).
HIV-Infected Inmates. HIV-infected contacts should be interviewed for symptoms, have a TST or QFT-G and chest radiograph performed, and initiate a complete course of treatment for LTBI (once TB disease has been ruled out), regardless of the TST or QFT-G result. Treatment should be initiated even for persons with a history of previous treatment for LTBI or TB disease because of the possibility of re-infection. Those with a history of a negative TST or QFT-G should have a TST or QFT-G placed at baseline and again in 8-10 weeks. The results of the TST or QFT-G will not affect treatment decisions, but they will provide important information for the contact investigation. Anergy testing is not recommended.
Previous TST-Negative or QFT-G-Negative Inmates (HIV Negative). Mandatory tuberculin skin or QFT-G testing of all previously TST- or QFT-G-negative inmate contacts should be conducted at baseline (unless previously tested within 1-3 months of exposure). Testing should be repeated 8-10 weeks from the most recent contact with the source patient.[58,167]
TST and QFT-G Converters. Persons whose TSTs or QFT-Gs convert or those with newly documented, positive TST or QFT-G results should be offered treatment for LTBI unless medically contraindicated. If inmate contacts refuse medically indicated treatment for LTBI, they should be monitored regularly for symptoms. Certain facilities have chosen to monitor HIV-infected contacts with follow-up chest radiographs.
The following steps are involved in conducting a contact investigation and might overlap in time. As soon as a person is confirmed or suspected of having TB disease, the case should be reported to the appropriate local health authorities and contacts promptly evaluated.
Notify correctional management officials. Identification of TB in an inmate or facility staff member can be alarming for other inmates, corrections staff, and the community. The administrator should be notified through appropriate chain of command that a case of TB has been identified in the institution so that appropriate briefing and educational efforts can be initiated.
Conduct a source patient chart review. The following data (with specific dates) should be collected: 1) history of previous exposure to TB, 2) history of TB symptoms (e.g., cough, fever, and night sweats), 3) weight history (particularly unexplained weight loss), 4) chest radiograph reports, 5) previous TST or QFT-G results, 6) mycobacteriology results (e.g., AFB smears, cultures, and susceptibilities), 7) NAA test results, 8) HIV status, and 9) other medical risk factors.
Interview the source patient. A chart review and case interview should be accomplished within 1 working day for persons with AFB smear-positive respiratory specimens or cavitation on chest radiograph and within 3 days for all other persons. Source patients should be asked concerning TB symptom history, with a particular focus on duration of cough. Source patients also should be asked about where they conduct their daily activities. Persons with confirmed or suspected TB who were detained during the course of the infectious period should be interviewed regarding potential community contacts, particularly HIV-infected persons and young children; information regarding the location of community contacts also should be obtained. Source patients should be questioned regarding contacts during a second interview conducted 7-14 days after the first.
Define the infectious period. Defining the infectious period for a source patient helps investigators determine how far back to go when investigating potential contacts. The infectious period is typically defined as 12 weeks before TB diagnosis or onset of cough (whichever is longer). If a patient has no TB symptoms, is AFB smear negative, and has a noncavitary chest radiograph, the presumed infectious period can be reduced to 4 weeks before the date of first positive finding consistent with TB. If the contact investigation reveals that TB transmission occurred throughout the identified infectious period, the period for contact investigation might need to be expanded beyond 12 weeks.
Convene the contact investigation team. After TB is diagnosed, a team of professionals (e.g., infection-control, medical, nursing, custody, and local public health personnel) should be convened and charged with planning the contact investigation. A team leader should be identified and the roles and responsibilities of each team member defined, and a schedule of regular meetings (documented formally with written minutes) should be established. In addition, a communications plan and a plan for handling contact investigation data should be developed.
Update correctional management officials. Administrative personnel should be kept apprised of the strategy, process, and action steps involved in conducting the contact investigation.
Obtain source case inmate traffic history. The dates and locations of the source patient's housing during the infectious period and information regarding employment and education should be obtained. Groups of contacts should be prioritized according to duration of exposure and immune status.
Tour exposure sites. A tour should be conducted of each place the source patient lived, worked, or went to school during the infectious period. In addition, information should be obtained regarding any correctional facility that has housed the source patient during the infectious period, including 1) the number of inmates who are housed together at one time, 2) the housing arrangement (e.g., cells versus dorms), 3) the general size of the air space, 4) the basics of the ventilation system (e.g., whether air is recirculated), 5) the pattern of daily inmate movement (e.g., when eating, working, and recreating), and 6) the availability of data on other inmates housed at the same time as the source patient. The assistance of a facility engineer often is necessary to help characterize the ventilation system and airflow direction within a correctional facility.
Prioritize contacts. Contacts should be grouped according to duration and intensity of exposure. Persons with the most exposure and HIV-infected or other immunosuppressed contacts (regardless of duration of exposure) are considered highest priority. Because progression from exposure to death can be rapid among HIV-infected persons in a facility in which HIV-infected persons are housed or congregated separately, the entire group should be given high priority.
Develop contact lists. Rosters of inmate and employee contacts from each location should be obtained and their current location investigated. Lists of exposed contacts should be generated and grouped according to current location (e.g., still incarcerated, released, and transferred).
Conduct a medical record review on each high-priority contact. TST or QFT-G status, chest radiograph history, history of treatment for LTBI, HIV status, and other high-risk medical conditions should be recorded. Particular attention should be given to weight history and previous visits to facility health-care professionals for respiratory symptoms. Dates should be carefully recorded.
Evaluate HIV-infected contacts for TB disease and LTBI promptly. LTBI therapy should be initiated promptly among these persons once TB disease has been excluded.
Place and read initial TSTs or perform QFT-Gs on eligible contacts. Tuberculin skin or QFT-G testing of all previously TST- or QFT-G-negative inmate contacts should be conducted at baseline (unless previously tested within 1-3 months of exposure). Referrals should be made for persons who have been released or transferred before receiving their initial TST or QFT-G.
Make referrals for contact evaluation. Referrals should be made to the local health department for inmate contacts of the source case who have been released or transferred to another facility. Additionally, family members or frequent visitors of the source patient should be investigated by the health department; follow-up TST or QFT-G results for a substantial percentage of contacts of released inmates have been obtained on re-arrest by matching the list of exposed contacts with the jail intake TST or QFT-G registry.
Calculate the infection rate and determine the need to expand the investigation. To calculate the infection rate, the total number of inmates whose TST or QFT-G has converted from negative to positive should be divided by the total number with a TST placed and read or QFT-G performed. Persons with a history of a prior positive TST or QFT-G should be excluded. The infection rate should be calculated by exposure site. In addition, if using tuberculin skin testing, separately calculating the rate for U.S.- versus foreign-born inmates might provide useful data; foreign-born contacts often have a history of BCG vaccination, and a TST "conversion" among these contacts might represent a vaccination-associated "booster" TST response. The contact investigation team should analyze the infection rate(s) and decide whether to expand the investigation.
Place and read follow-up TSTs or perform follow-up QFT-Gs. Follow-up TSTs or QFT-Gs for contacts who had a negative TST or QFT-G result on initial testing should be placed 8-10 weeks after exposure to the source patient has ended. Referrals should be made for persons who have been released or transferred and need a follow-up TST or QFT-G.
Determine the infection/transmission rate. The infection rate from the second round of testing should be calculated. In addition, the need to expand the investigation should be determined.
Write a summary report. The summary report should briefly describe the circumstances of the investigation, how it was conducted, the results of the investigation (e.g., the number of secondary cases identified and the infection and transmission rates), and any special interventions required (including follow-up plans). The report should be distributed to corrections administrators and the local health department.
Asymptomatic contacts with normal chest radiographs typically do not require isolation.
Morbidity and Mortality Weekly Report. 2006;55(27):1-44. © 2006 Centers for Disease Control and Prevention (CDC)
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Cite this: Prevention and Control of Tuberculosis in Correctional and Detention Facilities: Recommendations from CDC - Medscape - Jul 07, 2006.