Syphilis has continued to increase over the last several years in the United States, and there is a high degree of coinfection with human immunodeficiency virus (HIV) among infectious syphilis cases, primarily among men who have sex with men (MSM).1–4 Most new HIV infections in the United States occur among gay and bisexual men.5 Some have hypothesized that the increase in cases and coinfections may be due to the rise in social media apps for finding sex partners, social inequality, stigma, increase in condomless sex, deterioration of public health infrastructure, and lack of access to health care. Syphilis is a known risk factor for HIV acquisition, and disease transmission is syndemic.
The federal initiative, Ending the HIV Epidemic (EHE), seeks to reduce transmission of HIV in the United States through a 4-strategy plan, initially targeting efforts among the 48 counties contributing to more than 50% of all new HIV diagnoses.6 This initiative utilizes 4 “pillars”: diagnose all those at risk of HIV infection; treat all those infected to achieve viral suppression; prevent new HIV infection among those at risk; and respond to potential outbreak situations. The EHE stresses implementation of evidence-based interventions (EBI), especially preexposure prophylaxis (PrEP) and linking those with HIV infection to medical care to achieve an undetectable viral load.
Indiana's sexually transmitted disease (STD) district 5 consists of 8 counties including the city of Indianapolis in Marion County. Marion County is 1 of the 48 counties prioritized in the EHE plan. In 2018, Marion County ranked 55th of selected US counties for infectious syphilis with 141 cases reported (14.8 per 100,000 population).2 The Marion County Public Health Department’s (MCPHD) Bell Flower Clinic is the largest STD clinic in Indiana and the only full-service specialty clinic in the district offering diagnostic and treatment services for STDs as well as diagnostic and linkage to care services for HIV.
In the United States, in 2016, among persons living with HIV/acquired immune deficiency syndrome (AIDS) (PLWHA), 49% were retained in care and 53% were virally suppressed.7 Within Indiana, the majority of PLWHA are living in Marion County. Among Marion County HIV diagnoses between 2016 and 2018, 16% (103/630) of new HIV infections were identified by Bell Flower Clinic.8
Even though national guidelines recommend that sexually active persons with HIV infection receive STD testing annually, this is only completed 55% of the time.9 It is estimated that approximately 154,000 persons with HIV in the United States are unaware of their status.10 This study builds on what is already known about HIV outcomes among partners exposed to syphilis to describe the exclusive contribution of partner services (PS) for syphilis in achieving EHE objectives. Outcomes of interest are those identified as being EBIs for HIV prevention including knowledge of HIV status; STD treatment; PrEP; and suppressed or undetectable viral load.
We analyzed early syphilis (ES) cases, less than 1 year’s duration, between 2016 and 2018 reported to Indiana's STD district 5. Data were derived from the Statewide Investigating Monitoring and Surveillance System (SWIMSS). This database contains all reportable STDs throughout the state as well as viral load and CD4 count laboratory results for PLWHA. Data were extracted to relational tables for analysis. Case patients who named partners were connected to partner data by linking the unique ID of the ES case with the unique ID of the partner in the relational tables.
Early syphilis cases who were not interviewed, or did not mention partners, were removed from further analysis. The HIV-positive case patients were separately examined for the same criteria for partners described below.
Disposition codes are a standardized method used by STD Programs to show the outcome of the interaction between public health and the patient or partner (for example, unable to locate, or infected, brought to treatment). Using disposition codes, we calculated the date difference between staging of the syphilis case and completion of PS work for the partner, with an inclusion period of up to 60 days after the case patient's syphilis diagnosis. In this way, we avoided the problem of partners testing positive for HIV before notification of syphilis exposure being counted in the analysis. Dispositions were also examined to identify the number of partners tested for HIV and those receiving syphilis treatment.
Disposition codes are recorded on “field record” forms in SWIMSS, but a field record would not be created for HIV if the ES case patient is HIV-negative. Similarly, partners notified of exposure who chose to test for HIV with their own provider might not have been recorded in SWIMSS. To correctly capture all outcomes, other data sources had to be used for HIV status of partners, including Insight, Marion County Public Health Department’s medical record database, and Indiana's enhanced HIV/AIDS Reporting System. Insight contains all HIV testing conducted by Bell Flower Clinic. Enhanced HIV/AIDS Reporting System contains all statewide HIV case reports.
Characteristics of ES cases were stratified by sexual orientation and demographics. Characteristics of the ES partners were stratified by HIV status. The newly HIV-diagnosed ES partners were examined to count those retained in medical care as of August 2019, and assess viral suppression.
EBI for HIV Prevention
We focused on 4 interventions found to have HIV prevention benefit, namely: learning one’s HIV status; STD treatment; PrEP; and retention in medical care/viral suppression.
Knowledge of one’s HIV status—prevention benefit is gained because some may use knowledge of their own and their partner’s status as a risk reduction method.11 Learning one's status is positive allows a person to access care and treatment. The US Advisory Committee for HIV and STD Prevention asserts that “screening for HIV infection among persons with other STDs is an important HIV prevention strategy.”
The STD treatment is HIV prevention—synergy between STDs and HIV acquisition has long been accepted. Early detection and treatment of other STDs is an effective strategy for preventing sexually transmitted HIV infection.12
PrEP—PrEP has been shown to be effective at reducing HIV acquisition.13
Retention in care/viral suppression—HIV-infected persons with undetectable viral loads are considered unable to transmit the virus.14
Description of PS
Partner services is an evidence-based strategy for identification of new cases of STD and HIV. The HIV case finding is increased when HIV testing is integrated with syphilis PS.15,16 Syphilis PS gives an opportunity to identify those at high risk of testing HIV-positive.17 Local health department STD Programs use Disease Intervention Specialist (DIS) to offer PS for STD and HIV. DIS have been instrumental in providing services to some STD case patients and their exposed partners since the 1940s. DIS are public health workers specially trained to intervene in syphilis transmission. Activities typically performed are: ensuring the case patient is treated (STD) or linked to care (HIV); encouraging the acceptance of PS; and confidential notification of exposed partners to provide testing and treatment as indicated. Referrals for PrEP were added to DIS core activities several years ago.18,19 Confidential notification can be attempted by phone, in person, or the Internet. When the DIS undertakes notification of exposed partners (aka provider referral), studies have shown that this is the most cost-effective method from an individual and societal perspective.20 Syphilis PS is an important method of case finding for both syphilis and HIV.21 Partner services is recognized as cost-effective and is recommended by CDC and the Community Preventive Services Task Force.22,23
A total of 984 ES cases were identified in district 5 between 2016 and 2018, 96% (n = 941) of whom were interviewed for their infection (Table 1). Of the 984 cases, 974 (90%) received adequate syphilis treatment. Most (623 or 64%) were treated by the diagnosing provider and 351 (36%) were treated as a result of DIS intervention. Among ES cases interviewed, 34% of case patients with HIV identified partners needing notification (156 of 461) while 50% of case patients without HIV named partners for notification (222 of 446).
A total of 378 unique individuals named partners, representing 405 ES cases due to 27 repeat infections in the study period. Each case patient group named 2 partners for notification. The HIV-positive case group had a higher number of reinfections than the HIV-negative case group at 12% versus 3.6%, respectively. There were 725 unique individuals named as exposed partners and 761 exposures among these individuals during the study period, taking into account individuals named more than once.
There was a larger proportion of MSM (97%) in the HIV-positive case group for whom partners were elicited than the HIV-negative case group (67%). There were no women in the HIV-positive ES case group and 77 in the HIV-negative case group. Among the HIV-negative ES case patients, white race accounted for 53% and black race 38%. Among the HIV-positive ES case patients, this was reversed with 35% of cases white and 58% black. Similarly, the most common age group for both was 25 to 29 years but the next highest age group for the HIV-negative cases was 20 to 24 years, whereas it was 30 to 34 years for the HIV-positive cases.
A total of 414 individual partners (423 exposures) were named by the HIV-negative ES cases and 156 individual partners (174 exposures) were named by the HIV-positive ES case patients (Table 2). Among the partners to HIV-negative syphilis case patients, 16% (n = 68) were found to be previously HIV-positive and 21% (n = 86) had an unknown HIV status. Sixty-three percent (n = 260) were tested for HIV at time of syphilis exposure notification, with 251 (96.5%) testing negative and 9 (3.5%) testing newly HIV-positive. Examination of HIV care status of the 9 new diagnoses found that 78% (n = 7) were retained in care as of August 2019, and 57% (4/7) of those in care had an undetectable viral load (less than 50 copies of HIV per milliliter of blood).
Among the partners to HIV-positive syphilis case patients 50% (n = 154) were found to be previously HIV-positive and 21% (n = 65) had an unknown HIV status. Thirty percent (n = 92) were tested for HIV at notification, with 79 (86%) testing negative and 13 (14%) newly HIV-positive. Examination of HIV care status (not shown in table) of the 13 new diagnoses found that 62% (n = 8) were retained in care as of August 2019; 50% (4/8) of those in care had an undetectable viral load and 1 (13%) was virally suppressed.
Among both ES case groups the greatest proportion of all partners named were in the 25–29 year old age group. Among new HIV-positive diagnoses, MSM comprised 89% from the HIV–negative ES case group and 100% from the HIV-positive ES case group.
Race differed by HIV status among the ES cases with black race representing the majority of cases (58%) and partners (53%) for the HIV-positive cases. White race was predominant for the HIV-negative ES cases (53%) and partners (48%). There were no appreciable differences in ethnicity between the 2 groups, with approximately 10% of ES cases and less than 10% of partners of Hispanic ethnicity.
Of the 761 exposures, approximately two thirds (n = 501) were dispositioned within 21 days. No differences in timeliness were noted between partners named by an HIV-positive or HIV-negative case patient.
Among partners with a syphilis exposure disposition, a total of 400 were treated for syphilis, 63 of whom were new syphilis diagnoses; 291 were preventively treated; and 46 were treated for syphilis before the notification (Table 3).
Referrals for PrEP were not recorded in SWIMSS. Bell Flower Clinic refers people to Eskenazi Hospital for PrEP, and they were able to provide us with the number of PrEP referrals received by Bell Flower during all but 2 months of the study period (March 2016 to December 2018), but not the number of successful enrollments in PrEP. In this period, Bell Flower made 168 referrals for PrEP (personal communication, Thomas Kleyn, Clinical Pharmacy Specialist, Eskenazi Health, 3/27/20). The number of partners learning their HIV status was 352: 260 from the HIV-negative case patient group and 92 from the HIV-positive case patient group.
Aligning Findings With EBIs
Knowledge of HIV status—the number of partners learning their HIV status was 352, 260 from the HIV-negative case patient group and 92 from the HIV-positive case patient group. One new HIV case was identified for every 43 ES patients interviewed.
STD treatment for HIV prevention—among partners with a syphilis exposure disposition, a total of 400 were treated for syphilis, 63 of whom were new syphilis diagnoses; 291 were preventively treated; and 46 were treated for syphilis before the notification. Among the ES case patients, 351 were treated for syphilis due to DIS intervention.
PrEP—Bell Flower Clinic made 168 PrEP referrals in the study period.
Retention in care/suppressed or undetectable viral load—examination of HIV care status of the 22 new diagnoses found that 68% (n = 15) were retained in care as of August 2019; 60% (9/15) had viral loads that were either undetectable (n = 8) or virally suppressed (n = 1).
It is not possible to definitively say if the partner was named by only 1 case patient nor how often 2 partners were exposed by the same case patient. We believe this effect is minimal on our findings. We examined the record of each partner testing newly HIV-positive, and none were identified with this attribute.
Dispositions used by DIS are not always representative of the true outcome of the interaction24 so there may be some misclassification. Authors attempted to mitigate any errors due to this by record review for accuracy on all partners newly HIV-positive and on those with syphilis dispositions indicating that an HIV test should have been performed.
Findings likely underestimate the actual effect of PS due to low acceptance of PS by DIS, with only 40% of ES interviews resulting in a partner to notify.
There are likely additional benefits from syphilis PS that would support the EHE pillars that were unable to be quantified for this study due to database limitations, such as PrEP enrollment and the number of PLWHA linked or re-linked to care at diagnosis of syphilis exposure.
Nationally, there is variability in the rate of new HIV positivity depending on the testing venue and whether those tested had known exposures to HIV-positive individuals. The CDC recommends HIV testing be conducted using an opt-out approach in which consent is implied in the general consent for medical services.25 For those tested as a result of community HIV testing or opt-out screening programs, positivity ranges from 0.15% to 1%.26–28 A large hospital emergency department in Marion County reports that in 2018 a total of 23 new HIV diagnoses were identified, for positivity of 0.31%, from its opt-out testing program (personal communication, John Nichols, HIV Prevention Program Director, ISDH Division of HIV/STD/Viral Hepatitis, 8/21/19).
For those tested due to an exposure to an HIV-positive person, the new diagnosis positivity can be as high as 38%.29–31 Some studies reported on new HIV positivity among syphilis case patients, yielding overall HIV positivity as high as 6%.32 When partner positivity is examined by the HIV status of the syphilis case naming the partner, variable rates were identified, with much higher HIV positivity rates achieved if the syphilis case patient had previously-diagnosed HIV.
In this analysis, the new HIV case rate yield of 3.5% among tested partners to the HIV-negative syphilis case patients is noteworthy because these partners did not have an identified HIV exposure at time of syphilis notification. Our findings indicate that 1 new HIV diagnosis was identified for every 43 ES interviews conducted, consistent with another study.33 Among all Bell Flower HIV diagnoses, 21.3% (22 of 103) during the study period are attributable to syphilis PS. These findings provide further support that the intervention of syphilis PS is effective at HIV case finding.
EHE pillar 1: diagnose all people with HIV as early as possible (addresses the EBI of Knowledge of one's HIV status).
Testing for HIV was administered to 352 exposed partners. Twenty-two individuals received a new HIV diagnosis as a result of syphilis PS. One new HIV case was identified for every 43 ES cases interviewed.
EHE pillar 2: treat people with HIV rapidly and effectively to achieve viral suppression (addresses the EBI of retention in care/viral suppression).
In this study, we documented that 68% retained in HIV care with 60% of those in care undetectable or virally suppressed, exceeding the national averages. Syphilis PS was successful in testing partners to syphilis cases quickly, leading to timely identification of HIV status, with two thirds of partner records dispositioned within 21 days of the case patient's diagnosis.
EHE pillar 3: prevent new HIV infections via proven interventions (addresses the EBIs of STD treatment as HIV prevention, and PrEP).
Treatment for syphilis was provided to 400 partners, likely reducing their ability to acquire HIV in the short term if negative, and to transmit HIV in the short term if positive.
Between March 2016 and December 2018, 168 people were referred to PrEP.
Previous studies have demonstrated the effectiveness of PS for STD and HIV prevention, highlighted the rates of new HIV diagnoses among syphilis patients, and examined HIV case finding attributable to PS from HIV cases. Key findings from this study describe HIV outcomes due to syphilis PS even when the case patient is HIV-negative, reinforcing the critical role STD Programs can play in contributing to the EHE pillars.
Case finding resulting from syphilis PS may identify more new HIV cases than a strategy which relies primarily on persons coming forward for community testing. In this analysis, new HIV positivity from partners of ES cases is greater than that seen at voluntary testing sites or through opt-out screening. State and local areas prioritized for EHE may want to ensure that many options exist for testing to include community testing, opt-out screening in venues such as emergency departments, as well as ensuring a robust syphilis PS program.
Given this evidence of syphilis PS contributions to HIV prevention, it is important that adequate resources are allocated and maintained for STD programs and DIS staff, and that STD programs are included in local EHE planning.
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