Genomic Epidemiology of Treponema pallidum and Circulation of Strains With Diminished tprK Antigen Variation Capability in Seattle, 2021-2022.

BACKGROUND: The incidence of syphilis continues to increase in the United States, yet little is known about Treponema pallidum genomic epidemiology within American metropolitan areas. METHODS: We performed whole-genome sequencing and tprK deep sequencing of 28 T. pallidum-containing specimens, collected mostly from remnant Aptima swab specimens from 24 individuals from Seattle Sexual Health Clinic during 2021-2022. RESULTS: All 12 individuals infected with Nichols-lineage strains were men who have sex with men, while a specific SS14 cluster (mean, 0.33 single-nucleotide variant) included 1 man who has sex with women and 5 women. All T. pallidum strains sequenced were azithromycin resistant via 23S ribosomal RNA A2058G mutation. Identical T. pallidum genomic sequences were found in pharyngeal and rectal swab specimens taken concurrently from the same individuals. The tprK sequences were less variable between patient-matched specimens and between epidemiologically linked clusters. We detected a 528-base pair deletion in the tprK donor site locus, eliminating 9 donor sites, in T. pallidum genomes of 3 individuals with secondary syphilis, associated with diminution of TprK diversity. CONCLUSIONS: We developed an end-to-end workflow for public health genomic surveillance of T. pallidum from remnant Aptima swab specimens. tprK sequencing may assist in linking cases beyond routine T. pallidum genome sequencing. T. pallidum strains with deletions in tprK donor sites currently circulate and are associated with diminished TprK antigenic diversity.

Trends in Chlamydia trachomatis Treatment Prescribing Practices in King County, Washington, 2010-2018.

BACKGROUND: In 2021, national Chlamydia trachomatis (CT) treatment guidelines changed from recommending either azithromycin (1 g; single dose) or doxycycline (100 mg twice daily for 7 days) to recommending only doxycycline as first-line treatment. The distribution and trends in CT prescribing practices before the guidelines change is largely unknown. METHODS: We conducted a trends analysis using Washington STD surveillance data. We included all female cases of urogenital CT 15 years or older who resided in King County and were diagnosed between 2010 and 2018. Surveillance data included information on demographics, sexual history, clinical features, diagnosing facility (eg, emergency department, family planning), and treatment regimen. We conducted descriptive analyses to examine trends in prescribing practices over time and by facility type. We used Poisson regression to examine the association between CT case characteristics and receipt of receipt of azithromycin. RESULTS: There were 36,830 cases of female urogenital CT during the study period. The percent of cases receiving azithromycin increased significantly from 86% in 2010 to 94% in 2018; the percent receiving doxycycline decreased from 13% to 5%. Five of the 8 facility types prescribed azithromycin to >95% of CT cases by 2018. Cases who were younger or cases of color were more likely to receive azithromycin (versus doxycycline) compared with older and White cases, respectively. CONCLUSIONS: A substantial shift in CT prescribing practices will be needed to adhere to new CT treatment guidelines. Our findings highlight the need for targeted provider education and training to encourage the transition to doxycycline use.

Sexually Transmitted Infection Partner Services Outcomes Before and During the SARS-CoV-2 Pandemic in King County, WA.

BACKGROUND: SARS-CoV-2 pandemic mitigation efforts resulted in reallocation of public health personnel, likely impacting provision of timely sexually transmitted infection partner services (PS). We describe PS outcomes before and during the pandemic in King County, WA. METHODS: We examined PS outcomes for syphilis and gonorrhea cases diagnosed in 2019 and 3 periods in 2020 (pre-lockdown: January 1, 2020-March 23, 2020; lockdown: March 24, 2020-June 5, 2020; post-lockdown: June 6, 2020-December 31, 2020). We described changes over time in 3 PS outcomes: cases initiated, interviewed, and with named sex partners. We calculated adjusted prevalence ratios (aPRs) with Poisson regression comparing these outcomes in the 2020 periods with 2019. RESULTS: Reported gonorrhea (4611 vs. 4179) and syphilis (665 vs. 586) cases declined from 2019 to 2020. In 2019, 60.7% of cases were initiated, compared with 42.1% before lockdown (aPR, 0.74; 95% confidence interval [CI], 0.70%-0.78%), 41.7% during lockdown (aPR, 0.79; 95% CI, 0.73-0.85), and 41.7% after lockdown (aPR, 0.81; 95% CI, 0.77-0.85). Among initiated cases, the proportion interviewed also seemed to drop in the 3 lockdown periods (52.4%, 41.0%, 44.1%) compared with 2019 (55.7%). However, in adjusted analyses, the prevalence of interview among case patients was only lower pre-lockdown (aPR, 0.91; 95% CI, 0.85-0.99), and higher during (aPR, 1.10; 95% CI, 1.01-1.20) and after (aPR, 1.12; 95% CI, 1.06-1.19). Interviewed patients named partners more often during (21.4%; aPR, 1.35; 95% CI, 1.05-1.74) and less often after lockdown (16.0%; aPR, 0.63; 95% CI, 0.51-0.79), compared with 2019 (26.6%). CONCLUSIONS: These results underscore the need for a trained public health worker reserve, and plans for deployment of existing workers and prioritization of cases to continue essential sexually transmitted infection public health activities during public health crises.

Asymptomatic and Subclinical Mpox: An Association With Modified Vaccinia Ankara Vaccine.

BACKGROUND: How often mpox causes asymptomatic infections, particularly among persons who have received the Modified Vaccinia Ankara (MVA) vaccine, is unknown. METHODS: We performed mpox polymerase chain reaction testing on rectal and pharyngeal specimens collected from symptomatic and asymptomatic patients at a sexual health clinic in Seattle, WA, between May 2022 and May 2023. Analyses evaluated the prevalence of asymptomatic or subclinical infection and, among persons with polymerase chain reaction-positive tests, the association of MVA vaccination status with the symptomatic infection. RESULTS: The study population included 1663 persons tested for mpox during 2353 clinic visits. Ninety-three percent of study participants were cisgender men and 96% were men who have sex with men. A total of 198 symptomatic patients (30%) had a first mpox-positive test during 664 visits. Eighteen patients (1.1%) tested during 1689 visits had asymptomatic or subclinical mpox based on a positive rectal or pharyngeal test done in the absence of testing done because of clinical suspicion for mpox. Fourteen (78%) of 18 persons with asymptomatic/subclinical mpox and 53 (26%) of 198 persons with symptomatic mpox had received at least 1 dose of the MVA vaccine ( P < 0.0001). Controlling for calendar month, study subjects who received 1 and 2 doses of MVA vaccine were 4.4 (95% confidence interval, 1.3-15) and 11.9 (3.6-40) times more likely to have asymptomatic versus symptomatic mpox, respectively, than persons who were unvaccinated. CONCLUSIONS: Asymptomatic mpox is uncommon. Modified Vaccinia Ankara vaccination is associated with an asymptomatic/subclinical infection among persons with mpox.

Prior Exposure to Azithromycin and Azithromycin Resistance Among Persons Diagnosed With Neisseria gonorrhoeae Infection at a Sexual Health Clinic: 2012-2019.

BACKGROUND: There is conflicting evidence on whether prior azithromycin (AZM) exposure is associated with reduced susceptibility to AZM (AZMRS) among persons infected with Neisseria gonorrhoeae (NG). METHODS: The study population included Public Health-Seattle and King County Sexual Health Clinic (SHC) patients with culture-positive NG infection at ≥1 anatomic site whose isolates were tested for AZM susceptibility in 2012-2019. We used multivariate logistic regression to examine the association of time since last AZM prescription from the SHC in ≤12 months with subsequent diagnosis with AZMRS NG (minimum inhibitory concentration [MIC], ≥2.0 µg/mL) and used linear regression to assess the association between the number of AZM prescriptions in ≤12 months and AZM MIC level, controlling for demographic, behavioral, and clinical characteristics. RESULTS: A total of 2155 unique patients had 2828 incident NG infections, 156 (6%) of which were caused by AZMRS NG. AZMRS NG was strongly associated with receipt of AZM from the SHC in the prior 29 days (adjusted odds ratio, 6.76; 95% confidence interval [CI], 1.76 to 25.90) but not with receipt of AZM in the prior 30-365 days. Log AZM MIC level was not associated with the number of AZM prescriptions within ≤12 months (adjusted correlation, 0.0004; 95% CI, -.04 to .037) but was associated with number of prescriptions within <30 days (adjusted coefficient, 0.56; 95% CI, .13 to .98). CONCLUSIONS: Recent individual-level AZM treatment is associated with subsequent AZMRS gonococcal infections. The long half-life and persistence of subtherapeutic levels of AZM may result in selection of resistant NG strains in persons with recent AZM use.

Pharyngeal Gonorrhea in Heterosexual Male and Female Sex Partners of Persons With Gonorrhea.

BACKGROUND: Current guidance from the US Centers for Disease Control and Prevention recommends empiric treatment for persons exposed to sexually transmitted infections, including Neisseria gonorrhoeae ( NG ). As an antimicrobial stewardship measure, some clinics now recommend a test and treat strategy, but reliance on urogenital testing only may miss cases. METHODS: We conducted a descriptive analysis of pharyngeal NG infection in men who have sex with women (MSW) and women seeking care at a sexual health clinic in Seattle, WA, from February 2017 to July 2021 because of sexual contact to a partner diagnosed with gonorrhea. We also explored behavioral factors associated with pharyngeal NG positivity (by culture or nucleic acid amplification test by χ2 analysis. RESULTS: Among 352 NG contacts tested for urogenital or pharyngeal infection, 34% were positive for NG at ≥1 anatomic site (27% for MSW and 40% for women). Among 161 NG contacts tested at the pharynx, 30% (n = 48) were positive: 20% of 54 MSW (n = 11) and 35% (n = 37) of 107 women. If only urogenital testing were performed, 36% of MSW NG infections (n = 5) and 19% of female NG infections (n = 9) would have remained unidentified. CONCLUSIONS: Pharyngeal NG is relatively common among MSW and women who have been exposed to NG, and likely represents an underdiagnosed reservoir of NG infection. If empiric treatment is abandoned in favor of testing and treating, testing the throats of heterosexuals will be necessary.

Previous Sexually Transmitted Infections and Partner Services Interviews as Predictors of Subsequent Interview Completion Among Cisgender MSM: Partner Services Fatigue?

BACKGROUND: Anecdotal reports suggest that partner services (PS) are less successful among people with repeat sexually transmitted infection (STI) diagnoses and/or previous PS interactions. We examine whether having repeated STI diagnoses and/or PS interactions is associated with PS outcomes among men who have sex with men (MSM). METHODS: With STI surveillance and PS data for MSM diagnosed with gonorrhea, chlamydia, and/or syphilis from 2007 to 2018, in King County, WA, we used Poisson regression models to examine the relationships between PS outcomes (e.g., completing a PS interview and providing identifying information for a contact) with (1) number of previous STI case episodes and (2) number of previous PS interviews completed. RESULTS: Of the 18,501 MSM STI case patients initiated for interview in the analytic period (2011-2018), 13,232 (72%) completed a PS interview, and 8,030 (43%) had at least 1 prior PS interview. The proportion of initiated cases successfully interviewed declined from 71% among those with no previous PS interview to 66% among those with ≥3 prior interviews. Similarly, the proportion of interviews with ≥1 partner identified declined with greater numbers of previous PS interviews (from 46% [0 interviews] to 35% [≥3 interviews]). In multivariate models, having ≥1 prior PS interview was negatively associated with completing a subsequent interview and providing partner locating information. CONCLUSIONS: Having a history of STI PS interviews is associated with less PS engagement among MSM. New approaches to PS should be explored to address the growing epidemic of STIs among MSM.

Trends in Patient's Use of Sexual Health Services During COVID-19 in a Network of STD Clinics, STD Surveillance Network, 2019 to 2021.

BACKGROUND: The initial years of the COVID-19 pandemic disrupted sexual health care clinic's services. We describe use patterns by patient characteristics, and the use of telehealth (TH) services among a network of sexually transmitted disease (STD) clinics. METHODS: Data were collected using a survey to assess the impact of COVID-19 from March to December 2020 among 7 jurisdictions who contribute STD visit-level data as part of the STD Surveillance Network. As a complement to the survey, retrospective data from January 2019 to December 2021 from these 7 STD clinics in the same 7 jurisdictions were examined for monthly utilization trends by overall visits, patient characteristics, and TH visits. RESULTS: Survey results indicated 7 clinics prioritized patients for in-person visits and 4 jurisdictions reported urgent care centers were the most common referral location. In April 2020 (relative to April 2019) clinic visits and unique patients decreased by 68.0% and 75.8%, respectively. Telehealth were documented in 4 clinics, beginning in March 2020, peaking in December 2020, and tapering until December 2021. We observed the number of clinic visits (-12.2%) and unique patients presenting for care (-27.2%) in December 2021 had yet to return to levels to that seen in December 2019. CONCLUSIONS: Sexually transmitted disease clinics showed fragility and resiliency in their adjustment to the pandemic; allowing for the continuation of services. Overall patient census has been slow to return to prepandemic levels, and many patients may still not be seeking timely care. This could result in missed opportunities to screen and treat STIs and increasing the possibility of harmful sequelae.

Etiologies of Proctitis at a Sexual Health Clinic in Seattle, Washington From 2011 to 2021.

ABSTRACT: We analyzed microbiologic etiologies of proctitis among patients seen in an urban sexual health clinic during 2011 to 2021. Among 759 cases, 179 (24%) tested positive for Neisseria gonorrhoeae , 171 (23%) for Chlamydia trachomatis , 21 (3%) for herpes simplex virus, 30 (4%) for syphilis, and 73 (10%) for multiple pathogens; no pathogen was identified in 425 (56%).

Decreases in Reported Sexually Transmitted Infections During the Time of COVID-19 in King County, WA: Decreased Transmission or Screening?

BACKGROUND: In response to the COVID-19 pandemic, Washington State's Stay Home, Stay Healthy (SHSH) order was implemented on March 24, 2020. We hypothesized that pandemic mitigation measures might reduce sexually transmitted infection (STI) screening and/or transmission. METHODS: We used King County, WA STI surveillance and sexual health clinic (SHC) data from January 1, 2019, to July 31, 2020. We calculated mean weekly case counts for gonorrhea, primary and secondary (P&S) syphilis, male urethral gonorrhea, and early latent (EL) syphilis for 3 periods in 2020: pre-SHSH (January 1-March 23), SHSH (March 24-June 5), and reopening (June 6-July 31). Primary and secondary syphilis and male urethral gonorrhea were used as proxies for sexual behavior, and EL syphilis was used as a proxy for STI screening. We compared SHC visits (2019 vs. 2020) and SHC gonorrhea treatment practices (across 2020 periods). RESULTS: Compared with January to July 2019, from January to July 2020, reported cases of gonorrhea, male urethral gonorrhea, P&S syphilis, and EL syphilis decreased by 9%, 5%, 16%, and 22%, respectively. Mean weekly case counts of gonorrhea, male urethral gonorrhea, and EL syphilis decreased pre-SHSH to SHSH, but all returned to pre-SHSH levels during reopening. Sexual health clinic visits during SHSH were 55% lower in 2020 than in 2019. In the SHC during SHSH, ceftriaxone treatment of gonorrhea decreased, whereas cefixime/cefpodoxime treatment and gonorrhea treatment with no testing increased. CONCLUSIONS: Decreases in reported STIs concurrent with COVID-19 SHSH may reflect a true decline in STI transmission. However, the larger decreases in asymptomatic infections indicate that much of the observed decrease was likely due to decreased screening.

Epidemiologic Treatment for Contacts to Neisseria gonorrhoeae and Chlamydia trachomatis Infection in Sexually Transmitted Disease Clinic Patients in Seattle, WA; 1994 to 2018.

INTRODUCTION: Current Centers for Disease Control and Prevention guidelines recommend that clinicians empirically treat the sex partners of persons with Neisseria gonorrhoeae (GC) or Chlamydia trachomatis (CT) infection before confirming that they are infected. It is possible that this practice, known as epidemiologic treatment, results in overtreatment for uninfected persons and may contribute to development of antimicrobial resistance. We sought to quantify the number of patients who received epidemiologic treatment and the proportion of those who were overtreated. METHODS: We reviewed records from a municipal sexually transmitted disease clinic in Seattle, WA, from 1994 to 2018 to identify visits by asymptomatic patients seeking care because of sexual contact to a partner with GC and/or CT. We defined overtreatment as receipt of antibiotic(s) in the absence of a positive GC/CT test result and calculated the proportions of contacts epidemiologically treated and tested positive for GC/CT and overtreated in five 5-year periods stratified by sex and gender of sex partner. We used the Cochran-Armitage test to assess for temporal trends. RESULTS: The number of asymptomatic contacts epidemiologically treated for GC/CT increased from 949 to 3159 between the 1994-1998 and 2014-2018 periods. In 2014-2018, 55% of persons were overtreated, most (82.1%) of these were men who have sex with men (MSM). The proportion of MSM overtreated decreased from 74% to 65% (P < 0.01), but the total number of overtreated MSM increased from 172 to 1428. DISCUSSION: A high proportion of persons receiving epidemiologic treatment of GC/CT are uninfected. The current practice of routinely treating all sex partners of persons with GC/CT merits reconsideration in light of growing antimicrobial resistance.

The Syphilis Epidemic Among Heterosexuals Is Accelerating: Evidence From King County, Washington.

Background: We characterized the rapid increase in syphilis among cisgender women in King County, Washington, and compared it with trends among cisgender men who have sex with men. Method: We used surveillance data from King County, 2007 to 2022, to describe incidence trends stratified by syphilis stage, gender, and gender of sex partners; trends in pregnant cases and congenital syphilis; and trends in rapid plasma reagin titer at diagnosis among late/unknown duration cases. We used joinpoint regression to analyze trends. Results: Among cisgender women, all-stage syphilis incidence remained stable from 2007 to 2010 but then increased by 16.3% per year (95% CI, 12.0%-20.7%) from 2010 to 2020 and 90.1% per year (95% CI, 26.4%-185.9%) from 2020 to 2022. Early syphilis rates rose gradually from 2007 to 2017 (18% per year; 95% CI, 7.4%-29.6%) and then rapidly from 2017 to 2022 (62.5% per year; 95% CI, 24.1%-112.9%). In contrast, the increase in late/unknown duration syphilis incidence was delayed. Among cisgender men who have sex with women, all-stage syphilis remained stable from 2007 to 2014 and increased 25.0% per year (95% CI, 14.0%-37.0%) from 2014 to 2022. Syphilis incidence increased steadily among men who have sex with men, with all-stage incidence increasing 7.0% per year (95% CI, 4.8%-9.2%) from 2007 to 2022. Median rapid plasma reagin titer among late/unknown duration cases increased significantly over the analysis period. Conclusions: An explosive epidemic of syphilis is ongoing in King County. The delayed increase in asymptomatic late/unknown duration cases relative to early symptomatic cases suggests that there is a large and growing reservoir of recently acquired undiagnosed syphilis in women. New clinical and public health activities are urgently needed to control the growing epidemic.

Effectiveness of the Modified Vaccinia Ankara Vaccine Against Mpox in Men Who Have Sex With Men: A Retrospective Cohort Analysis, Seattle, Washington.

Background: Data on modified Vaccinia Ankara (MVA) vaccine effectiveness against mpox in real-world settings are limited. Methods: We performed a retrospective cohort analysis using Cox proportional hazards regression to estimate the association between vaccination and laboratory-confirmed mpox incidence. Study subjects included all men who have sex with men seen in a sexual health clinic in Seattle, Washington, between 1 January 2020 and 31 December 2022. Subjects' receipt of vaccine and diagnosis with mpox were ascertained from public health vaccine registry and surveillance data. Analyses were adjusted for demographic factors, human immunodeficiency virus (HIV) status, and sexual risk behaviors. Results: The incidence of mpox per 100 person-years was 8.83 among patients with 0 doses, 3.32 among patients with 1 dose, and 0.78 among patients with 2 doses of MVA vaccine. Mpox diagnosis was significantly associated with age category 30-39 and 40-51 years, HIV positivity, syphilis diagnosis in the prior year, >10 sex partners in the last year, and having a clinic visit in the last year. In the multivariate model adjusting for these factors, vaccine effectiveness was 81% for 1 dose and 83% for 2 doses. Conclusions: These data support the effectiveness of the MVA vaccine-including a single dose of the vaccine-in preventing mpox disease and highlight the appropriateness of risk factor-based prioritization of immunization early in the epidemic. The durability of MVA vaccine-induced immunity is unknown, and at-risk persons should receive 2 doses of MVA.

A Demedicalized Model to Provide PrEP in a Sexual Health Clinic.

BACKGROUND: Sexual health clinics (SHCs) serve large numbers of patients who might benefit from preexposure prophylaxis (PrEP). Integrating longitudinal PrEP care into SHCs can overburden clinics. We implemented an SHC PrEP program that task shifted most PrEP operations to nonmedical staff, disease intervention specialists (DIS). METHODS: We conducted a retrospective cohort analysis of PrEP patients in an SHC in Seattle, WA, from 2014 to 2020 to assess the number of patients served and factors associated with PrEP discontinuation. Clinicians provide same-day PrEP prescriptions, whereas DIS coordinate the program, act as navigators, and provide most follow-up care. RESULTS: Between 2014 and 2019, 1387 patients attended an initial PrEP visit, 93% of whom were men who have sex with men. The number of patients initiating PrEP per quarter year increased from 20 to 81. The number of PrEP starts doubled when the clinic shifted from PrEP initiation at scheduled visits to initiation integrated into routine walk-in visits. The percentage of visits performed by DIS increased from 3% in 2014 to 45% in 2019. Median duration on PrEP use was 11 months. PrEP discontinuation was associated with non-Hispanic black race/ethnicity [hazard ratio (HR) 1.34, 95% confidence interval (CI) 1.02 to 1.76], age <20 years (HR 2.17, 95% CI: 1.26 to 3.75), age between 20 and 29 years (HR 1.55, 95% CI: 1.06 to 2.28), and methamphetamine use (HR 1.98, 95% CI: 1.57 to 2.49). The clinic had 750 patients on PrEP in the final quarter of 2019. CONCLUSIONS: A demedicalized SHC PrEP model that task shifts most operations to DIS can provide PrEP at scale to high priority populations.

Changing Patterns of Sexual Behavior and HIV/STI Among Men Who Have Sex With Men in Seattle, 2002 to 2018.

BACKGROUND: The extent to which uptake of biomedical HIV prevention strategies have affected population-level sexual behavior and sexually transmitted infections (STIs) among men who have sex with men (MSM) is not well understood. METHODS: We collected data as part of routine care from MSM attending the municipal STI clinic in Seattle, Washington, 2002-2018. MSM were asked about condom use in the previous 12 months. We classified behaviors into 4 mutually exclusive categories: no anal sex; consistent condom use for anal sex; serosorting [condomless anal sex (CAS) only with HIV-concordant partners]; and CAS with serodiscordant/unknown-status partners. STI/HIV testing was performed per routine clinic protocol. RESULTS: There were 45,656 and 6987 visits by MSM without HIV and MSM with HIV, respectively. The use of antiretroviral therapy and preexposure prophylaxis increased substantially during the study period to 94% and 50%, respectively, by 2018. CAS with serodiscordant/unknown-status partners decreased through 2013 but increased thereafter (to 40% among MSM without HIV; 68% among MSM with HIV). Serosorting increased among MSM without HIV but declined after 2013 among MSM with HIV. Consistent condom use declined for all MSM (from 35% to 11% among MSM without HIV; from 20% to 5% among MSM with HIV). HIV test positivity declined substantially (3.5%-0.5%), whereas STI test positivity increased over time. CONCLUSIONS: Since 2013, CAS with HIV-discordant/unknown-status partners increased substantially concurrent with declining HIV test positivity and increasing STI test positivity. This highlights the success of biomedical HIV prevention strategies to reduce HIV incidence while affirming the need for new approaches to STI prevention.

Low HIV incidence among women following sexually transmitted infection does not support national pre-exposure prophylaxis recommendations.

: Current United States guidelines recommend that clinicians offer HIV pre-exposure prophylaxis (PrEP) to women with gonorrhea or syphilis. We estimated HIV incidence among women following a syphilis, gonorrhea, or chlamydia diagnosis among women in King County, WA using surveillance data from 2008 to 2018. Among women with diagnosed with gonorrhea and among women diagnosed with chlamydia the estimated HIV incidence rates were 0.06 and 0.02 per 100 person years, respectively. No women reported with syphilis were diagnosed with HIV.

The road to tuberculosis (Mycobacterium tuberculosis) elimination in Arkansas; a re-examination of risk groups.

OBJECTIVES: This study was conducted to generate knowledge useful for developing public health interventions for more effective tuberculosis control in Arkansas. METHODS: The study population included 429 culture-confirmed reported cases (January 1, 2004-December 31, 2010). Mycobacterium tuberculosis genotyping data were used to identify cases likely due to recent transmission (clustered) versus reactivation (non-clustered). Poisson regression models estimated average decline rate in incidence over time and assessed the significance of differences between subpopulations. A multinomial logistic model examined differences between clustered and non-clustered incidence. RESULTS: A significant average annual percent decline was found for the overall incidence of culture-confirmed (9%; 95% CI: 5.5%, 16.9%), clustered (6%; 95% CI: 0.5%, 11.6%), and non-clustered tuberculosis cases (12%; 95% CI: 7.6%, 15.9%). However, declines varied among demographic groups. Significant declines in clustered incidence were only observed in males, non-Hispanic blacks, 65 years and older, and the rural population. CONCLUSIONS: These findings suggest that the Arkansas tuberculosis control program must target both traditional and non-traditional risk groups for successful tuberculosis elimination. The present study also demonstrates that a thorough analysis of TB trends in different population subgroups of a given geographic region or state can lead to the identification of non-traditional risk factors for TB transmission. Similar studies in other low incidence populations would provide beneficial data for how to control and eventually eliminate TB in the U.S.