Skip directly to site content Skip directly to page options Skip directly to A-Z link


Centers for Disease Control and Prevention. CDC twenty four seven. Saving Lives, Protecting People
														Search

		Submit


Tuberculosis (TB)


Facebook
        Twitter
        LinkedIn
        Syndicate





Reported Tuberculosis in the United States, 2017										Related Pages
										Return to Main Menu
**Estimates of Recent Transmission, 2016–2017**
Overview
Control of recent TB transmission is an important component of the national TB elimination strategy. Programs can begin to monitor trends in recent transmission by comparing current (2016–2017) state- and county-specific estimates published in this section of the annual report with 2015–2016 estimates published in the previous edi­tion of the annual report.
These estimates may also help state and local TB programs to:
use limited public health resources to plan and prioritize TB control activities,
enhance service delivery by applying sufficient resources,
identify geographic, demographic, and social disparities in the proportion of cases attributed to recent transmission,
develop specific prevention strategies and interventions to interrupt transmission, and
facilitate connections among jurisdictions to share TB control strategies.Recent transmission can occur in communities regardless of the overall TB incidence in a particular state; even states with a low incidence of TB overall may have counties where extensive recent transmission is occurring.1 However, these estimates are not intended for comparisons across jurisdictions because TB incidence, demographics, and molecular epidemiology vary considerably among states and counties.
Terminology
*Recent transmission*
A TB case is designated as attributed to recent transmission if a plausible source case2 can be identified in a person who:
has the same *M. tuberculosis*genotype,
has an infectious form of TB disease,
resides within 10 miles of the TB case,
is 10 years of age or older, and
was diagnosed within 2 years before the TB case.Recent transmission estimates are mapped as counts to describe the relative numbers of cases attributed to recent TB transmission (Figure 1)image icon.
*Extensive recent transmission*
A TB case is designated as attributed to extensive recent transmission when the criteria above for recent transmission are met, and furthermore the case belongs to a plausible transmission chain of 6 or more cases (i.e., the plausible source case and 4 or more other cases identified within 3 years before the TB case). Extensive recent transmission estimates are presented as a percentage of all genotyped cases to identify areas and populations disproportionately affected by extensive recent transmission among counties with 10 or more genotyped cases (Figure 2)image icon.
Recent Transmission in the United States
Nationally, 1,787 (13.1%) of 13,650 genotyped cases reported during 2016-2017 are attributed to recent transmission (Table 57). Among all genotyped cases, 4.6% (n=625) are attributed to extensive recent transmission.
*Geography*
Forty-seven counties (or county equivalents) had >5% of cases attributed to extensive recent transmission (Table 58). In these counties, the median number of genotyped cases was 38 (range: 10–904 cases). The median percentage of genotyped cases occurring in U.S.-born patients (48.0%) was significantly higher in these 47 counties compared with the national proportion of TB cases among U.S.-born persons (29.7%).
*Demographic and social characteristics*
Cases among U.S.-born persons were more frequently attributed to both recent transmission (25.6%) and extensive recent transmission (10.6%) than cases among non-U.S.–born persons (7.8% and 2.0%, respectively) (Table 59). Racial disparities in the proportions of cases attributed to recent transmission and extensive recent transmis­sion were identified among American Indians/Alaska Natives, Native Hawaiian/Other Pacific Islander, and non-Hispanic Blacks/African Americans (Table 59). In addition, greater proportions of cases attributed to recent transmission and extensive recent transmission were identified among persons who reported drug use and excess alcohol use compared with persons without these risk factors. Cases were more also frequently attributed to recent transmission and extensive recent transmission among people experiencing homelessness within the past year and residents of a correctional facil­ity at the time of diagnosis.
Limitations
These methods for estimating recent transmission can only be applied to culture-confirmed, genotyped cases (n=13,650 cases reported in 2016 and 2017). Pediatric and other clinically diagnosed cases are likely underrepresented because cases without genotyping results are excluded. This limitation is especially relevant for TB cases in young children, which are most likely to be due to recent transmission.
The proportions of cases attributed to recent transmission are generally higher in areas with fewer *M. tuberculosis* genotypes and where prevalent or common genotypes (Table 26) have been predominant for many years; in relatively closed populations and remote areas (e.g., parts of Alaska) recent transmission may be overestimated. As evidenced by whole-genome sequencing (WGS), genomic diversity may be greater than what is apparent using current genotyping methods among cases reported by areas bordering Mexico. Consequently, definitively distinguishing cases attributed to recent transmission from cases caused by reactivation of longstanding, untreated latent TB infection by using the methods in this report can be difficult.
Future Applications
Although national surveillance data can only provide aggregated estimates, these methods offer state and local TB control programs new opportunities to track trends in recent transmission and prioritize public health activities and interventions. In 2018, CDC established the National TB Molecular Surveillance Center to perform WGS on at least one isolate from every culture-positive TB case in the United States. As universal WGS results are further adopted into program practice, characterization and investigation of recent TB transmission will become increasingly precise.
ReferencesYuen CM, Kammerer JS, Marks K, Navin TR, France AM. Recent Transmission of Tuberculosis – United States, 2011-2014external icon.*PLoS One* 2016; 11: e0153728.125
France AM, Grant J, Kammerer JS, Navin TR. A field-validated approach using surveillance and genotyping data to estimate tuberculosis attributable to recent transmission in the United States. *Am J Epidemiol* 2015; 182: 799-807.
							
					
						Page last reviewed:  November 6, 2018					Content source: 	Division of Tuberculosis Elimination, National Center for HIV, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention homeTuberculosisBasic TB Factsplus iconHow TB SpreadsLatent TB Infection and TB DiseaseSigns & SymptomsTB Risk FactorsExposure to TBTB PreventionVaccinesTB & HIV CoinfectionTB and DiabetesTB TermsPersonal StoriesTesting & Diagnosisplus iconWho Should be TestedTesting for TB InfectionTesting in BCG-Vaccinated PersonsTB Screening and Testing of Health Care PersonnelTesting During PregnancyDiagnosing latent TB infection and TB diseaseTreatmentplus iconDeciding When to Treat Latent TB InfectionTreatment Regimens for Latent TB Infection (LTBI)Treatment for TB DiseaseAdverse EventsTB Treatment of Persons Living with HIVTB Treatment and PregnancyTB Treatment for ChildrenFrequently Asked QuestionsDrug-Resistant TBResearchplus iconTB Epidemiologic Studies Consortiumplus iconResearch ProjectsPublicationsTB Trials Consortiumplus iconStudy DescriptionsBackgroundBehavioral & Social Science ResearchHealth Care Settingsplus iconTB Infection Control in Health Care SettingsResources for TB Screening and Testing of Health Care Personnelplus iconFrequently Asked QuestionsTB in Specific Populationsplus iconHealth DisparitiesAsian PersonsBlack or African American PersonsHispanic or Latino PersonsChildrenPregnancyCorrectional FacilitiesPeople Experiencing HomelessnessInternational TravelersLaboratory Informationplus iconDrug Susceptibility TestingFalse-Positive Investigation ToolkitInterim Laboratory Biosafety Guidance for XDR  tuberculosis strainsModel Performance Evaluation Program (MPEP)Rapid Molecular Testing to Detect Drug-Resistant TB in the USplus iconExecutive SummaryIntroductionBackground on Tests for Molecular Detection of DRGeneral Considerations and Principles for a Molecular DR Testing ServicePossible Scenarios and Scope of Testing for a Molecular DR Testing ServiceResearch NeedsGeneral Recommendations of the Expert PanelCommunication Plan for the ReportRecommendationsReferencesPanel Members and CDC ParticipantsAppendix 1Appendix 2Appendix 3The Uses of Nucleic Acid Amplification Tests for the Diagnosis of TBplus iconGeneral ConsiderationsGeneral Recommendations of the Expert PanelRecommendations to ACET, CDC, DTBEData & Statisticsplus iconTB Incidence in the United StatesReported TB in the US, 2022 Surveillance Reportplus iconNational DataReporting Area DataRisk FactorsDemographicsTB Treatment and Case OutcomesDrug-Resistant TBMolecular SurveillanceTuberculosis in the United States, 2022 (Slide Set)Archived Surveillance Reports and Slide Sets2021 State and City ReportArchived State and City ReportsProfessional Resources & Toolsplus iconTools for Healthcare ProvidersResources for TB Programsplus iconStrengthening Civil Surgeons’ Capacity to Improve LTBI Surveillance and Outcomes Among Status AdjustersNotice of Funding Opportunity (NOFO)Program EvaluationTB Centers of ExcellenceTB Elimination AllianceTB Genotypingplus iconConventional TB GenotypingWhole Genome SequencingTB GIMSAnalytic ToolsLatent Tuberculosis Infection ResourcesPublications & Productsplus iconPatient and Public MaterialsFact SheetsGuidelinesplus iconControl & EliminationDrug-Resistant TBInfection Control & PreventionLaboratory & GenotypingTB & HIVTB in Specific PopulationsTesting & DiagnosisTreatmentVaccines & ImmunizationsArchived TB GuidelinesGuides & Toolkitsplus iconAggregate ReportsCDC TB Surveillance TrainingCore CurriculumEffective TB Interviewing for Contact InvestigationEthnographic GuidesFalse-Positive Investigation ToolkitForging Partnerships to Eliminate TuberculosisGuide to Application of GenotypingLTBI: A Guide for Primary Health Care ProvidersMantoux Tuberculin Skin Testing ProductsReport of Verified Case of Tuberculosis (RVCT)Self-Study ModulesTB Contact Investigation Interviewing Skills CourseTB eDOT ToolkitUnderstanding the TB Cohort Review ProcessNewslettersplus iconTB Notes, No. 4, 2023TB Notes, No. 3, 2023TB Notes. No. 2, 2023TB Notes. No. 1, 2023TB Notes, No. 4, 2022TB Notes, No. 3, 2022TB Notes, No. 2, 2022TB Notes, No. 1, 2022TB Notes, No. 4, 2021TB Notes, No. 3, 2021TB Notes, No. 2, 2021TB Notes, No. 1, 2021Pamphlets, Brochures, Bookletsplus iconQuestions and AnswersPatient Education SeriesTuberculosis - Get the FactsTuberculosis - The Connection between TB and HIV12-Dose Regimen for Latent TB Infection-Patient Education BrochurePostersplus iconMantoux Tuberculin Skin Test Wall ChartWorld TB DayThink TBStop TBTake on TBReports & Articlesplus iconDTBE Authored Journal ArticlesTuberculosis Laboratory Aggregate ReportsSlide Setsplus iconIntroduction to TuberculosisEpidemiology of Tuberculosis Among Non-U.S.​–Born Persons in the United States, 1993–2016Self-Study Modules on Tuberculosis, 1-5 Slide SetsThe Tuberculosis (TB) in Correctional Settingsplus iconFacilitator GuideIntroduction to TB GenotypingEpidemiology of Tuberculosis in Correctional Facilities, United States, 1993-2017Prevention and Control of Tuberculosis in Correctional and Detention FacilitiesGuidelines for Preventing the Transmission of M. TB in Health care SettingsInvestigation of Contacts of Persons with Infectious TBEpidemiology of Pediatric Tuberculosis in the United StatesTargeted Tuberculosis Testing and Treatment of Latent Tuberculosis InfectionElectronic Tools & ResourcesWeb-Based Courses & Webinarsplus iconTB 101 for Health Care WorkersContent SyndicationInfographicsplus iconSocial Media GraphicsCustomizable Take on TB Infographic with InstructionsEventsWorld TB Dayplus iconU.S. TB ChampionsHistoryFeaturesplus iconTB Risk FactorsTreating Latent TB Infection with Short-Course RegimensWorld Tuberculosis (TB) Day 2021World Tuberculosis (TB) Day 2020Linksplus iconState TB Control OfficesAbout Usplus iconMission Statement and Activitiesplus iconDTBE Strategic PlanNational TB Program ObjectivesOrganization ChartAdvisory Groupsplus iconFederal TB Task Force To receive email updates about this page, enter your email address: Email Address			What's this?				Submit


About CDC
					Contact Us
					800-232-4636
 Facebook Twitter Instagram LinkedIn Youtube Pinterest Snapchat
 CONTACT CDC
				Contact Us
							Call 800-232-4636
							Email Us
			ABOUT CDC
				About CDC
							Jobs
							Funding
			POLICIES
				Accessibility
							External Links
							Privacy
							Policies
							No Fear Act
							FOIA
							OIG
							Nondiscrimination
							Vulnerability Disclosure Policy
			CONNECT WITH US
				Facebook
								Twitter
								Instagram
								LinkedIn
							Youtube
								Pinterest
								Snapchat
								Email
			LANGUAGES
				Español
							繁體中文
							Tiếng Việt
							한국어
							Tagalog
							Русский
							العربية
							Kreyòl Ayisyen
							Français
							Polski
							Português
							Italiano
							Deutsch
							日本語
							فارسی
							English


U.S. Department of Health & Human Services
			Accessibility
			External Links
			Privacy
			Policies
			No Fear Act
			FOIA
			Nondiscrimination
			OIG
			Vulnerability Disclosure Policy
			USA.gov


Exit Notification / Disclaimer Policy Close
 Links with this icon  indicate that you are leaving the CDC website. The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website.
				Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.
				You will be subject to the destination website's privacy policy when you follow the link.
				CDC is not responsible for Section 508 compliance (accessibility) on other federal or private website. Website Disclaimers
 Cancel Continue