Expanding Medicaid to Reduce Human Immunodeficiency Virus Transmission in Houston, Texas: Insights From a Modeling Study.

CONTEXT: Medicaid expansion has been nationally shown to improve engagement in the human immunodeficiency virus (HIV) treatment and prevention continua, which are vital steps to stopping the HIV epidemic. New HIV infections in the United States are disproportionately concentrated among young Black men who have sex with men (YBMSM). Houston, TX, is the most populous city in the Southern United States with a racially/ethnically diverse population that is located in 1 of 11 US states that have not yet expanded Medicaid coverage as of 2021. METHODS: An agent-based model that incorporated the sexual networks of YBMSM was used to simulate improved antiretroviral treatment and pre-exposure prophylaxis (PrEP) engagement through Medicaid expansion in Houston, TX. Analyses considered the HIV incidence (number of new infections and as a rate metric) among YBMSM over the next 10 years under Medicaid expansion as the primary outcome. Additional scenarios, involving viral suppression and PrEP uptake above the projected levels achieved under Medicaid expansion, were also simulated. RESULTS: The baseline model projected an HIV incidence rate of 4.96 per 100 person years (py) and about 368 new annual HIV infections in the 10th year. Improved HIV treatment and prevention continua engagement under Medicaid expansion resulted in a 14.9% decline in the number of annual new HIV infections in the 10th year. Increasing viral suppression by an additional 15% and PrEP uptake by 30% resulted in a 44.0% decline in new HIV infections in the 10th year, and a 27.1% decline in cumulative infections across the 10 years of the simulated intervention. FINDINGS: Simulation results indicate that Medicaid expansion has the potential to reduce HIV incidence among YBMSM in Houston. Achieving HIV elimination objectives, however, might require additional effective measures to increase antiretroviral treatment and PrEP uptake beyond the projected improvements under expanded Medicaid.

Integrated molecular and affiliation network analysis: Core-periphery social clustering is associated with HIV transmission patterns.

This study investigates the two-mode core-periphery structures of venue affiliation networks of younger Black men who have sex with men (YBMSM). We examined the association between these structures and HIV phylogenetic clusters, defined as members who share highly similar HIV strains that are regarded as a proxy for sexual affiliation networks. Using data from 114 YBMSM who are living with HIV in two large U.S. cities, we found that HIV phylogenetic clustering patterns were associated with social clustering patterns whose members share affiliation with core venues that overlap with those of YBMSM. Distinct HIV transmission patterns were found in each city, a finding that can help to inform tailored venue-based and network intervention strategies.

Déjà vu? A Comparison of Syphilis Outbreaks in Houston, Texas.

BACKGROUND: After reaching an all-time low in 2000, syphilis incidence in the United States has increased as the burden shifted from heterosexuals to men who have sex with men (MSM). Houston, Texas, experienced 2 outbreaks of syphilis during this transformation in trends. Further evaluation is necessary to determine if these outbreaks occurred among the same subpopulations. METHODS: Surveillance data collected on all reported infectious syphilis cases in Houston from 1971 to 2013 were analyzed. Trends in incidence among MSM and human immunodeficiency virus-positive Houston residents were examined. Peak syphilis years subsequent to 1999, years 2007 and 2012, were compared to determine if outbreaks arose in distinctive subpopulations. Categorical variables between these years were compared using chi-square and Fisher's exact tests, whereas further associations between the years were evaluated using multivariable logistic regression. RESULTS: Incidence among MSM was 20.9 to 32.1 times higher than other men from 2005 to 2013. After adjusting for covariates, cases in 2012 were significantly more likely to be Hispanic (adjusted odds ratio [AOR] = 1.61; 95% confidence interval [95% CI], 1.03-2.53), reported meeting partners via the Internet (AOR, 1.74; 95% CI, 1.18-2.58), and engaged in anonymous sex (AOR, 1.92; 95% CI, 1.40-2.63) in comparison to cases in 2007. CONCLUSIONS: We found marked disparities of syphilis by subpopulation in Houston. Herein, we present evidence that outbreaks have been distinct in a major southern city with a high burden of syphilis.

Factors associated with peridomestic Triatoma sanguisuga (Hemiptera: Reduviidae) presence in southeastern Louisiana.

Although rare, there have been isolated reports of autochthonous transmission of Trypanosoma cruzi Chagas in the United States. In June 2006, a human case of domestically transmitted T. cruzi was identified in southern Louisiana. To examine the localized risk of human T. cruzi infection in the area surrounding the initial human case, environmental surveys of households in the area and a serological survey of the residents were performed between September 2008 and November 2009. Human T. cruzi infection was determined using a rapid antigen field test, followed by confirmatory enzyme-linked immunosorbent assay testing in the laboratory. A perimeter search of each participating residence for Triatoma sanguisuga (LeConte), the predominant local triatomine species, was also performed. No participating individuals were positive for antibodies against T. cruzi; however, high levels of T. cruzi infection (62.4%) were detected in collected T. sanguisuga. Households with T. sanguisuga presence were less likely to use air conditioning, and more likely to have either chickens or cats on the property. While the human risk for T cruzi infection in southeastern Louisiana is low, a high prevalence of infected T. sanguisuga does indicate a substantial latent risk for T. cruzi peridomestic transmission. Further examination of the behavior and ecology of T. sanguisuga in the region will assist in refining local T. cruzi risk associations.

Characteristics and risk of syphilis diagnosis among HIV-infected male cohort: a population-based study in Houston, Texas.

BACKGROUND: This population-based study assessed the characteristics, timing, and risk of syphilis diagnoses among HIV-infected males in Houston, Texas. METHODS: A retrospective cohort of males newly diagnosed as having HIV between January 2000 and December 2002 was constructed using HIV surveillance data. These individuals were cross-referenced to sexually transmitted disease surveillance data to ascertain early syphilis diagnoses for the subsequent 10 years. Multivariable Cox regression was used to identify risk factors for syphilis diagnosis while controlling for the effects of covariates. RESULTS: Approximately 6% of the HIV-infected male cohort received early syphilis diagnoses during a 10-year period. Of these comorbid individuals, 40.8% received an incident syphilis diagnosis 5 years or more after their HIV diagnosis. Men who have sex with men (MSM) transmission risk was associated with significantly increased hazard of having a syphilis diagnosis in multivariable analysis (adjusted hazard ratio [HR] of a syphilis diagnosis, 5.24; 95% confidence interval, 3.41-8.05). Compared with men who were older than 40 years at HIV diagnosis, those 13 to 19 years old were 4.06 (2.18-7.55) times more likely to obtain a syphilis diagnosis. The HRs of having an HIV-syphilis comorbidity decreased as age increased. Compared with whites, non-Hispanic African Americans had 1.59 (1.11-2.26) times increased risk of having a subsequent syphilis diagnosis. Risk-stratified HRs showed that MSM had an increased risk of contracting syphilis in all race/ethnicity and age groups. CONCLUSIONS: This study suggests that HIV-positive African Americans, youth, and MSM had increased risk of having a subsequent syphilis diagnosis. Targeting these groups with STI prevention messaging may be beneficial to reducing comorbidity.

Predictors of HIV Molecular Cluster Membership and Implications for Partner Services.

Public health surveillance data used in HIV molecular cluster analyses lack contextual information that is available from partner services (PS) data. Integrating these data sources in retrospective analyses can enrich understanding of the risk profile of people in clusters. In this study, HIV molecular clusters were identified and matched to information on partners and other information gleaned at the time of diagnosis, including coinfection with syphilis. We aimed to produce a more complete understanding of molecular cluster membership in Houston, Texas, a city ranking ninth nationally in rate of new HIV diagnoses that may benefit from retrospective matched analyses between molecular and PS data to inform future intervention. Data from PS were matched to molecular HIV records of people newly diagnosed from 2012 to 2018. By conducting analyses in HIV-TRACE (TRAnsmission Cluster Engine) using viral genetic sequences, molecular clusters were detected. Multivariable logistic regression models were used to estimate the association between molecular cluster membership and completion of a PS interview, number of named partners, and syphilis coinfection. Using data from 4,035 people who had a viral genetic sequence and matched PS records, molecular cluster membership was not significantly associated with completion of a PS interview. Among those with sequences who completed a PS interview (n = 3,869), 45.3% (n = 1,753) clustered. Molecular cluster membership was significantly associated with naming 1 or 3+ partners compared with not naming any partners [adjusted odds ratio, aOR: 1.27 (95% confidence interval, CI: 1.08-1.50), p = .003 and aOR: 1.38 (95% CI: 1.06-1.81), p = .02]. Alone, coinfection with syphilis was not significantly associated with molecular cluster membership. Syphilis coinfection was associated with molecular cluster membership when coupled with incarceration [aOR: 1.91 (95% CI: 1.08-3.38), p = .03], a risk for treatment interruption. Enhanced intervention among those with similar profiles, such as people coinfected with other risks, may be warranted.

Impact of molecular sequence data completeness on HIV cluster detection and a network science approach to enhance detection.

Detection of viral transmission clusters using molecular epidemiology is critical to the response pillar of the Ending the HIV Epidemic initiative. Here, we studied whether inference with an incomplete dataset would influence the accuracy of the reconstructed molecular transmission network. We analyzed viral sequence data available from ~ 13,000 individuals with diagnosed HIV (2012-2019) from Houston Health Department surveillance data with 53% completeness (n = 6852 individuals with sequences). We extracted random subsamples and compared the resulting reconstructed networks versus the full-size network. Increasing simulated completeness was associated with an increase in the number of detected clusters. We also subsampled based on the network node influence in the transmission of the virus where we measured Expected Force (ExF) for each node in the network. We simulated the removal of nodes with the highest and then lowest ExF from the full dataset and discovered that 4.7% and 60% of priority clusters were detected respectively. These results highlight the non-uniform impact of capturing high influence nodes in identifying transmission clusters. Although increasing sequence reporting completeness is the way to fully detect HIV transmission patterns, reaching high completeness has remained challenging in the real world. Hence, we suggest taking a network science approach to enhance performance of molecular cluster detection, augmented by node influence information.

Methodological synthesis of Bayesian phylodynamics, HIV-TRACE, and GEE: HIV-1 transmission epidemiology in a racially/ethnically diverse Southern U.S. context.

This study introduces an innovative methodological approach to identify potential drivers of structuring HIV-1 transmission clustering patterns between different subpopulations in the culturally and racially/ethnically diverse context of Houston, TX, the largest city in the Southern United States. Using 6332 HIV-1 pol sequences from persons newly diagnosed with HIV during the period 2010-2018, we reconstructed HIV-1 transmission clusters, using the HIV-TRAnsmission Cluster Engine (HIV-TRACE); inferred demographic and risk parameters on HIV-1 transmission dynamics by jointly estimating viral transmission rates across racial/ethnic, age, and transmission risk groups; and modeled the degree of network connectivity by using generalized estimating equations (GEE). Our results indicate that Hispanics/Latinos are most vulnerable to the structure of transmission clusters and serve as a bridge population, acting as recipients of transmissions from Whites (3.0 state changes/year) and from Blacks (2.6 state changes/year) as well as sources of transmissions to Whites (1.8 state changes/year) and to Blacks (1.2 state changes/year). There were high rates of transmission and high network connectivity between younger and older Hispanics/Latinos as well as between younger and older Blacks. Prevention and intervention efforts are needed for transmission clusters that involve younger racial/ethnic minorities, in particular Hispanic/Latino youth, to reduce onward transmission of HIV in Houston.

Human Immunodeficiency Virus in the State of Texas of the United States: Past Reflections, Present Shortcomings, and Future Needs of the Public Health Response.

A strategy titled "Ending the HIV Epidemic: A Plan for America" aims to reduce human immunodeficiency virus (HIV) incidence in the United States by at least 90% by 2030, using diagnosis, treatment, and prevention strategies. Texas is a Southern state that has one of the highest numbers of new HIV diagnoses and people with HIV in the country, and where HIV disproportionately impacts minorities. We retrace the historical epidemic in its largest city, Houston, to illustrate the lessons learned and milestones accomplished, which could serve as guideposts for the future. We examine the current epidemic in Texas, including the achieved levels of HIV testing, treatment continua, and pre-exposure prophylaxis prescription, and compare and contrast these with the national estimates and Plan targets. Our findings call for urgent and accelerated expansion of efforts to end HIV in Texas.

Re-engagement in HIV Care: A Clinical and Public Health Priority.

As many as 40-50% of persons living with HIV (PLWH) who once were in HIV care are no longer in care. It is estimated that these individuals account for over 60% of HIV transmissions. So, preventing the leaving of care and re-engaging PLWH with care are crucial if the HIV epidemic is to be brought under control. Clinicians can improve retention by keeping in close contact with patients. Governmental public health agencies have great expertise in finding and engaging in care persons with sexually transmitted infections. This expertise can be used to re-engage PLWH with HIV care, but it can only be utilized if the agencies know that someone is out of care. Data on who has left care are in the hands of HIV providers. This requires a close working relationship between HIV providers and public health agencies.

Benefits of a routine opt-out HIV testing and linkage to care program for previously diagnosed patients in publicly funded emergency departments in Houston, TX.

BACKGROUND: The Routine Universal Screening for HIV program provides opt-out HIV testing and linkage to care for emergency department (ED) patients in Harris Health System, Houston, TX. Seventy-five percent of patients testing positive in this program have been previously diagnosed. Whether linkage to care is increased among these patients is unknown. METHODS: We conducted a retrospective cohort study of persons tested for HIV in the ED between 2008 and 2012 but had a previously documented positive HIV test ≥1 year prior. Outcomes were engagement in care (≥1 HIV outpatient visits in 6 months), retention in care (≥2 HIV outpatient visits in 12 months, at least 3 months apart), and virologic suppression (<200 copies/mL in 12 months) compared before and after the ED visit. Analysis was conducted using McNemar test and multivariate conditional logistic regression. RESULTS: A total of 202,767 HIV tests identified 2068 previously diagnosed patients. The mean age was 43 years with 65% male and 87% racial and ethnic minorities. Engagement in care increased from 41.3% previsit to 58.8% postvisit (P < 0.001). Retention in care increased from 32.6% previsit to 47.1% postvisit (P < 0.001). Virologic suppression increased from 22.8% previsit to 34.0% postvisit (P < 0.001). Analyses revealed that engagement in care after visit improved most among younger participants (ages 16-24 years), retention improved across all groups, and virologic suppression improved most among participants aged 25-34 years. CONCLUSIONS: Routine opt-out HIV testing in an ED paired with standardized service linkage improves engagement, retention, and virologic suppression in previously diagnosed patients.

HIV testing implementation in two urban cities: practice, policy, and perceived barriers.

BACKGROUND: Although funding has supported the scale up of routine, opt-out HIV testing in the US, variance in implementation mechanisms and barriers in high-burden jurisdictions remains unknown. METHODS: We conducted a survey of health care organizations in Washington, DC and Houston/Harris County to determine number of HIV tests completed in 2011, policy and practices associated with HIV testing, funding mechanisms, and reported barriers to testing in each jurisdiction and to compare results between jurisdictions. RESULTS: In 2012, 43 Houston and 35 DC HIV-testing organizations participated in the survey. Participants represented 85% of Department of Health-supported testers in DC and 90% of Department of Health-supported testers in Houston. The median number of tests per organization was 568 in DC and 1045 in Houston. Approximately 50% of organizations in both DC and Houston exclusively used opt-in consent and most conducted both pre- and post-test counseling with HIV testing (80% of organizations in DC, 70% in Houston). While the most frequent source of funding in DC was the Department of Health, Houston organizations primarily billed the patient or third-party payers. Barriers to testing most often reported were lack of funding, followed by patient discomfort/refusal with more barriers reported in DC. CONCLUSIONS: Given unique policies, resources and programmatic contexts, DC and Houston have taken different approaches to support routine testing. Many organizations in both cities reported opt-in consent approaches and pre-test counseling, suggesting 2006 national HIV testing recommendations are not being followed consistently. Addressing the barriers to testing identified in each jurisdiction may improve expansion of testing.

Assessing HIV testing and linkage to care activities and providing academic support to public health authorities in Houston, TX.

BACKGROUND: Health departments often have little knowledge of HIV testing and linkage activities outside of those they directly fund. Many health departments also have limited access to outside academic expertise. METHODS: We conducted a survey of health organizations in the Houston/Harris County region to determine the number of HIV tests completed in 2011, activities that organizations conducted to promote linkage to care for persons newly diagnosed with HIV, and barriers to linkage to care. We also convened a Scientific Advisory Council to advise the local health department on HIV prevention activities. RESULTS: In 2012, 55 of 84 organizations (65.5%) completed the survey and 43 of those 55 organizations reported conducting HIV testing, so were included in this analysis. Organizations reported conducting 210,565 HIV tests in 2011 and 50.9% under health department contract. The median number of tests per organization was 1045 (interquartile ratio: 159-3520). More than 90% of the organizations used active linkage to care methods, but only 46.5% had written linkage to care protocols. Barriers to linkage to care most often reported were client refusal followed by staff capacity and funding limitations. The Scientific Advisory Council provided valuable informal expertise to the local health department. CONCLUSIONS: Half of the HIV testing in the Houston/Harris County region is conducted without local health department funding, and half the organizations conducting HIV testing have linkage to care protocols. The findings of the study and Scientific Advisory Council advice have helped the health department with policy, procedures, evaluation tools, and technical assistance offerings.