Reported Tuberculosis in the United States, 2020

Print
Related Pages

Return to Main Menu

Appendix B

(Revised September 23, 2021)  

Recommendations for Counting Reported Tuberculosis Cases were first published in July 1997. Since that time, substantial changes have occurred, and questions have been raised within the field of tuberculosis (TB) surveillance. This document is reviewed annually, and minor modifications and clarifications are incorporated. 

A distinction should be made between reporting TB cases to a health department and counting TB cases for determining disease incidence. Throughout each year, TB cases and persons being evaluated for TB are reported to public health authorities by such sources as clinics, hospitals, laboratories, and health care providers. From these reports, the state or local TB control officer must determine which cases meet the surveillance definition for TB disease and whether the case is countable. These countable TB cases are then reported to the Centers for Disease Control and Prevention (CDC). 

Beginning in 2009, state and local TB control officers also report to CDC those TB cases that are verified but not countable for morbidity statistics, as a measure of programmatic and case management burden. Noncountable cases include persons with TB disease recurring within a consecutive 12-month period after the patient completed TB therapy. 

I. Reporting TB Cases

CDC recommends that health care providers and laboratories be required to report all TB cases or persons being evaluated for TB to state and local health departments based on “Tuberculosis Case Definition for Public Health Surveillance” (Appendix A). This notification is essential for TB programs to 

  • ensure case supervision, 
  • ensure completion of recommended therapy, 
  • ensure completion of contact investigations, 
  • evaluate program effectiveness, and 
  • assess trends and characteristics of TB morbidity. 

II. TB Surveillance

For purposes of surveillance, a case of TB is defined based on laboratory or clinical evidence of active disease caused by M. tuberculosis complex* 

*Because many laboratories use tests that do not routinely distinguish Mycobacterium tuberculosis from closely related species, these laboratories report culture results as being positive or negative for “Mycobacterium tuberculosis complex.” Although in approximately all cases of human disease, isolates in the M. tuberculosis  complex are, in fact, M. tuberculosis, other species are possible. Other species in the M. tuberculosis  complex include Mycobacterium bovis, Mycobacterium africanum, Mycobacterium microti, Mycobacterium canettii, Mycobacterium caprae, Mycobacterium pinnipedii, and Mycobacterium mungi. The inclusion of these species in M. tuberculosis complex should not affect public health laboratories or programs, because only a few laboratories identify to the species level. These 7 species are approximately identical in DNA homology studies. In terms of their ability to cause clinical disease or be transmissible from person to person, M. bovis, M. africanum, M. microti, M. canettii, M. caprae, M. pinnipedii, and M. mungi  behave like M. tuberculosis; therefore, disease caused by any of the organisms should be reported as TB, using the Report of Verified Case of TB (RVCT). The only exception is the bacillus Calmette-Guérin (BCG) strain of M. bovis, which can be isolated from persons who have received the vaccine for protection against TB or as cancer immunotherapy; disease caused by the BCG strain of M. bovis should not  be reported as TB. 

  1. Laboratory Case Definition

isolation of M. tuberculosis complex from a clinical specimen. Use of rapid identification techniques for M. tuberculosis  performed on a culture from a clinical specimen (e.g., DNA probes or high-pressure liquid chromatography) is acceptable under this criterion. 

or 

demonstration of M. tuberculosis  from a clinical specimen by nucleic acid amplification test. Nucleic acid amplification tests (NAAT) must be accompanied by cultures of mycobacterial species. However, for surveillance purposes, CDC will accept results obtained from NAAT approved by the Food and Drug Administration (FDA) and used according to the approved product labeling on the package insert, or a test produced and validated in accordance with applicable FDA and Clinical Laboratory Improvement Amendments regulations. 

or 

demonstration of acid-fast bacilli (AFB) in a clinical specimen when a culture has not been or cannot be obtained or is falsely negative or contaminated. Historically, this criterion has been most commonly used in diagnosing TB in the postmortem setting. 

  1. Clinical Case Definition

In the absence of laboratory confirmation of M. tuberculosis  complex after a diagnostic process has been completed, persons must have all  of the following criteria for a clinical TB diagnosis: 

  • evidence of TB infection based on a positive tuberculin skin test result or positive interferon-gamma release assay for tuberculosis, and current treatment with ≥2 anti-TB medications; 

and 

1 of the following: 

  • signs and symptoms compatible with current TB disease (e.g., an abnormal chest radiograph or abnormal chest computerized tomography scan or other chest imaging study; 

or 

  • clinical evidence of current disease (e.g., fever, night sweats, cough, weight loss, hemoptysis). 

NOTE: The software for TB surveillance developed by CDC includes a calculated variable called “VERCRIT,” for which one of the values is Provider Diagnosis. Provider Diagnosis is selected when the user chooses to override a Suspect (i.e., presumptive TB case or person being evaluated for TB disease) default value in the case verification screen as Verified by Provider Diagnosis. Thus, Provider Diagnosis is not a component of the case definition for TB in the “TB Case Definition for Public Health Surveillance” (Appendix A). CDC’s national morbidity reports have traditionally included all TB cases that are considered verified by the reporting areas, without a requirement that cases meet the published case definition. 

III. Counting TB Cases

Cases that meet the CDC surveillance case definition for verified TB are counted by 52 reporting areas with count authority (50 U.S. states, the District of Columbia, and New York City) to determine annual incidence for the United States. The remaining eight reporting areas (American Samoa, Federated States of Micronesia, Guam, Republic of the Marshall Islands, Commonwealth of the Northern Mariana Islands, Puerto Rico, Republic of Palau, and the U.S. Virgin Islands) report cases to CDC but are not included in the annual incidence for the United States. The laboratory and clinical case definitions are the two diagnostic categories used in the CDC “Tuberculosis Case Definition for Public Health Surveillance” (Appendix A). 

The majority of verified TB cases are accepted for counting on the basis of laboratory confirmation of M. tuberculosis  complex from a clinical specimen. 

A person might have >1 discrete (separate and distinct) episode of TB. If disease recurs within  any twelve-month consecutive period after the patient completed therapy, count only 1 episode as a case. However, if TB disease recurs in a person, and  if >12 months have elapsed since the person completed TB therapy or since the person was lost to supervision, the TB case is considered a separate episode and should be counted as a new case. 

Mycobacterial diseases other than those caused by M. tuberculosis complex should not be counted in TB morbidity statistics unless concurrent TB occurs.

A. Verified TB Cases

CASES THAT SHOULD BE COUNTED 

Only verified TB cases that meet the laboratory or clinical case definitions should be counted (see Section II). TB diagnosis must be verified by the TB control officer or designee. The CDC surveillance case definition for TB (Appendix A) describes and defines the criteria to be used in the case definition for TB disease. 

CASES THAT SHOULD NOT BE COUNTED 

If diagnostic procedures have not been completed, TB should be confirmed before the case is counted. A case of illness should not be counted in a patient for whom ≥2 anti-TB medications have been prescribed for preventive therapy for exposure to multidrug-resistant TB or while the diagnosis is still pending. 

B. Nontuberculous Mycobacterial Disease

CASES THAT SHOULD BE COUNTED 

An episode of TB disease diagnosed concurrently with another nontuberculous mycobacterial disease (NTM) should be counted as a TB case. 

CASES THAT SHOULD NOT BE COUNTED 

Disease attributed to or caused by NTM alone should not be counted as a TB case. 

C. TB Cases Reported at Death

CASES THAT SHOULD BE COUNTED 

TB cases first reported to the health department at the time of a person’s death are counted as incident cases, provided the person had current disease at the time of death. The TB control officer should verify the TB diagnosis. 

CASES THAT SHOULD NOT  BE COUNTED 

A case of TB should not be counted if no evidence exists of current disease at the time of death or at autopsy. 

D. Immigrants, Refugees, Permanent Resident Aliens, Foreign Visitors, and Border Crossers†

CASES THAT SHOULD BE COUNTED 

Persons who are examined after arriving in the United States and are diagnosed with clinically active TB disease requiring TB treatment should be counted by the locality where the diagnostic evaluation for TB began, regardless of citizenship or residency status. 

In addition, border crossers† who receive TB treatment from a U.S. locality for a total of ≥90 consecutive days (excluding weekends) should be counted by the locality where they receive treatment. 

Foreign visitors (e.g., students, commercial representatives, and diplomatic personnel) who receive a diagnosis of TB, are receiving TB treatment, and have been in the United States for ≥90 days should be counted by the locality of current residence. 

CASES THAT SHOULD NOT  BE COUNTED 

Any person who received a TB diagnosis and who started TB treatment in another country should not be counted as a new case but should be reported as a person with a verified noncountable TB case. 

Border crossers and other foreign visitors who are in the United States for <90 days total and begin TB treatment in the United States but return to their native country to continue therapy should not be reported or counted by the U.S. locality where they receive treatment. 

†Border crosser is defined by U.S. Citizenship and Immigration Services1 as “an alien resident of the United States reentering the country after an absence of less than six months in Canada or Mexico, or a nonresident alien entering the United States across the Canadian border for stays of no more than six months, or across the Mexican border for stays of no more than 72 hours.” Border crossers might go back and forth across the border frequently during a short period. 

E. Out-of-State or Out-of-Area Residents

CASES THAT SHOULD BE COUNTED 

A person’s TB case should be counted by the locality in which he or she resides at the time of diagnosis. TB in a person who has no address should be counted by the locality where TB is diagnosed and treated. The TB control officer should notify the out-of-state or out-of-area TB control officer of the person’s home locality to (1) determine whether the case has been counted already to avoid double counting, and (2) agree on which TB control office should count the case if it has not yet been counted. 

CASES THAT SHOULD NOT BE COUNTED 

A case in a patient with newly diagnosed TB who is an out-of-area resident and whose TB has already been counted by the out-of-area TB control office should not be counted. 

F. Migrants and Other Persons with Transient Living Arrangements

CASES THAT SHOULD BE COUNTED 

Persons without any fixed U.S. residence are considered to be the public health responsibility of their present locality, and their TB case should be counted by the locality where the diagnostic evaluation that led to the TB diagnosis was initiated. 

CASES THAT SHOULD NOT  BE COUNTED 

Cases among transient TB patients should not be counted when evidence exists that they have already been counted by another locality (e.g., because they began treatment before arriving in the present locality). 

G. Cases Occurring in Federal Facilities (e.g., Military and Veterans Administration Facilities)

CASES THAT SHOULD BE COUNTED 

Cases among military personnel, their dependents, or veterans should be reported and counted by the locality where the persons are residing in the United States at the time of diagnosis and initiation of treatment. However, if military personnel or dependents are discovered to have TB at a military base outside the United States but are referred elsewhere for treatment (e.g., a military base located within the United States), the TB case should be reported and counted where treatment is administered and not where the diagnosis was made. 

CASES THAT SHOULD NOT BE COUNTED 

A case that was already counted by another locality in the United States should not be counted. 

H. Cases Associated with the Indian Health Service

CASES THAT SHOULD BE COUNTED 

TB should be reported to the local health authority (e.g., state or county) and counted where diagnosed and treatment is initiated. However, for specific groups (e.g., the Navajo Nation) located across multiple states, health departments should discuss each case and determine which locality should count the case. 

CASES THAT SHOULD NOT BE COUNTED 

A case should not be counted if the case was already counted by another locality. 

I. Cases Occurring in Correctional Facilities (e.g., Local, State, Federal, and Military)

CASES THAT SHOULD BE COUNTED 

Frequently, persons who reside in local, state, federal, or military correctional facilities are transferred or relocated within or between different correctional facilities. TB among these persons should be reported to the local health authority and counted by the locality where the diagnostic evaluation that led to the TB diagnosis was initiated. 

CASES THAT SHOULD NOT BE COUNTED 

Correctional facility residents’ TB cases that were counted elsewhere by another locality or correctional facility, even if treatment continues at another locale or correctional facility, should not be counted. 

J. Peace Corps, Missionaries, and Other Citizens Residing Outside the United States

CASES THAT SHOULD NOT BE COUNTED 

TB among persons who received their diagnosis outside the United States should not be counted. TB among these persons should be counted by the country in which they are residing, regardless of their plans to return to the United States for further evaluation or treatment. 

IV. Recommended Administrative Practices

To promote uniformity in TB case counting, the following administrative procedures are recommended: 

  1. All TB cases verified by the 52 reporting areas with count authority (50 U.S. states, DC, and New York City) during the calendar year (by December 31) will be included in the annual U.S. incidence count for that year. All TB cases verified during the calendar year by a reporting area with count authority from 1 of the remaining eight reporting areas (American Samoa, Federated States of Micronesia, Guam, Republic of the Marshall Islands, Commonwealth of the Northern Mariana Islands, Puerto Rico, Republic of Palau, and the U.S. Virgin Islands) are also counted but are not included in the annual incidence for the United States. Cases for which bacteriologic results are pending or for which confirmation of disease is questionable for any other reason should not be counted until their status is clearly determined; they should be counted at the time they meet the criteria for counting. This means that a case reported in 1 calendar year might be included in the morbidity count for the following year. All reporting areas should ensure that agreement exists between final local and state TB figures reported to CDC. Reporting areas might not use this recommended protocol. They may wait until the beginning of the following year when they have received and processed all of the TB cases for inclusion in the annual case count for the previous year. If reporting areas decide to revise their protocols, they should be aware that their TB trends might change.
  2. Occasionally, TB is reported to health departments by telephone, by letter or fax, or on forms other than the RVCT. Such information should be accepted as an official morbidity report if sufficient details are provided; otherwise, the notification should be used as an indicator of a possible TB case that should be investigated promptly for confirmation. 

V. Glossary of TB Surveillance Terms

case: an episode of TB disease in a person meeting the laboratory or clinical criteria for TB, as defined in “Tuberculosis Case Definition for Public Health Surveillance” (see Section II for criteria). 

counting of a TB case: the process whereby a reporting area with count authority evaluates verified TB cases against count criteria (e.g., assesses for case duplication). These cases are then counted for morbidity in that locality (e.g., state or county) and reported to CDC for national morbidity counting. Noncountable, verified cases should also be sent to CDC. 

Mycobacterium tuberculosis complex: a genetically related group of Mycobacterium  species that can cause TB in humans or other animals. Because the majority of laboratories use tests that do not routinely distinguish M. tuberculosis from closely related species, those laboratories report culture results as being positive or negative for M. tuberculosis  complex. Although in approximately all cases of human disease, isolates in the M. tuberculosis complex are, in fact, M. tuberculosis, other species are possible. For example, a study in San Diego reported that 6% of human TB was caused by Mycobacterium bovis; cultures from these cases would be reported by the majority of laboratories as being positive for M. tuberculosis complex.2 Other species in the M. tuberculosis complex include Mycobacterium africanum, Mycobacterium microti, Mycobacterium canettii, Mycobacterium caprae, and Mycobacterium pinnipedii. Although M. microti, M. canettii, M. caprae, and M. pinnipedii are newly described species, their inclusion in M. tuberculosis complex should not affect public health laboratories or programs because only a few laboratories identify the species level. These 7 species are almost identical in DNA homology studies. In terms of their ability to cause clinical disease or be transmissible from person to person, M. bovis, M. africanum, M. microti, M. canettii, M. caprae, and M. pinnipedii  behave similar to M. tuberculosis; therefore, disease caused by any of the organisms should be reported as TB by using the RVCT form. The only exception is the bacillus Calmette-Guérin (BCG) strain of M. bovis, which might be isolated from persons who have received the vaccine for protection against TB or as cancer immunotherapy; disease caused by the BCG strain of M. bovis should not be reported as TB. 

nontuberculous mycobacteria: mycobacteria other than M. tuberculosis  complex that can cause human infection or disease. Common nontuberculous mycobacteria (NTM) include Mycobacterium avium  complex (also known as “MAC”) (Mycobacterium avium or Mycobacterium intracellulare), Mycobacterium kansasii, Mycobacterium marinum, Mycobacterium scrofulaceum, Mycobacterium chelonae, Mycobacterium fortuitum, and Mycobacterium simiae. Other terms have been used to represent NTM, including “MOTT” (mycobacteria other than TB) and “atypical” mycobacteria.

reporting area: areas responsible for counting and reporting verified TB cases to CDC. A total of 60 areas report cases to CDC: the 50 U.S. states, the District of Columbia (D.C.), New York City, American Samoa, Federated States of Micronesia, Guam, Republic of the Marshall Islands, Commonwealth of the Northern Mariana Islands, Puerto Rico, Republic of Palau, and the U.S. Virgin Islands. The annual incidence of TB for the United States is based on 52 of these reporting areas (the 50 U.S. states, D.C., and New York City). 

suspected TB case: a case for which a high index of suspicion exists for active TB (e.g., a person with signs or symptoms consistent with TB) and that is currently under evaluation.  However, “possible TB case,” “presumptive TB case” or “person being evaluated for TB” is preferred. 

verification of a TB case: the process whereby a TB case, after the diagnostic evaluation is complete, is reviewed at the local level (e.g., state or county) by a TB control official who is familiar with TB surveillance definitions; if all the criteria for a TB case are met, the TB case is then verified and eligible for counting. 

References